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Optimization of a Pretreatment to Reduce Oil Absorption in Fully Fried, Battered and
Breaded Chicken Using Whey Protein Isolate as a Postbreading Dip
A thesis presented to
the faculty of
the College of Health and Human Services of Ohio University
In partial fulfillment
of the requirements for the degree
Master of Science
Eunice Mah
June 2008
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This thesis titled
Optimization of a Pretreatment to Reduce Oil Absorption in Fully Fried, Battered, and
Breaded Chickens Using Whey Protein Isolate as a Postbreading Dip
by
EUNICE MAH
has been approved for
the School of Human and Consumer Sciences
and the College of Health and Human Services by
Robert G. Brannan
Assistant Professor of Human and Consumer Sciences
Gary S. Neiman
Dean, College of Health and Human Services
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ABSTRACT
MAH, EUNICE, M.S., June 2008, Food and Nutrition
Optimization of a Pretreatment to Reduce Oil Absorption in Fully-Fried, Battered, and
Breaded Chicken Using Whey Protein Isolate as a Postbreading Dip (193 pp.)
Director of Thesis: Robert G. Brannan
As consumers become more aware of the deleterious effects of a high-fat diet,
there are increased efforts to lower fat content in foods. The effectiveness of whey
protein isolate (WPI) solution as a postbreading dip to reduce oil absorption in deep-fried,
battered, and breaded chicken patties and its effect on sensory properties was
investigated. Chicken patties were battered, breaded with either crackermeal or Japanese
breadcrumbs, and dipped in WPI solutions prepared at four different protein
concentrations (0%, 2.5%, 5%, and 10% w/w WPI) that were adjusted to pH 2, 3, and 8
before being deep-fried. Undipped chicken patties served as the control. Overall, the most
effective treatment was observed for WPI solutions made at high concentrations (5% and
10% WPI) at low pH levels (pH 2 and 3). The highest lipid reduction was 31.2% for
patties breaded with crackermeal (CMP) at pH 2 with 5% WPI and 37.5% for patties
breaded with Japanese breadcrumbs (JBP) at pH 2 with 10% WPI. The only perceivable
sensory changes in treated patties were related to color, hardness, and crunchiness.
Increasing WPI concentration caused darkening of JBP but made CMP lighter while
patties treated at pH 8 were significantly darker across all WPI concentrations. The
presence of WPI increased perceived hardness and crunchiness for CMP but only
increased perceived hardness for JBP. Variations in pH levels did not affect texture for
both breading systems. JBP that showed the highest lipid reduction (10% WPI at pH 2)
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were observed to be darker, less yellow, but did not produce any perceivable changes in
hardness or crunchiness, while CMP with the lowest lipid content (5% WPI at pH 2) were
darker, more yellow, harder, and crunchier. These results suggest that WPI exhibits oilbarrier properties that do not significantly affect the flavor of the product, irregardless of
breading type, thus making it a promising alternative in lowering fat content of fried
foods.
Approved: _____________________________________________________________
Robert G. Brannan
Assistant Professor of Human and Consumer Sciences
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ACKNOWLEDGMENTS
I would like to acknowledge the following amazing individuals who have supported me
directly and indirectly throughout my M. S. studies and in the production of this thesis.
Thank you so much for making me the person that I am.
Dr. Robert G. Brannan
Joshua Bear
Dr. Darlene Berryman
Joshua O’Donnel
Dr. Elizabeth Crockett
Julian Price
Dr. Ann Paulins
Katie Horn
Amanda Palmer
Keely Trisel
(Ashley) Beamish
Ken McLean
Ashley Zurmehly
Lisa Dael
Beth Wiseman
Dr. Margaret Manoogian
Bobbi Conliffe
Rachel Bisset
Chris Sandford
Sarah Diamond
Crystal Hazen
Simona Allen
Daria Janssen
Svetha Swaminathan
David Holben
Dr. Sky Cone
Dr. Deb Murray
Vishakha Magon
Ms. Diana Manchester
Doug Grammer
Dr. Fang Meng
All my other friends, classmates, and
professors at Ohio University
Gary Saum
Gerard Akindes (and gang)
The funding agency:
Dr. Grace Brannan
National Dairy Council Discovery Pilot
Program
Grant Harris
Dr. Greg Janson
Jane Boney
Jessica Grey
Jody Grenert
And last but not least,
My mum, dad, brother, and sister who are
always there for me.
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TABLE OF CONTENTS
Page
Abstract ................................................................................................................................3
Acknowledgments................................................................................................................5
List of Tables .....................................................................................................................11
List of Figures ....................................................................................................................13
Chapter 1: Introduction ......................................................................................................14
Statement of the Problem ...................................................................................... 16
Research Questions ............................................................................................... 17
Significance of Study ............................................................................................ 17
Delimitations and Limitations............................................................................... 18
Definition of Terms............................................................................................... 20
List of Abbreviations and Acronyms .................................................................... 21
Chapter 2: Review of the Literature...................................................................................22
Introduction ........................................................................................................... 22
Consumption of Fried Foods and Fat Intake............................................. 22
Battered and Breaded Foods ..................................................................... 24
Theories of Oil Uptake in Fried Items .................................................................. 26
Stages of Deep-Fat Frying ........................................................................ 26
Mechanisms of Oil Absorption ................................................................. 27
Water Replacement ....................................................................... 27
Cooling-Phase Effect .................................................................... 27
Surfactant Theory of Oil Absorption ............................................ 31
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Factors Affecting Oil Absorption ......................................................................... 32
External Factors Affecting Oil Absorption ............................................... 33
Composition of the Frying Oil ...................................................... 33
Frying Time and Temperature ...................................................... 33
Postfry Handling ........................................................................... 34
Intrinsic Factors Affecting Oil Absorption ............................................... 34
Methods for Reduction of Oil Absorption ............................................................ 35
Nonprotein-Based Coatings or Films........................................................ 37
Protein-Based Coatings or Films .............................................................. 42
Protein Gelation ............................................................................ 45
Factors affecting protein gelation ..................................... 45
Whey Protein ................................................................................ 48
Gelation of Whey Protein ............................................................. 49
Effect of pH on whey protein gelation and oil uptake. ..... 51
Effect of concentration on whey protein gelation and oil
uptake.. .............................................................................. 53
Sensory Evaluation of Foods ................................................................................ 55
Conclusion ............................................................................................................ 57
Chapter 3: Methodology ....................................................................................................60
Overview of Approach .......................................................................................... 60
Data Collection and Analysis................................................................................ 64
Materials ................................................................................................... 64
Preparation of Deep Fried Samples .......................................................... 64
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Objective Analysis ........................................................................ 65
Oil degradation.................................................................. 65
Lipid analysis. ................................................................... 65
Moisture analysis. ............................................................. 66
Texture and color analysis. ............................................... 66
Sensory Analysis........................................................................... 68
Panelist selection and training. ......................................... 68
Evaluation of samples. ...................................................... 70
Statistical Analysis ........................................................................ 70
Chapter 4: Results ..............................................................................................................72
Oil Degradation ..................................................................................................... 72
Coating Pickup ...................................................................................................... 73
Lipid and Moisture Content .................................................................................. 75
Surface Appearance .............................................................................................. 85
Texture .................................................................................................................. 89
Mouth Feel Sensation and Flavor ......................................................................... 94
Chapter 5: Discussion and conclusion ...............................................................................98
Oil Degradation ..................................................................................................... 98
Effect of WPI Treatment on Lipid Content .......................................................... 98
Effect of WPI Treatment on Moisture Content................................................... 101
Effect of WPI Treatment on Organoleptic Properties of Fried Chicken Patties . 102
Surface Appearance: Color ..................................................................... 102
Texture: Hardness and Crunchiness........................................................ 105
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Mouth Feel Sensation and Flavor ........................................................... 107
Conclusion .......................................................................................................... 108
Future Studies ..................................................................................................... 109
References ........................................................................................................................111
Appendix A: IRB Form ...................................................................................................132
Appendix B: Timeline for Sensory Selection, Training, and Sampling ..........................146
Appendix C: Sensory Panel Questionnaire ......................................................................149
Appendix D: Consent Form .............................................................................................151
Appendix E: Training Session 1 ......................................................................................153
Appendix F: Training Session 2 ......................................................................................156
Appendix G: Training Session 3 ......................................................................................158
Appendix H: Standard Intensity Hardness Scale .............................................................160
Appendix I: Standard Intensity Crispness Scale ..............................................................161
Appendix J: Standard Intensity Juiciness Scale ...............................................................162
Appendix K: Training Session 4 ......................................................................................163
Appendix L: Training Session 5 ......................................................................................165
Appendix M: Training Session 6 .....................................................................................167
Appendix N: Training Session 7 ......................................................................................169
Appendix O: Training Session 8 ......................................................................................172
Appendix P: Training Session 9 ......................................................................................174
Appendix Q: Training Session 10 ....................................................................................176
Appendix R: Training Session 11 ....................................................................................180
Appendix S: Training Session 12 ....................................................................................182
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Appendix T: Sensory Attributes for Cooked Ground Chicken ........................................184
Appendix U: Ballot for Cooked Ground Chicken ...........................................................185
Appendix V: Sensory Attributes for Fried, Battered, and Breaded Chicken Patties .......186
Appendix W: Ballot for Crackermeal-Coated Patties ......................................................188
Appendix X: Ballot for Japanese Breadcrumb-Coated Patties ........................................190
Appendix Y: Sampling Code and Order for Crackermeal-Coated Patties ......................192
Appendix Z: Sampling Code and Order for Japanese Breadcrumb-Coated Patties ........193
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LIST OF TABLES
Page
Table 1: Examples of Nonprotein Ingredients Used in Formulations for Reduction of
Oil Absorption in Fried Foods ...........................................................................................41
Table 2: Examples of Protein Ingredients Used in Formulations in Reduction of Oil
Absorption in Fried Foods .................................................................................................44
Table 3: Effects of pH Level Variations on Whey Protein Gelation .................................52
Table 4: Timeline for Thesis ..............................................................................................63
Table 5: Mean Values for Weights for Raw Patty, Coating Pickup, Pre and
Postfrying, and Weight Difference for Deep-Fried, Battered, and Breaded Chicken
Patties .................................................................................................................................74
Table 6: Main Effect Analysis for Lipid Content (%) for Deep-Fried, Battered, and
Breaded Chicken Patties ....................................................................................................76
Table 7: Main Effect Analysis for Moisture Content (%) for Deep-Fried, Battered,
and Breaded Chicken Patties .............................................................................................81
Table 8: Mean Values for Sensory Color, Evenness of Color, and Greasiness of
Surface Rating and Instrumental Color Values for Deep-Fried, Battered, and Breaded
Chicken Patties...................................................................................................................86
Table 9: Mean Values for Sensory Hardness and Crunchiness, Crust Thickness, and
Instrumental Hardness, Crust Fracture, and Crust Work for Deep-Fried, Battered, and
Breaded Chicken Patties ....................................................................................................91
Table 10: Mean Values for Rating of Mouth Feel Attributes for Deep-Fried, Battered,
and Breaded Chicken Patties .............................................................................................95
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Table 11: Mean Values for Rating of Basic Tastes for Deep-Fried, Battered, and
Breaded Chicken Patties ....................................................................................................96
Table 12: Mean Values for Rating of Flavor Attributes for Deep-Fried, Battered, and
Breaded Chicken Patties ....................................................................................................97
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LIST OF FIGURES
Page
Figure 1: Diagram of liquid in a pore. ...............................................................................29
Figure 2: The CIELAB color space representing the three color coordinates L*, a*,
and b*. ................................................................................................................................57
Figure 3: Flowchart of methodology for optimization of whey protein isolate (WPI)
solution in reducing oil absorption in batter and breaded fried chicken when used as a
postbreading dip. ................................................................................................................62
Figure 4: Average total polar material (%) of oil samples during the frying process
with relation to the number of patties fried. .......................................................................72
Figure 5: Final lipid content (%) for crackermeal-coated patties (CMP) treated at
various pH levels and whey protein isolate (WPI) concentrations. ...................................78
Figure 6: Final lipid content (%) for Japanese breadcrumb-coated patties (JBP)
treated at various pH levels and whey protein isolate (WPI) concentrations. ...................79
Figure 7: Final moisture content (%) for crackermeal-coated patties (CMP) treated at
various pH levels and whey protein isolate (WPI) concentrations. ...................................83
Figure 8: Final moisture content (%) for Japanese breadcrumb-coated patties treated
at various pH levels and whey protein isolate (WPI) concentrations. ...............................84
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CHAPTER 1: INTRODUCTION
This study investigated the effectiveness of a treatment using whey protein isolate
(WPI) as a postbreading dip to reduce the fat content of deep-fried, battered, and breaded
chicken patties. Research towards the reduction of fat content in foods are important
because it could simultaneously fulfill the steady demand for fried foods and contribute
to the growing efforts of Americans to consume less fat.
The Institute of Medicine’s (IOM’s) Acceptable Macronutrient Distribution
Range (AMDR) for fat intake for adults is 20 to 35% of total calories per day. Although
the mean percent of daily calories contributed by fats for all ages is within this range
(32.7%; Breifel & Johnson, 2004), they are on the high end. Since total energy intake has
increased (Gebhardt, et al., 2006), the absolute level of fat intake has risen from 73.4 g in
1989-1991 to 76.4 g in 1994-1996 (Breifel & Johnson, 2004; Chanmugam et al., 2003).
High intake of fat is associated with increased risk for many chronic diseases and
health complications such as cardiovascular disease (Oh, Hu, Manson, Stampfer, &
Willett, 2005), high blood cholesterol levels (Albert & Mittal, 2002), obesity (Howarth,
Huang, Roberts, & McCrory, 2005), diabetes (Thanopoulou, et al., 2003), and some types
of cancer such as breast cancer (Smith-Warner & Stampfer, 2007) and prostate cancer
(Fradet, Meyer, Bairati, Shadmani, & Moore, 1999). The high level of fat intake may be
closely related to the increase of convenient fried food products in the market. Fried
foods contain significant amounts of fats, reaching in some cases one third of the total
food product by weight (Mellema, 2003). As consumers become increasingly aware of
the need to lower their daily fat intake, there is a push towards low- or reduced-fat foods
and beverages (Calorie Control Council, 2006). In light of the demands for low-fat foods,
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research into reducing fat/oil absorption during deep-fat frying may be a strategy that can
help achieve calorie reduction in the American diet.
Methods currently employed to reduce fat absorption in fried foods include
modifications of frying techniques such as shaking and draining of fried foods (Bouchon,
Aguilera, & Pyle, 2003; Mellema, 2003), careful monitoring of frying temperature and oil
degradation (Math, Velu, Nagender, & Rao, 2004), and altering the surface of the food by
reducing the surface area (Goni, Bravo, Larrauri, & Calixto, 1997; Moreira, Sun, & Chen,
1997) or covering the surface with lipid barriers. Most barriers that are used in the
commercial production of fried foods are made from proteins or nonprotein hydrocolloids
such as corn zein, soy protein, albumin, cellulose, and gums (Gennadios, Weller, Hanna,
& Froning, 1996; Mellema, 2003). The mechanisms by which these ingredients are
responsible for oil inhibition are varied and include an increase in water holding in the
product, which reduces the likelihood of steam escape during frying, as observed when
using curdlan (T. Funami, M. Funami, Tawada, & Nakao, 1999), the alteration of surface
hydrophobicity of the product being deep fried (Annapure, Singhal, & Kulkarni, 1999),
and the creation of a hurdle to moisture release and subsequent oil absorption, usually via
the formation of thermally induced gels such as those formed by whey proteins.
Whey protein could potentially be used as a lipid barrier due to its ability to form
thermally induced gels. It is composed of various proteins, the main protein of which is
β-lactoglobulin (β-lac), a globular protein with an isoelectric point of 5.1. This protein
makes up 50-55% of the total protein contained in whey. Other important globular
proteins of whey are α-lactalbumin (α-lac) and bovine serum albumin (BSA). All of these
proteins, particularly β-lac, can form thermally-induced gels that alter the porosity of the
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product, thus lowering moisture loss due to evaporation and subsequent oil absorption
into the fried food when used as a coating (Dogan, Sahin, & Sumnu, 2005; Van Vliet,
Lakemond, & Visschers, 2004). The usage of whey protein as a food coating has long
been investigated and applied (Gennadios, Hanna, & Kurth, 1997; Mellema, 2003).
However, the extent of commercial application of whey protein coatings as oil barriers
has been limited to separating oil-rich products, such as nuts, from other components of
heterogeneous foods such as cereal (Haines, 2004). Hence, this research seeks to expand
the usage of whey protein as a lipid barrier by examining the effectiveness of whey
protein in reducing oil absorption in deep-fried, battered, and breaded chicken patties.
Statement of the Problem
The overall objective of this research is the optimization of a pretreatment to
reduce oil absorption in fully fried, battered, and breaded products by utilizing a solution
of WPI as a postbreading dip. Whey protein coatings may form gels when heated, such
as that during deep frying. Because temperature, concentration of protein, pH, and ionic
strength affect gelation of whey protein due to influences on the rate of denaturation and
aggregation (Belitz & Grosch, 1999), it may be beneficial to study the effects of these
factors on the ability of WPI coatings to reduce fat uptake in fried foods. This current
research focused on the effects of whey protein concentration and pH on fat and moisture
content and organoleptic properties (appearance, taste, texture, and flavor) in fried foods
and determined an optimal pH and protein concentration for the development of a WPI
coating.
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Research Questions
1. What is the optimal pH and concentration of whey protein isolate (WPI) solution
necessary in a postbreading dip to reduce fat uptake in fully fried, battered and
breaded chicken patties?
2. How does the coating affect the chemical (fat and moisture content) and organoleptic
properties (appearance, taste, texture, and flavor) of the product?
Significance of Study
The usage of whey protein as food coatings has long been investigated and
applied (Gennadios et al., 1996; Haines, 2004; Mellema, 2003). However, the extent of
commercial application of whey protein coatings as oil barriers is limited to separating
oil-rich products, such as nuts, from other components of heterogeneous foods such as
cereal (Haines, 2004). Furthermore, application of other types of coatings to reduce oil
uptake are not commercially feasible due to physical, chemical or economical constraints.
A search of available patents on oil-barriers in foods revealed that the technology
involves multiple steps that are time consuming (long postdipping drying time), and use
non-natural chemical additives, or employ treatments that potentially compromise the
quality of the finished product (U.S. Patent No. 4,917,908, 1990; U.S. Patent No.
5,126,152, 1992). The usage of WPI as a postbreading solution requires optimization of
various factors such as pH level and protein concentration. In addition, the final product
should be nutritious and appealing to the senses. The results of this research will
contribute to existing studies on the oil-barrier capabilities of whey protein films and may
become the stepping stone to the commercial application of these coatings on fried foods.
Because whey has many disposal issues, increased utilization of whey will not only
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benefit the dairy industry financially, but also will help decrease the amount of whey that
is being disposed. Fried food manufacturers may also benefit by being able to promote
their foods as being low- or reduced-fat products. Finally, the commercial application of
reduced-fat-frozen-prefried foods might contribute to the reduction of fat intake in the
American diet.
Delimitations and Limitations
There are many factors apart from the independent variables of this study (pH
levels and WPI concentration) that may affect oil absorption in the fried chicken patties,
such as oil quality and composition (Fillion & Henry, 1998), frying temperature and time
(Sahin, Sumnu, & Altunakar, 2005), product composition (Sahin et al., 2005), moisture
content (Sjöqvist & Gatenholm, 2005), shape (Mellema, 2003), porosity (Gamble, Rice,
& Selman, 1987), prefrying treatment (Krokida, Oreopoulou, Maroulis, & MarinosKouris, 2001), surface treatments (Krokida, Oreopoulou, & Maroulis, 2000), initial
interfacial tension (Pinthus & Saguy, 1994), and crust size (Maskat & Kerr, 2002).
Efforts were made to minimize the influence of these factors on the end results and these
included standardization of batter composition and viscosity, and keeping as many frying
parameters constant as possible such as oil degradation, patty weight, batter, breading,
and whey pickup, and frying temperature. Nothing was deliberately done to alter the
product composition (pure chicken breast meat), moisture content, shape, and porosity of
the samples. During statistical analysis, all factors that were suspected to influence the
measured variables were treated as covariants and analyzed using analysis of covariance
(ANCOVA).
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All instrumental analyses were individually performed on randomly selected
patties from each treatment, thus resulting in the large standard deviations due to
preanalytical errors that affect individual patties in addition to errors during analysis.
During statistical analysis of these measurements, all outliers were removed from the
results to account for these errors. Sensory analysis results may be affected by
psychological errors that influenced individual responses. Some of these errors may
include those due to expectation, preference, environment, and fatigue (Stone & Sidel,
1985). The panel was screened and trained for a total of 17, 50-minute sessions to reduce
occurrence of these errors during sampling. In addition, sampling was limited to six
samples per session to minimize the potential for fatigue (Stone & Sidel, 1985). All
samples were randomly selected and served to each panelist immediately upon being
reheated to an internal temperature of 74 °C to minimize variations due to
rethermalization.
Despite the many factors that may influence the oil absorption and organoleptic
properties of the fried chicken patties, this study only focused on the effect of pH and
protein concentration on final lipid content, moisture content, and sensory attributes. This
study used ground chicken breast as the sample medium and results may not be
applicable to other food products such as vegetables due to differences in moisture
content and food matrix structure.
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Definition of Terms
α-lactalbumin: Second most abundant (20-25%) protein fraction in whey,
globular protein with isoelectric point between 4.2 and 4.5.
β-lactoglobulin: Major protein fraction (50-55%) in whey, globular protein with
isoelectric point at around 5.1.
Deep-frying: Frying by submerging food into hot frying medium.
Edible film: Continuous barrier that is formed on to the surface of the foodstuff,
uses ingredients that are safe to eat or Generally Recognized as Safe (GRAS) by FDA.
Globular proteins: A class of protein that is usually spherical in shape, may have
multiple domains, contain hydrophobic core, and have multiple functions (in constrast to
fibrillar proteins that have a structural function).
Isoelectric point: pH at which protein molecules have no net charge and are least
soluble.
Low-fat: Contains less than 3 g of fat and contributes less than 30% of calories
from fat per serving.
Organoleptic: Includes sensory properties of a product, which may involving
taste, color, aroma, and feel.
Par-frying: Blanching or half-frying to an internal temperature of 71 °C, then
cooled and stored.
Reduced-fat: Contains 35% less fat compared to the original version.
Total polar material: Total amount of compounds that are the result of the
breakdown of triglycerides (e.g., diglycerides, monoglycerides, fatty acids, and other
non-triglyceride compounds), measure of oil degradation.
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Whey protein isolate: Whey which was processed to remove most of the lactose
and fat and contains at least 90% protein.
Thermogelation: Gelation induced by heating. Pertaining to protein solutions: As
heat is increased, denaturation occurs and lowers viscosity of the protein solution. This is
followed by aggregation, which increases viscosity, and the resulting product is a gel.
Umami: The fifth basic taste. Applies to the sensation of savoriness, specifically
to the detection of the natural amino acid, glutamic acid, or glutamates.
List of Abbreviations and Acronyms
β-lac: β-lactoglobulin
ANCOVA: Analysis of Covariance
ANOVA: Analysis of Variance
CMP: Crackermeal-coated patties
JBP: Japanese breadcrumb-coated patties
± s. d.: Standard deviation
TPM: Total polar material
WPI: Whey protein isolate
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CHAPTER 2: REVIEW OF THE LITERATURE
Introduction
Consumption of Fried Foods and Fat Intake
The Institute of Medicine’s (IOM’s) Acceptable Macronutrient Distribution Range
(AMDR) for fat intake for adults is 20 to 35% of total calories per day. According to data
obtained from the Third National Health and Nutrition Examination Survey (NHANES
III) and from NHANES 1999–2000, the mean percent of daily calories contributed by
fats for all ages is 32.7% with mean fat intake for ages 2 to 19 being 33.5% (Breifel &
Johnson, 2004; Troiano, Briefel, Carroll, & Bialostosky, 2000). Although these values
show that the average fat intake is within the recommended range, they are on the high
end. In addition, studies using the results from the Continuing Survey of Food Intake by
Individuals (CSFII) for 1994–1996 and 1998) show that fewer than 5% of children and
adults have intakes less than 20% of calories from fats while about 25% of them have
intakes greater than 35% of calories from fats (IOM, 2002). Despite reports that the total
fat intake has decreased from 36% of calories in 1971-1974 to 33% of calories in 19992000, the absolute level of fat intake has increased from 73.4 g in 1989-1991 to 76.4 g in
1994-1996 (Breifel & Johnson, 2004; Chanmugam, et al., 2003). It was suggested that the
decrease of percent of calories from fat is caused by the concurrent increase in total
energy intake (Gebhardt, et al., 2006).
Poor diet and/or unhealthy lifestyles contribute to various chronic health
conditions that negatively affect the quality of life. Three of the top ten leading causes of
death are diet-related, including coronary heart disease (contributes 21.1% of all deaths),
cancer (23.4% of deaths), stroke (6.7% of deaths), and diabetes mellitus (2.5% of deaths;
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Singh, Kochanek, & MacDorman, 1996). All these complications are highly correlated
to fat intake (Gebhardt, et al., 2006). High saturated fats in the diet may lead to an
increase in low-density lipoprotein (LDL) cholesterol concentrations which increases the
risk for coronary heart disease. In addition, diets higher than 35% calories in fat have
been observed to increase the risk of developing breast and colorectal cancer and diabetes
(Bingham & Riboli, 2004; Boyd, et al., 2003; Gebhardt, et al., 2006). Furthermore, the
prevalence of excess body weight, particularly obesity, has long been attributed to high
fat intake.
Recent research has shown that Americans, especially children, are becoming
heavier. Correlation studies conclude that overweight prevalence is related to
consumption of food prepared away from the home (Guthrie, Lin, & Frazão, 2002).
There is also a positive correlation between the number of restaurants per capita and high
body mass index and obesity levels (Chou, Grossman, & Saffer, 2004). Foods consumed
away from home have a higher fat content (Lin, Frazão, & Guthrie, 1999; Nielsen, SeigaRiz, & Popkin, 2002) and are most likely to be fried (Taveras, et al., 2005), thus
contributing to the increasing absolute fat intake for the average American. Fried foods
contain significant amounts of fats, reaching in some cases up to a third of the total food
product by weight (Mellema, 2003).
Consumers increasingly are aware of the need to lower their daily fat intake.
According to a national survey conducted by the Calorie Control Council (2006), 188
million adult Americans (88% of the adult U.S. population) were reported to consume
low- or reduced-fat foods and beverages and two-thirds of adults believe there is a need
for food ingredients that can replace the fat in food products. The food industry has
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responded to consumer demand by offering an ever-increasing variety of low-fat eating
choices. In 2001, 7.4% of new food products launched worldwide claimed to contain
reduced levels of fat, and this rose to 10.4% in 2005 indicating an increase in low- or
reduced-fat food demand (Datamonitor Plc., 2006). Examples of low- or reduced-fat
foods include ice creams made with skim milk instead of whole milk, leaner cuts of
meats used in frozen entrees, and potato chips and other salty snacks that are baked
instead of fried. Despite the trend towards lower fat foods, health problems related to
high fat intake are still on the rise. This is probably due to the increasing trend to
patronize fast food restaurants where deep-fat frying is one of the most popular methods
of cooking. In addition to frequent visits to fast food outlets and restaurants, the
consumption of snack foods which include deep fried foods, are high (Kuchler, Tegene,
& Harris, 2004). Kuchler et al. (2004) reported that up to 95.5% of household surveyed
purchase and consume chips (potato, corn, and tortilla). This totals to 16.34 lbs of deepfried chips per year. Due to the growing effort of Americans to consume less fats and the
increasing demand for fried foods, research into reducing fat/oil absorption during deepfat frying might be a strategy to achieve calorie reduction in the American diet.
Battered and Breaded Foods
The popularity of battered and breaded food products has risen worldwide. For
example, according to a study done by Leatherhead Foods, a UK based research firm,
demand for coated foods in Europe is worth €3.46 billion and increased an estimated
18% between 2004 and 2008 (Patton, 2005). Preparation of battered and breaded fried
foods involves a series of steps. After the substrate (e.g., chicken) is washed, the product
may be predusted. Predusts are usually made up of flour to absorb moisture on the
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surface of the product, thus allowing better adhesion of the batter (Yang & Chen, 1979).
In addition, gums, starches and proteins used alone or in combination can also absorb
moisture from the surface of the product (Kuntz, 1997). Next, the food product is coated
with liquid batter and then placed into contact with a breading material such as
breadcrumbs or flour. The food product may be packaged raw, par-fried or fully fried
(U.S. Patent No. 5,126,152).
Breading differ in size, composition, and texture. Typical breading types that are
currently used in the food industry are sheeted breadcrumb products such as crackermeal,
white breaders, and colored breaders, American style breadcrumbs, and Japanese
breadcrumbs or Panko. Sheeted breadcrumb products are produced by rolling out dough
that are then baked before being ground to produce firm and dense particles. The
composition of the dough varies according to the type of breading. For example,
crackermeal only consists of flour and water, while white breaders may also include
browning agents, leavening agents, salt, oil, and flavorings. American style breadcrumbs
are made from dried bread. The crumbs are spiracle, dense, and crunchy. Japanese
breadcrumbs are produced from loaves of dough that are baked in a unique process
known as dielectric baking where electric current is passed through the loaves to generate
heat. The resulting crumbs are porous, pale in color, and light. Japanese breadcrumbs are
generally larger compared to American style breadcrumbs and sheeted breadcrumb
products (U.S. Patent No. 4,943,438).
26
Theories of Oil Uptake in Fried Items
Stages of Deep-Fat Frying
Deep fat-frying can be described in four stages (Farkas, Singh, & Rumsey, 1996).
The first stage is known as the initial heating stage. During this stage, the temperature of
the surface of the food rises to the boiling temperature of the surface water. This stage is
short, lasting for about 10 s, and is marked by negligible lost of mass (water) and heat is
transferred via natural convection. The second stage is known as surface heating. The
heat transfer mechanism changes from natural convection to forced convection as surface
water reaches boiling temperature and is turned to vapor. The change to forced
convection increases the heat transfer coefficient and thus, heat transfer into the food is
faster. This stage marks the beginning of crust formation. The next stage is the falling
rate stage and is the longest of all the stages. Most of the moisture is lost in this stage as
the core region approaches boiling point of water. Towards the end of this stage, the rate
of vapor mass transfer steadily decreases due to the low amount of free water and
continued thickening of the crust that acts as a barrier for rapid vapor release. The final
stage is the bubble end point. This stage is characterized by the apparent cessation of
moisture loss from the food during frying. This may be caused by several factors ranging
from the complete removal of all liquid water in the sample, such as with potato chips, to
a reduction in heat transfer to the crust/core interface. The dryness and porosity of the
crust lowers its thermal conductivity, which decreases heat transfer into the food.
27
Mechanisms of Oil Absorption
According to Dana and Saguy (2006), there are three proposed mechanisms
explaining oil uptake in fried foods, namely water replacement, cooling-phase effect, and
surfactant theory of frying.
Water Replacement
According to this mechanism, oil absorption is the result of the replacement of
evaporated water with cooking oil during the frying process. When food is immersed in
oil that is heated to above the boiling temperature of water, moisture near the surface of
the food is almost instantly converted to steam. This leaves pores on the surface of the
food. When the void is large enough, positive vapor pressure is very low and this allows
oil to enter into the food. However, this is restricted to large voids near the surface of the
food (i.e., the crust region). This mechanism is able to explain the direct relationship
observed between water loss and oil uptake observed during the frying process (Pinthus
& Saguy, 1994; Rice & Gamble, 1989). However, many studies have shown that oil
absorption occurs mainly during the cooling phase (Bouchon et al., 2003; Moreira et al.,
1997; Pinthus & Saguy, 1994) and thus, this mechanism taken alone is inadequate in
explaining the totality of oil absorption in fried foods.
Cooling-Phase Effect
After the food is fried and removed from the hot oil, the food cools and this
results in water vapor condensation which decreases the internal pressure of the pores
that develop during the frying process. The sudden drop in pore pressure creates a
vacuum effect that sucks the oil that adhered to the surface into the pores. This
mechanism relies heavily on the relationship between oil uptake and the surface of the
28
food. Oil intake is restricted to the immediate crust and product surface and is largely
dependent on crust microstructure (Pinthus & Saguy, 1994) and oil viscosity (Dana &
Saguy, 2006). Since oil uptake via the cooling-phase effect is highly dependent on the
surface of the food, this mechanism could be further explained using surface chemistry,
particularly wetting, capillary penetration and displacement (Pinthus & Saguy, 1994).
Wetting deals with the affinity of a fluid for a solid: Fluid with low affinity will form
beads on the surface of the solid, and fluid with high affinity will form a film on the
surface (Miller & Neogi, 1985). Wettability is dependent on the contact angle, interfacial
tension, and the radius of the pores. The relationship between these three properties with
capillary pressure is represented in Equation 1 and is shown in Figure 1 (Adamson &
Gast, 1997).
Pc = Pnw − Pw =
2γ cos θ
r
(1)
The wetting fluid, which in this case is the frying medium, will continue to enter a
pore until there is an opposing pressure, the pressure from the non-wetting fluid (Pnw),
that matches that of the pressure exerted by the wetting fluid (Pw). An example of an
opposing pressure would be the pressure from the trapped vapor in the pore. As described
by the capillary pressure (Pc) equation, this is dependent on the interfacial tension
between the gas or air and liquid (γ), contact angle between the surface and the liquid (θ),
and the inner radius of the pore (r). If the contact angle is greater than 90°, the liquid does
not wet the solid and tends to move about on the surface and not enter the capillary pores.
The liquid completely wets a solid only when the angle is zero (Adamson & Gast, 1997).
29
Figure 1. Diagram of liquid in a pore. In this diagram, the meniscus is part of a circle
with radius R. The capillary pressure is the net pressure contributed by the opposing
pressure of the non-wetting phase (Pnw) and the wetting phase (Pw). In deep-fat frying, the
non-wetting phase is the water vapor while the wetting phase is the frying medium.
________________________________________________________________________
Note. From Physical Chemistry of Surfaces (p. 12), by A. W. Adamson and A. P. Gast,
1997, New York: Wiley Interscience. Copyright 1997 by John Wiley & Sons, Inc.
Adapted with permission.
In addition to contact angle values, the oil would more likely enter a pore if the
radius of the pore is large and/or if the interfacial tension is low. Upon removal of the
food from the frying oil, the interfacial tension between oil and air within the pores
increases as temperature decreases and causes surface oil to flow rapidly into pores
(Moreira et al., 1997). Bouchon et al. (2003) studied the relationship between the amount
of oil that penetrated the surface postfrying and oil left on the surface and found that the
amount of surface oil that enters the food increased with frying time, mostly probably due
30
to the increased formation of pores within the crust. While oil absorption was restricted
in regions closer to the surface, the distribution of oil absorption was not even, reflecting
the probability of the influence of local microstructural differences (Saguy, Gremaud,
Gloria, & Turesky, 1997). Based on these results, it was suggested that the microstructure
(mean pore size, connectedness, permeability) of the crust region is the single most
important product-related determinant of oil uptake into the food.
Although the cooling-phase effect mechanism only deals with oil absorption
postfrying, many studies have shown that oil absorption is the highest during the cooling
phase, although it does not account for all the oil absorption in fried foods. In fact, 80%
of oil absorbed in fried tortilla, frozen, par-fried potatoes during refrying and in french
fries (Aguilera & Gloria-Hernandez, 2000; Moreira et al., 1997; Saguy et al., 1997;
Ufheil & Escher, 1996). This may be due to the slower pressure build-up when frying at a
lower temperature, which facilitates capillary diffusion of oil. During cooling, fries
cooled at a lower temperature (25 °C) absorbed oil faster than those cooled at a higher
temperature (80 °C) because higher cooling temperature induces a smaller capillary
pressure difference (Yamsaengsung & Moreira, 2002).
Since the characteristics of the surface of the fried product is important in
determining the amount of oil that enters the product in accordance to the cooling-phase
mechanism, any modifications of the surface microstructure will affect oil absorption.
These modifications will have a significant impact on oil absorption because many
studies have shown that the highest oil uptake is during the cooling phase (Aguilera &
Gloria-Hernandez, 2000; Moreira et al., 1997; Saguy et al., 1997; Ufheil & Escher,
1996).
31
Surfactant Theory of Oil Absorption
The surfactant theory attributes increased oil uptake to the generation of
surfactants especially in aging oil (Blumenthal & Stier, 1991). Oil absorption during
frying or postfrying is largely dependent on interfacial tension between oil and water and
contact angle (Dana & Saguy, 2006). As the frying process progresses, the oil degrades
and this changes the composition of oil from 96 to 99% triglycerides to a mixture of
compounds (e.g., diglycerides, monoglycerides, free fatty acids, and glycerol; Paul &
Mittal, 1997). These breakdown compounds act as surface-active agents that serve to
lower the interfacial tension between the oil and the water (Dana & Saguy, 2006).
In support of this mechanism, it has been observed that these breakdown
compounds (especially monoglycerides) cause a significant decrease in interfacial tension
in oil/water systems between frying oil and water due to their degree of unsaturation and
molecular structure (Feuge, 1947; Gaonkar, 1989; Gaonkar & Borwankar, 1991). Gil and
Handel (1995) did a study on the effect of monoglycerides of differing degrees of
saturation on interfacial tension in oil and water systems and found that interfacial
tension decreased as the degree of saturation increased. They concluded that monostearin,
which has no double bond, can align at the interface more compactly due to an absence of
a kink in the structure as compared to monoolein and monolinolein, which have one
double bond and two double bonds, respectively. While some investigators have shown
that oil absorption increased with degradation (Dana & Saguy, 2006), others have
observed either no significant increase in oil absorption (Dobarganes, Márquez-Ruiz, &
Velasco, 2000) or a decrease in oil uptake (Moreira et al., 1997). The inconsistent results
obtained by various studies suggest that the surfactant theory may only apply for certain
32
oil and product conditions such as oil type and composition of fried food (Dana & Saguy,
2006). Nevertheless, this mechanism cannot be ignored, because it was observed to have
an effect on oil absorption in some studies.
In conclusion, none of the mechanisms, taken alone, adequately explain the
complexity of oil absorption in fried foods. While many studies showed that most of the
oil absorption occurs during the cooling phase, they also show that some of the oil is
taken up during frying (water replacement mechanism), and that there is a correlation
between degradation of oil and oil uptake (surfactant theory of oil absorption). In
addition, all of these mechanisms show the strong dependence of oil absorption on the
microstructure and surface characteristics of the product.
Factors Affecting Oil Absorption
There are many factors affecting oil absorption in fried foods. These can be
roughly classified into two categories: (a) those that are intrinsic properties of the food
being fried such as product composition, moisture content, shape, porosity, initial
interfacial tension, and crust size, and (b) those that are part of the frying process such as
oil quality and composition, frying temperature and time, and frying methods (Albert &
Mittal, 2002; Fillion & Henry, 1998; Gamble et al.,1987; Krokida et al., 2000; Krokida et
al., 2001; Maskat & Kerr, 2002; Mellema, 2003; Pinthus & Saguy, 1994; Sahin et al.,
2005). Identifying these factors would help in the development of processes that would
lead to a lower final fat content.
33
External Factors Affecting Oil Absorption
Composition of the Frying Oil
Frying oil may differ in degree of saturation and fatty acid composition.
Nutritionally, it is recommended that frying fats should be low in saturated fats and transfat and high in unsaturated fats. However, saturated fats are more stable and are preferred
in deep-fat frying to maintain food quality (Stier, 2004). Choosing a suitable frying
medium is important in controlling fat absorption in fried foods although it is a minor
factor in oil absorption compared to the intrinsic properties of the product that is being
fried (Dobarganes et al., 2000). Based on the surfactant theory of oil absorption, a
suitable frying oil that will reduce the final fat uptake will be one that reduces lipid
oxidation since this will lessen the degree of oil degradation, such as oils that are rich in
oleic acid, a monounsaturated fatty acid (Abdulkarim, Long, Lai, Muhammad, &
Ghazali, 2005; Ngadi, Li, & Oluka, 2007; Romero, Cuesta, & Sanchez-Muniz, 2000).
However, Krokida et al. (2000) found no difference in fat uptake when french fries were
fried in oil with different concentrations of hydrogenated oil. The inconsistency of the
effect of the degree of hydrogenation of frying oil suggests that the properties of the
frying medium may not have a significant impact on oil absorption.
Frying Time and Temperature
Monitoring frying time and temperature has been practiced in the frying industry
to ensure the consistent quality of fried foods. This may be attributed to the increased
formation of surfactants due to oil degradation and its relation to oil uptake. Fat content
was shown to increase with frying time in both coated and uncoated foods (Makinson,
Greenfield, Wong, & Wills, 1987) until it reaches an equilibrium (Krokida et al., 2000).
34
Foods fried at high temperatures have been observed to have less oil uptake and this may
be due to the quick pressure buildup when frying at high temperatures, which prevented
capillary diffusion of oil (Yamsaengsung & Moreira, 2002).
Postfry Handling
As mentioned before, oil is actively absorbed into the product once it is removed
from the frying medium. Oil absorption postfrying is related to the amount of oil
remaining on the food surface and can also be affected by cooling temperatures. More
viscous oil (due to degradation) tends to cling better to food surfaces and increase the
chances of being absorbed into foods (Mackay, 1999) while cooling fried foods at low
temperatures promotes fat uptake (Yamsaengsung & Moreira, 2002). Thus, practices
such as shaking or draining fried foods which physically remove the oil from the food
surface might help reduce oil absorption.
Intrinsic Factors Affecting Oil Absorption
In general, foods that have lower initial moisture content will result in a higher
final fat content (Gamble et al., 1987). Many studies have shown the dependence of fat
uptake on initial moisture content and loss (Gamble et al.; Mellema, 2003). Another
related factor is the initial fat content of the food being fried. This is because there is a
need for a concentration gradient for fat absorption to take place from the surroundings
into the product (Ateba & Mittal, 1994). According to a study done by Mai, Shimp,
Weihrauch, and Kinsella (1978), the higher the fat content of the fish (e.g., trout), the less
lipid change is induced by frying. Makinson et al. (1987) showed that higher amounts of
fat were absorbed if the substrate is of a plant origin that naturally has a higher moisture
content and lower fat content.
35
Components of foods that have been shown to have a significant impact on fat
uptake are protein level, type of starch, and the presence of hydrocolloids. Overall, higher
protein content results in lower final fat content due to the ability of protein to retain
moisture (Salvador, Sanz, & Fiszman, 2005). The effect of protein is dependent on the
nature of the major protein fraction. More lipophobic proteins, such as ovalbumin, may
decrease oil absorption while more lipophilic proteins, such as lipoproteins and
phosphoproteins found in egg yolk, may emulsify oil and water into the fried product
(Mohamed, N. A. Hamid, & M. A. Hamid, 1998). Even though addition of emulsifiers in
batters increased oil absorption, excess amounts were actually shown to decrease oil
uptake (Mohamed et al., 1998). Batters made with soy, egg albumin, and whey protein
were observed to reduce oil absorption either due to improved water vapor barrier
properties and/or through imparting lipophobic properties to the batter (Dogan et al.,
2005). Fat uptake in starchy foods depends on the amylose/amylopectin ratio of the flours
used and particle size since they influence porosity and moisture content. Flour with
smaller particle size tends to form a thick crust very early in the frying process, thereby
impeding the transfer of heat to inner portions of the fried foods and less moisture is
evaporated (Singh, Hung, Phillips, Chinnan, & McWatters, 2004). Furthermore, smaller
particles form smaller pores with higher capillary pressure, leading to a reduction in oil
uptake (Moreira et al., 1997).
Methods for Reduction of Oil Absorption
Because initial moisture content is a factor in the absorption of oil during frying,
prefry drying is a method that has been shown to reduce final fat content in fried foods
(Debnath, Bhat, & Rastogi, 2003; Pedreschi & Moyano, 2005). In a study on fried potato
36
chips, Lamberg, Hallstorm, and Olsson (1990) found that drying the potato chips prior to
deep-fat frying reduced the fat uptake up to 49%. However, variations in prefry drying
methods also play a role in determining final oil uptake. Prefry drying via microwave or
hot air drying was observed to lower oil absorption but freeze drying increased oil uptake
(Gamble et al., 1987). Freeze drying causes an even distribution of moisture and when
freeze-dried food is fried, moisture loss occurs evenly over the surface and results in even
oil covering (Gamble et al., 1987). Microwave drying and air drying gives a
heterogeneous moisture distribution, and oil absorption is only limited to areas with low
moisture content. Methods that increase starch granule integrity have been shown to
reduce oil uptake in starchy fried foods. Blanching potato with calcium chloride was
observed to lower oil absorption because pectic enzymes in the potato react with calcium
ions to create more rigid structure and increases the firmness of the cell wall. This
decreases leaching of starch granule content and reduces oil absorption into the granules
(Rimac-Brnčic´, Rade, & Šimundic´, 2004).
Research in the development of lower fat products has focused on physical
modification of the food product (Mellema, 2003) such as decreasing surface area and
coatings. In general, products with a larger surface area have a higher final fat content
compared to products with smaller surface area. Greenfield, Makinson, and Wills (1992)
found that decreased fries size significantly increased fat content of fries in a linear
fashion due to a higher surface area. Potato chips that were cut thin and had rough
surfaces had a higher fat uptake than potato chips that were thicker and had smoother
surfaces (Goni et al., 1997; Keller, Escher, & Solms, 1990). Other modifications that
have been done on fried food surface include application of coatings or batter using
37
various compositions (Gennadios et al., 1997). According to Makinson et al. (1987),
batter-coated products absorbed less oil than uncoated fish sticks, while breading alone
did not significantly change the total fat uptake of the fish. Presence of batter apparently
resulted in the formation of a hard crust, which was impervious to the movement of water
and fat. Hence, water loss and fat absorption were reduced during frying (Fillion &
Henry, 1998). Properties of coatings that are beneficial to reducing fat intake include low
moisture content, low moisture permeability, thermogelling or crosslinking. Coatings
should have low moisture content because oil uptake is dependent on the moisture
content of the surface of the fried food (Lamberg et al., 1990; Moreira et al., 1997). Low
moisture permeability in coatings helps to reduce water loss and thus, reduces oil uptake.
However, too much of this property may result in soggy foods. (Mellema, 2003).
Thermogelling or crosslinking results in high gel strength and leads to lower water
diffusivity. Thermogelling or crosslinking also promotes the formation of wide punctures
with low capillary pressures (Mellema, 2003).
Nonprotein-Based Coatings or Films
Another method of modifying the surface of fried products is the application of
edible films and coatings. Both can be applied to the product via spraying, immersion, or
direct application (Rayner, Ciolfi, Maves, Stedman, & Mittal, 2000). Edible films and
coatings have been used commercially as coverings on fresh produce, candy, meats, nuts,
cereal, and so forth (Albert & Mittal, 2002; Gennadios et al., 1997). According to a
review done by Gennadios et al. (1997) on the application of edible films and coatings on
meats, the use of coatings can help prevent moisture loss during storage of fresh meats,
reduce lipid oxidation, minimize load of spoilage and pathogenic microorganism, restrict
38
odor pick-up, and reduce oil uptake in battered and breaded fried products. The most
common nonprotein edible films and coatings are made up of lipids such as waxes and
glycerides, and polysaccharides (Gennadios et al., 1997; Morillon, Debeaufort, Blond,
Capelle, & Voilley, 2002) or a combination of both (Coughlan, Shaw, J. F. Kerry, & J. P.
Kerry, 2004; Phan, Debeaufort, Luu, & Voiley, 2005).
While lipid-based films and coatings are not typically used as lipid barriers,
polysaccharides are probably the most studied edible films for reduction of oil
absorption. Garcia, Ferrero, Bértola, Martino, and Zaritzky (2002) did a study using
methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) as an edible coating to
reduce oil uptake in deep fried potato strips. They found that a mixture of MC with
sorbitol was effective in reducing oil absorption by 40.6% compared to uncoated potato
strips. Williams and Mittal (1999) compared the oil barrier properties of gellan gum, MC
and HPMC and found that MC was most effective in reducing oil absorption (91%
reduction). They also tested the effect of film thickness of gellan gum on moisture and fat
content. They observed that moisture loss decreased as film thickness increased. Fat
absorption was reduced overall compared to uncoated samples. However, the effect of
film thickness was not apparent.
Alginates, extracted from seaweed, are salts of alginic acid and are linear copolymers of D-mannuronic and L-guluronic acid monomers (Gennadios et al., 1997).
Unfortunately, alginates exhibit high water vapor permeability because they are
hydrophilic polysaccharides and for practical purposes, are often mixed with calcium,
which acts as a gelling agent. Krochta and de Mulder-Johnston (1997) studied the oilbarrier property of alginates mixed with calcium chloride (CaCl2) and found that it was
39
impervious to oils. Another extract of seaweed that could be used as an oil-barrier is
carrageenan, a galactose polymer. Annapure et al. (1999) found that a 2% carrageenan
coating for chick pea dough showed a 17% reduction in oil uptake. They ranked the
ability for fat reduction of several non-protein hydrocolloids: gum arabic > carrageenan >
gum karaya > guar gum > carboxymethylcellulose > hydroxypropylmethyl cellulose
where hydroxypropylmethyl cellulose such as xanthan and locust bean gum hardly
showed any reduction in fat absorption at all.
Gellan gum is a polysaccharide manufactured by microbial fermentation of the
Sphingomonas elodea microorganism. When used as a mixture with soy protein isolate,
the film was found to reduce fat absorption of fried doughnut mix by 55% (Rayner et al.,
2000). Rayner et al. (2000) also did a texture analysis and found no significant difference
between the coated and uncoated fried food. Bajaj and Singhal (2007) observed a
reduction of fat uptake from 37% to 28% when batter is mixed with gellan gum at 0.25%
(w/w). William and Mittal (1999) prepared a coating made up of 2% gellan gum and
0.5% CaCl2. They observed a reduction of 60% when pastry flour mix product is coated
with this solution and deep-fried.
Nonprotein coatings have been used in industry longer than protein-based
coatings. An example of a commercial edible oil-barrier that is in the market is
Kelcogel® which is produced by CP Kelco (Decision News Media, 2004). This product
is made from gellan gum which is an FDA-approved stabilizer and thickener. When
mixed with mono- or divalent salts, they form films that have good barrier capabilities.
Other nonprotein based oil barriers that are in the market now are methylcellulose and
40
hydroxypropyl cellulose, manufactured by Dow Chemical Co. and Watson Foods, and
they have been used to decrease oil absorption in french fries and onion rings.
Many studies have been conducted to compare the properties of different
compositions of films and coatings (Bozdemir & Tutas, 2003; Coughlan et al., 2004;
Morillon et al., 2002). However, the requirements of edible films and coatings are the
same regardless of material; they must provide a good barrier against oxygen, have good
mechanical properties to allow various manipulations of the food product, and have low
water-vapor permeability (Gennadios et al., 1997). In fried foods, edible films or coatings
must not only fulfill all these requirements, but also are expected to have the ability to
reduce fat uptake. A list of research on the effectiveness of hydrocolloids an oil-barrier in
fried foods can be found in Table 1.
Table 1 (continued on page 42)
Examples of Nonprotein Ingredients Used in Formulations for Reduction of Oil
Absorption in Fried Foods
Ingredient
Fat
reduction
(%) *
Usage
Product
2% in batter
Fried falafel
balls
8.5
Pinthus, Weinberg,
and Saguy (1993)
Methylcellulose 1% in batter
(MC)
Fried falafel
balls
46.4
Pinthus et al. (1993)
2% in batter
Fried, breaded,
and marinated
chicken strips
6.5
Holownia, Chinnan,
Erickson, and
Mallikarjunan (2000)
1% MC + 0.75%
sorbitol coating
solution
Fried wheat
dough balls
29.9
Suárez, Campañone,
García, and Zaritzky,
(2008)
2% MC + 0.2%
polyethylene
glycol film
Fried mashed
potato balls
83.6
Mallikarjunan,
Chinnan,
Balasubramaniam,
and Phillips (1997)
0.25-2% in
batter
Deep-fat fried
foods
9.8-3.0
Annapure et al.
(1999)
0.25-1% in
batter
Fried papad
1.7-19.5
Patil, Singhal, and
Kulkarni (2001)
2% in tortilla
chips
Tortilla chips
5-40
Deep-fat fried
foods
12.6-7.8
Annapure et al.
(1999)
Fried breaded
marinated
chicken strips
4.8
Holownia et al.
(2000)
Cellulose
Carboxymethylcellulose
Hydroxypropyl- 0.25-2% in
methylcellulose batter
(HPMC)
2% in batter
Reference
Esturk, Kayacier, and
Singh (2000)
0.25-1% in
batter
Fried papad
2.2% HPMC +
0.5%
polyethylene
glycol film
Fried chicken
balls
Up to
33.7
Balasubramaniam,
Chinnan,
Mallikarjunan, and
Phillips (1997)
2% HPMC +
0.2%
polyethylene
glycol film
Fried mashed
potato balls
31.4
Malikarjunan et al.
(1997)
0.25-2% in
batter
Deep-fat fried
foods
9.7-8.2
Annapure et al.
(1999)
0.25-1% in
batter
Fried papad
9.7-22.0
Patil et al. (2001)
Locust bean
gum
0.25-2% in
batter
Deep-fat fried
foods
3.4-4.8
Annapure et al.
(1999)
Carrageenan
0.25-2% in
batter
Deep-fat fried
foods
3.4-15.7
Annapure et al.
(1999)
0.25-1% in
batter
Fried papad
2.8-12.0
Patil et al. (2001)
0.25-2% in
batter
Deep-fat fried
foods
8.4-4.4
Annapure et al.
(1999)
Guar gum
Xanthan gum
17.2-2.4
Patil et al. (2001)
Note. *Fat reduction compared to control.
Protein-Based Coatings or Films
Coatings or films made from protein are good barriers to oxygen and lipid, but
they exhibit relatively high water vapor permeability values (Gennadios et al., 1997;
Ustunol & Mert, 2004). The limited resistance of protein films and coatings to water
vapor transmission is attributed to the hydrophilic nature of proteins and to substantial
amounts of hydrophilic plasticizers, such as glycerin and sorbitol, incorporated into films
to impart adequate flexibility (Gennadios et al., 1997; McHugh, 2000). However,
moisture-barrier properties of protein films and coatings can be improved by
incorporating hydrophobic materials such as lipids to produce protein-lipid emulsion
films. When forming these films or coatings to be used as lipid barriers, it should be
noted that excess protein may reduce crispness and increase oil uptake by emulsifying
more oil and water into the fried product (Mohamed et al., 1998).
Corn zein and soy protein are examples of coating ingredients from plant sources
that have been used as oil barriers. Malikarjunan et al. (1997) saw a 59% reduction in
potato balls coated with corn zein solution (15% corn zein in ethanol). Another example
of plant protein used as an edible film in inhibiting oil absorption is gluten (Gennadios,
Weller, & Testin, 1993; Park & Chinnan, 1995). Whey protein and other milk proteins,
such as casein, are examples of coating ingredients that have been shown to have oilbarrier capabilities. Banerjee and Chen (1995) showed that whey protein concentrate gels
had good water vapor barrier (better than that made from WPI and casein) and
mechanical properties (stretchable), while addition of monoglycerides decreased water
vapor permeability by 200% (Anker, Brensten, Hermansson, & Stading, 2002). In
addition, the monoglyceride acted as a plasticizer, which created a desirable increase in
the fracturability of the film. Dough balls that were dipped in soy protein isolate (SPI)
and whey protein isolate (WPI) mixed solution and dried to create a layer of protein film
surrounding the product were observed to have the highest fat uptake reduction (99.8%)
compared to dough balls treated with other combinations of proteins including gelatin,
gellan gum, κ-carrageenan-konjac-blend, locust bean gum, methyl cellulose,
microcrystalline cellulose, pectin, sodium caseinate, and vital wheat gluten. Purified
whey protein adjusted to pH 7.0 using sodium hydroxide was observed to reduce fat
uptake by 5% when applied on blanched potato chips before being deep-fried (Aminlari,
Ramezani, & Khalili, 2005). Other sources of animal protein-based coatings are gelatin
(Arvanitoyannis, Psomiadou, Nakayama, Aiba, & Yamamoto, 1997) and egg albumin
(Gennadios et al., 1996; Handa, Gennadios, Hanna, Weller, & Kuroda, 1999). Some
examples of protein films or coatings that were used as lipid barriers in fried foods as
found in literature are listed in Table 2.
Table 2
Examples of Protein Ingredients Used in Formulations in Reduction of Oil Absorption in
Fried Foods
Fat reduction
(%)*
Reference
Coating
Formulation
Food model
Soy
protein
10% soy protein +
0.05% gellan gum
film
Fried doughnut
disks
Corn
Zein
14% corn zein +
2.8% glycerin film
Fried mashed
potato balls
59
Casein
3% sodium caseinate
protein film
Potato chips
13.6
Aminlari et al.
(2005)
Whey
protein
3% whey protein
film
Potato chips
4.8
Aminlari et al.
(2005)
Albumin 3% albumin film
Potato chips
12.1
Aminlari et al.
(2005)
Note. *Fat reduction compared to control.
55.12
Rayner et al.
(2000)
Mallikarjunan et
al. (1997)
Protein Gelation
In order for a protein to undergo gelation, it must first go through denaturation.
Denaturation is used to describe a reversible or irreversible change of molecular structure
of a protein without cleavage of covalent bonds except for the disulfide bridges (Belitz &
Grosch, 1999). This can be initiated by changes in temperature and pH, increases in the
interface area, or the addition of organic solvents, salts, urea, guanidine hydrochloride or
detergents (Belitz & Grosch, 1999). During denaturation, side chains of the amino acid
are exposed and undergo intermolecular interactions. They form small spherical
aggregates which combine into linear strands that interact to create a gel network
(Fitzsimons, Mulvihill, & Morris, 2007). If the unfolding of the peptide chain is
stabilized by interaction with other chains such as interactions between exposed reactive
groups (e.g., thiol groups), the denaturation process would be irreversible (Belitz &
Grosch, 1999). The ratio of the rate of denaturation with the rate of aggregation
determines the gel characteristics (Belitz & Grosch, 1999). If the rate of aggregation is
slower in comparison with the rate of denaturation, the resulting gel will be a finer
network of protein chains, less opaque, and less capable of holding on to water due to
smaller voids between molecules (Gossett, Rizvi, & Baker, 1984).
Factors affecting protein gelation. Gelation of protein is affected by factors that
influence the rate of denaturation and aggregation such as temperature, concentration of
protein, pH and ionic strength (Belitz & Grosch, 1999). Temperature and heating rate can
affect both the rate of denaturation and the rate of protein-protein interaction (Belitz &
Grosch, 1999). The temperature above which a gel will not form is known as the critical
gelation temperature, which is directly proportional to heating rate (Li, Ould Eleya, &
Gunasekaran, 2006; Tosh & Marangoni, 2004). While there is a critical (maximum)
gelation temperature, there is no indication for the existence of a minimal temperature of
gelation (Le Bon, Nicolai, & Durand, 1999). However, below critical gelation
temperatures, the time required for the formation of the gel will decrease (Tosh &
Marangoni, 2004). In the case of forming gels for coatings, the aggregation rate should be
slower than the unfolding rate to avoid forming coarse and unstructured gels (Belitz &
Grosch, 1999).
Besides heat, protein concentration also determines the characteristics of the gel
and the likelihood of it being formed. Generally, the elastic properties of the gel network
vary depending on protein concentration (Puyol, Perez, & Horne, 2001). When the level
of protein is too low, a protein network is difficult to establish because protein-protein
interactions tend to occur within molecules rather than between molecules (Belitz &
Grosch, 1999). As the protein content increases, the likelihood of intermolecular
crosslinks increases and gelation is more likely to occur. The critical protein
concentration for gelation is dependent on pH and ionic strength. For example, the
critical concentration for β-lac is a minimum at the isoelectric point (5.1) and is
independent of ionic strength. At other pH values, the critical protein concentration varies
inversely with ionic strength (Puyol et al., 2001).
As mentioned before, pH can have a marked effect on the structure of proteins. At
pH levels far away from the isoelectric point, the protein is highly charged (Belitz &
Grosch, 1999). Hence, the association or aggregation of the protein molecules is difficult
to achieve due to electrostatic repulsion even upon heating. However, aggregation and
gelation can occur at high enough protein concentrations and/or high ionic strength
(Schokker, Singh, Pinder, & Creamer, 2000). If the pH is adjusted towards the isoelectric
point, the charge on the protein molecules will be reduced, promoting aggregation
(Fitzsimons et al., 2007). However, these aggregates are colloidally stable at ambient
temperature; thus, formation of gels at the isoelectric point can only be achieved when
heated (Ju & Kilara, 1998). Under conditions of strong electrostatic repulsion (away from
isoelectric point), whey protein gels are transparent, and have a fine-stranded structure. In
conditions of weak electrostatic repulsion, whey protein gels become more opaque and
coarser with bigger pores (Puyol et al., 2001). Differences in gel structure not only are
influenced by electrostatic interactions, but also may be due to the dependence of rate of
denaturation and aggregation on pH level. Thus, pH of the protein solution should be
adjusted to achieve proper balance between the rate of denaturation and aggregation that
is needed for gel formation (Belitz & Grosch, 1999).
Salts in general can affect the structure of protein molecules as well as the nature
of protein-water interactions by changing the ionic strength of the protein solution
(Chantrapornchai & McClements, 2002). These effects influence both the solubility of
protein and their rate of thermal denaturation. As with temperature and concentration,
there is generally an optimal level of salt that favors gel formation (Belitz & Grosch,
1999). In their study on the effect of salt concentration in heat induced whey protein gels,
Chantrapornchai and McClements (2002) found that at neutral pH (pH 7), the gels went
from fairly fine grained and homogeneous to coarse grained and porous with an increase
in salt concentration. The gels formed at high salt concentrations exhibited increased
water loss. The lack of gelation at low salt concentration at neutral pH may be due to the
high electrostatic repulsion between highly negatively charged molecules (Bryant &
McClements, 1998). The addition of salt increases the ionic strength of the solution
which promotes interaction of the charged protein molecules through charge shielding
(Belitz & Grosch, 1999). However, salt only has a significant effect on properties of
protein gels when it is added prior to heating (Boye, Alli, & Ismail, 1996; Foegeding,
Bowland, & Hardin, 1995; Langton & Hermansson, 1992).
Whey Protein
Whey is the watery portion of milk remaining after milk coagulation and removal
of the curd. Whey can be obtained by acid, heat, and rennet coagulation of milk. There
are two kinds of whey: Sweet whey and acid whey. Sweet whey is manufactured during
making of rennet type hard cheese like cheddar or Swiss cheese and has a pH level of
more than 5.6. On the other hand, acid whey or sour whey is obtained during making of
acid type of cheese such as cottage cheese and has a pH level of less than 5.1. Both types
of whey contain about 0.7 to 0.8% protein on a liquid basis (Dairy Management, Inc.,
2005). On average, about 90% of the milk used for cheesemaking ends up as whey (S.
Bhattacharjee, C. Bhattacharjee, & Datta, 2006,). It is estimated that the world production
of whey is about 104 billion kg per year with the USA producing about 30 billion kg per
year (Saddoud, Hassairi, & Sayadi, 2007; Cheryan, 1998). However, about 30 to 47% of
the total amount of whey available worldwide is not being used (Hutchinson, Balagtas,
Krochta, & Sumner, 2003; Saddoud et al., 2007). Using whey is difficult because it has
low solid content (Bhattacharjee et al., 2006; Cheryan, 1998) while its high biological
oxygen demand (around 32,000 to 60,000 ppm) creates a severe disposal problem
(Cheryan, 1998). Because whey has to be treated before being released into the
environment, this adds an extra burden on waste treatment plants and requires the cheese
industry to build additional treatment facilities (Tuchenhagen South Africa, Ltd., n.d.).
Thus, there is a push to decrease the amount of whey that has to be disposed of by
increasing its utilization.
Whey protein consists of a number of individual protein components. The two
most abundant proteins are β-lac (50-55%) and α-lac (20-25%). β-Lac has a molar mass
of 18.3 kDa and diameter of about 2 nm. The isoelectric point is 5.1 and the denaturation
temperature is 78 °C (Sagis, Ganzevles, Ramaekers, Bolder, & van der Linden, 2002). βLac is largely responsible for solubility, gelation, foaming, emulsification, and flavor
binding of whey protein. Because β-lac is the most abundant protein in whey, it has been
suggested to be one of the main determinants of the properties of whey protein gels (Van
Vliet et al., 2004).
Gelation of Whey Protein
As mentioned before, whey protein coatings act as oil barriers by forming a gel
coating around the food. The characteristic of the gel that is formed determines the ability
of the whey protein film to reduce the oil uptake of fried foods. Gelation of whey protein
gels can be affected by numerous factors such as temperature, concentration of protein,
pH, and ionic strength (Belitz & Grosch, 1999). Gelation of whey proteins is the result of
an aggregation process that occurs through adhesion of exposed hydrophobic regions to
form aggregates that are then stabilized, at least above a certain temperature threshold, by
intermolecular disulfide exchange (Renard & Lefévre, 1992). β-Lac forms gels when the
protein is dissolved in an aqueous solution and heated above the denaturation
temperature. The formation of intermediate aggregates by β-lac involves two broad types
of bonding: Covalent and noncovalent bonding (Galani & Apenten, 1999). β-Lac
contains two disulfide bridges and a free thiol or sulfhydryl group (-SH group). At room
temperature, β-lac exists mostly as a dimer although it may dissociate into monomers at
higher temperatures (Hoffmann & van Mill, 1997). The polymerization reaction leading
to gelation of β-lac is initiated by the dissociation of the dimers through heating.
According to Iametti, de Gregori, Vecchio, and Bonomi (1996), the protein unfolds,
resulting in a molten-globule-like structure, with increased exposure of the previously
buried inner hydrophobic groups and the thiol group. Hydrophobic interactions between
the exposed groups can cause aggregation of the protein molecules while still in the
molten-globule state. The thiol group in the modified monomer is capable of building
oligomers by disulfide bond switch with one of the two disulfide bridges in β-lac, leading
to the formation of disulfide-linked aggregates (Bauer, Carotta, Rischel, & Øgendal,
2000; Iametti et al., 1996). The exposed -SH group initiates sulfhydryl/disulfide (SH/S-S)
interchange reactions, leading to irreversible aggregation/polymerization (Galani &
Apenten, 1999). It is generally accepted that these thiol/disulfide exchange reactions,
leading to the formation of intermolecular disulfide bonds, play a role in the heat-induced
aggregation and gelation of β-lac
(Hoffmann & van Mill, 1997).
Apart from the disulfide cross-linked aggregates, noncovalently driven
association occurs within the aggregates (Galani & Apenten, 1999). These noncovalent
interactions include hydrophobic, ionic, and hydrogen bonding and other weak
interactions that also contribute to the formation of aggregates and a gel network
(Hoffmann & van Mill, 1997). Furthermore, these noncovalent bonds are believed to be
responsible for aggregate formation (Bauer et al., 2000; Manderson, Hardmann, &
Creamer, 1998). The relative contribution of noncovalent interactions to the overall β-lac
aggregation mechanism varies with initial protein concentration, temperature, and pH
(Galani & Apenten, 1999; Verheul & Roefs, 1998).
Effect of pH on whey protein gelation and oil uptake. The reactivity of the free
thiol, exposed after denaturation, has attracted a number of experiments over the years
(Raso, et al., 2005). The reactivity is pH dependent, being unreactive at low pH but
becoming much more reactive at pH levels that are above the isoelectric point (Sawyer &
Kontopidis, 2000; Verheul & Roefs, 1998). At low pH, the thiol groups are buried in the
β-lac dimers, presumably in the region of contact between the monomer subunits
(Hoffmann & van Mill, 1997). Due to the limited exposure of the reactive thiol group,
aggregation and gelation is more dependent on protein concentration, ionic strength, and
heating temperatures at low pH levels compared to those above the isoelectric point
(Schokker et al., 2000). On the other hand, at higher pH, the protein unfolds, exposing the
thiol group and thus increasing its reactivity. A large number of dimers, trimers, and
tetramers appear due to the increase in the number of reactive intermediates with an
exposed, reactive thiol group. This leads to the increased probability of termination of
reactive sulfhydryl groups resulting in the formation of smaller disulfide-linked β-lac
aggregates without a reactive thiol group (Roefs & de Kruif, 1994; Verheul & Roefs,
1998). The large aggregates observed at pH slightly higher than the isoelectric point may
be formed by secondary, noncovalent interactions of primary, disulfide-linked aggregates
(Hoffmann & van Mill, 1997). In their study on the microstructure of gels formed by βlac, Boye, Ma, Ismail, Harwalkar, and Kalab (1997) observed that the compact protein
globules formed at acidic pH of 3 and 5 were either loosely aggregated or fused into
chains or clusters of several globules. Aggregation of protein into these structures
affected the initially uniform distribution of proteins and created large voids that were
filled with the liquid phase of the gel. Gels produced under neutral (pH 7.0) and alkaline
(pH 8.6) conditions had microstructural features completely different from those of the
gels made under acidic conditions; the proteins were more evenly distributed in these gels
than in the gels made at lower pH. Since their clusters were connected through narrow
bridges, void spaces between the clusters were considerably smaller in these gels than in
the acidic gels. A summary of the effects of pH on whey protein gel characteristics based
on studies found in the literature is shown in Table 3.
Table 3 (continued on page 53)
Effects of pH Level Variations on Whey Protein Gelation
pH level
Effect on whey protein gelation
References
pH 2
• No aggregates were formed when the protein
dispersion was left unheated
• Upon heating, rod-like structures formed
• The rods were thought to occur when disulfide
exchange was inhibited by repulsive electrostatic
interactions
Kavanagh, Clark,
and RossMurphy (2000)
pH 2.5
• Mixture of short and long linear aggregates was
formed.
Kavanagh et al.
(2000)
pH 3
• Loosely aggregated or fused into chains or clusters of
several globules
• Large spaces void of proteins which were filled with
the liquid phase of the gel
• Aggregates formed at pH 3 are smaller than that of pH
5
• β-lac was shown to form octamers
Boye et al.
(1997)
pH 4
• Coarse aggregates were uniformly distributed in ‘fine-
Kavanagh et al.
stranded’ network
• β-lac was shown to form octamers
(2000)
pH 4.5
• Coarse, uneven aggregates are formed
• β-lac was shown to form octamers
Kavanagh et al.
(2000)
pH 5
• Loosely aggregated or fused into chains or clusters of
several globules
• Large spaces void of proteins filled with the liquid
phase of the gel
• Aggregates formed at pH 5 are larger than that of pH 3
Boye et al.
(1997)
pH 7
• Proteins were more evenly distributed than in the gels
made at lower pH.
• Void spaces were considerably smaller in these gels
than in the acidic gels.
• Have better water holding capacity than the acidic
gels.
• Aggregates formed were in the nanometer region
(aggregates formed at pH 3-5 are in micrometer)
Boye et al.
(1997)
pH 8-8.6
• Proteins were more evenly distributed in these gels
than in the gels made at lower pH.
• Void spaces were considerably smaller in these gels
than in the acidic gels.
• Have better water holding capacity than the acidic
gels.
• The aggregates formed were in the nanometer region
(aggregates formed at pH 3-5 are in micrometer)
• Aggregates formed at pH 8 are purely made up of
thiol/disulfide bonds
• Thiol reactivity at pH 8 was reported to be as high as
90% and reacts even at room temperature. Some thiol
groups have disappeared via oxidation and
thiol/disulfide exchange reactions and are involved in
intermolecular disulfide bonds
Boye et al.
(1997)
Hoffmann and
van Mill (1997)
Note. β-lac = β-lactoglobulin.
Effect of concentration on whey protein gelation and oil uptake. Because it is
believed that inhibition of oil absorption in fried food is dependent on gel formation of
whey protein isolates, the understanding of the dependence of gel structure on the initial
protein concentration of the coating is crucial in developing this coating. All proteins gel
above a minimum concentration known as the critical gelation concentration (Kavanagh
et al., 2000; Mleko, 1999; Renard & Lefévre, 1992; Vardhanabhuti & Foegeding, 1999).
Preparation of whey protein isolate coatings should be done at or above the critical
gelation concentration to ensure the formation of gels. According to a study done by
Renard and Lefévre (1992), the critical gelation concentration remains at around 1%
(w/w) irrespective of ionic strength at the isoelectric point of β-lac (pH 5.1). The value
increases the more the pH is displaced from the isoelectric point of the protein. At
extreme pH values of pH 2 and 9, Renard and Lefévre (1992) found that the critical
concentration was as high as 8% (w/w). Similar results were found by Kavanagh et al.
who observed that the critical concentration was as low as 1% between pH 4.5 and 5.6
and the critical concentration increased to 5% at lower pH values of 2.3 and 3 and
increased further to 10% when the pH was 7. In a study done by Mleko (1999), it was
shown that the increase in protein concentration that was heated up to produce a heat-set
gel led to a rise in the gel permeability coefficient. This increase suggests that a higher
protein concentration increased the size of the aggregates which formed a gel matrix with
a larger pore size. Ju and Kilara (1998) observed that increasing whey protein
concentration (1–9%) increased the size and amount of the aggregates and resulted in
whey protein polymers that are larger and/or have more asymmetrical shapes
(Vardhanabhuti & Foegeding, 1999). In short, higher protein concentration not only
increased the size and number of the aggregates formed but also increased the pore size
of the gel (Verheul & Roefs, 1998), thereby affecting the gel characteristics of the whey
protein coating and determining its effectiveness as a lipid barrier.
Sensory Evaluation of Foods
The main role of sensory analysis is to obtain information on the sensory
characteristics of the product. In the development of new food products, this process is
important because it affects the decisions involved in materialization of the final product
and its success. Up to 80-90% of new food products fail within a year of production,
resulting in an estimated loss of up to 20 billion dollars. Much of it is due to a flawed
process of product development which includes lack of sensory analysis (Moskowitz,
Beckley, & Resurreccion, 2006). Sensory testing of foods can be grouped into two
general categories: The first category measures sensory responses to the product and
these include discrimination, acceptance, and preference testing; the second category
focuses on characterizing the product by using descriptive analysis testing which may be
accompanied by physicochemical measurements or objective measurements of identified
attributes (Moskowitz et al., 2006). Consumer testing, which looks at the consumer
acceptance of the product, may or may not employ untrained panelists. For example,
acceptance tests would employ consumers of the particular product while discrimination
testing includes both users and nonusers of the product (Stone & Sidel, 1985). Either
way, these tests require a large number of participants, which may range from 25 to 100
or more (Moskowitz et al., 2006; Stone & Sidel, 1985). On the other hand, descriptive
sensory analysis involves rigorous training of a smaller panel of about 10 to 12 selected
consumers (Stone & Sidel, 1985). The panel is trained to generate a lexicon or list of
attributes that are important characteristics of the product, and is required to evaluate
these attributes with an analytical and objective approach (Moskowitz et al., 2006).
Objective or physicochemical analyses rely on analytical measurements of
components that are believed to make up the sensory characteristics. For example, one
method of characterizing color is by using the CIELAB system where three components
of color are used as specified by the Commission Internationale d'Eclairage (CIE) or
International Commission of Illumination. This model is based on the color perception of
92% of the population that does not have vision deficiencies (Hutchings, 1999;
Hutchings, Luo, & Ji, 2002). The whiteness or blackness is represented by L*, redness is
represented by +a*, greenness is represented by –a*, yellowness by +b*, and blueness by
–b* (Jones, 1943) as shown in Figure 2. As for crunchiness, many methods have been
suggested to measure and characterize this property. These include a combination of
mechanical and acoustic measurements (Vickers, 1987), acoustical and force-deformation
measurements, and employment of ultrasonic techniques (Antonova, Mallikarjunan, &
Duncan, 2003).
Figure 2. The CIELAB color space representing the three color coordinates L*, a*, and
b*.
________________________________________________________________________
Note. From Konica Minolta Sensing USA. (2005, June 27). Precise Color
Communications. In Educational Booklet on Color Communication (p. 19). Retrieved
May 12, 2008, from
http://se.konicaminolta.us/support/product_applications/pdf/colorcommunications_app.p
df. Reprinted with permission.
Conclusion
Oil absorption in deep-fat frying is a complex process that involves various factors
related to the food, such as composition and surface characteristics, and factors related to
the frying process such as frying medium, temperature, time, and postfrying handling.
The oil taken up by battered and breaded fried foods during immersion frying can occur
during the frying process via water replacement or immediately after frying due to the
cooling phase effect. Throughout the process, the degree of oil absorption is affected by
the continuous degradation of the frying oil, as described by the surfactant theory. A
variety of ingredients have been employed that retard oil absorption to varying degrees
during immersion frying of battered and breaded fried foods. The majority of these
ingredients are film-forming or aqueous solutions of proteins or nonprotein hydrocolloids
that are either added to the batter or breading, or applied as a postbreading dip.
Whey protein is a potential gel-forming ingredient that can be used as a lipid barrier
in fried foods. It is composed of various proteins, the main protein of which is β-lac, a
globular protein with an isoelectric point of 5.1. This protein makes up 50-55% of the
total protein contained in whey. Other important globular proteins of whey are α-lac and
BSA. All of these proteins, particularly β-lac, can form thermally-induced gels that alter
the porosity of the product, thus lowering both moisture loss due to evaporation and
subsequent oil absorption into the fried food when used as a coating (Dogan et al., 2005,
Van Vliet et al., 2004). The usage of whey protein as food coatings has long been
investigated and applied (Gennadios et al., 1997, Mellema 2003). However, the extent of
commercial application of whey protein coatings as oil barriers has been limited to
separating oil-rich products, such as nuts, from other components of heterogeneous foods
such as cereal (Haines, 2004).
The use of WPI to reduce oil absorption in fried foods, not as a film that requires a
setting time before frying but rather as a postbreading dip after which the product can be
immediately fried, requires optimization of various factors such as pH level and WPI
concentration. In addition, the final product should be nutritious and appealing to the
senses. Since temperature, concentration of protein, pH and ionic strength have a
significant effect on the gelation of whey protein (Belitz & Grosch, 1999), it would be
beneficial to study the effects of these factors on the ability of whey protein isolate
coatings to reduce fat uptake in fried foods. From an industrial standpoint, the whey
protein isolate coating must produce at least a 25% fat reduction compared to the original
reference to meet the labeling criteria for reduced-fat. In addition, the product has to be
deemed acceptable by consumers and this involves the challenge or retaining the
appearance, texture, and flavor of the product.
CHAPTER 3: METHODOLOGY
Overview of Approach
Samples were prepared using the standard commercial breading procedure and
treated with whey protein isolate (WPI) solutions of different concentrations and pH
levels. A 3 x 4 x 2 full factorial design was constructed with three factors, pH level (2, 3,
8), whey protein solution concentration (0%, 2.5%, 5%, 10%), and breading
(crackermeal, Japanese breadcrumb). The complete design was replicated three times.
All samples were then tested for lipid content, moisture content, and texture attributes.
Finally,a descriptive sensory analysis was conducted on the samples. The lipid and
moisture content of the samples determined the effectiveness of the WPI coating in
reducing oil uptake and the effect on moisture content. Instrumental texture analyses
were used in relation to the sensory analysis to determine the effect of the treatment on
appearance, texture, mouth feel, and flavor. The results were then analyzed using analysis
of variance and/or covariance and post hoc means separation was achieved using
Duncan’s multiple range test. Pearson correlation analysis was performed wherever
necessary. A flowchart of the methodology is shown in Figure 3 and the timeline of this
study is shown in Table 4.
This research was funded by the National Dairy Council Discovery Pilot Program,
and the proposal that was approved by the National Dairy Council was written based on a
previous study that looked at the efficacy of WPI, soy protein, and egg albumin as a
postbreading dip in reducing oil absorption in battered and breaded fried chicken patties
(Brannan & Teyke, 2006). It was observed that 10% WPI solutions made at pH 6.1, 5,
and 3, reduced oil absorption by 20.8%, 1.6%, and 68.4%, respectively. The current study
looked at the efficacy of WPI when used at a lower pH level (i.e., pH 2) and at a higher
pH level (i.e., pH 8) compared to the pH levels in the previous study. Treatment was
repeated at pH 3 since it showed the highest lipid reduction in the previous study
(Brannan & Teyke, 2006). In addition, the effect of WPI concentration variations which
was not examined in the previous study was investigated here. Again, WPI at 10%
concentration was repeated in the current study because it was observed to produce lipid
reduction in the previous study.
62
Whey protein
Mixing
Whey protein solution
Three pH levels (pH 2, 3, 8)
Four WPI concentration (0%, 2.5%, 5%, 10%)
Crackermeal
or Japanese
breadcrumbs
Deionized water
48.75% flour
Lipid analysis
Weighing
1% xanthan gum
Mixing
Battering
1% baking powder
Weighing
0.5% salt
Chicken
Frying oil
Grinding
Forming
Moisture analysis
Dipping
48.75% corn flour
Breading
Weighing
Holding
20 g 2-in
≤ 24 hrs at diameter patties 18°C
Deep-frying
At 191°C to
Weighing internal T of
74°C
Weighing
Oil
degradation
measuring
Texture analysis
Color analysis
Sensory analysis
Figure 3. Flowchart of methodology for optimization of whey protein isolate (WPI) solution in reducing oil absorption in batter and
breaded fried chicken when used as a postbreading dip.
Table 4
Timeline for Thesis
Feb Mar Apr May Jun July Aug Sept Oct Nov Dec Jan Feb Mar Apr May
Sample
preparation
Lipid and
moisture
analysis
Instrumental
texture and
color analysis
Sensory
recruitment and
training
Sensory
sampling
Data analysis
Thesis proposal
defense
Thesis defense
Data Collection and Analysis
Materials
All chemicals used in the objective analyses, which included chloroform, methanol, and
sodium chloride, were obtained from Thermo/Fisher (Waltham, MA). Food ingredients
such as chicken breast, batter ingredients, distilled water, and sensory references during
training and sampling were purchased from local retailers. Japanese breadcrumbs,
crackermeal, and frying oil were purchased from Foodservicedirect Inc. (Hampton, VA).
WPI was given by Volac International Ltd. (Orwell, UK) and sodium bisulfate (pHase®)
was given by Jones-Hamilton Co. (Walbridge, OH).
Preparation of Deep Fried Samples
Fresh chicken breast was washed and cut into approximately 4 cm cubes after all
visible fat was removed. The meat was then ground once using a stand mixer with a food
grinder attachment with coarse grinding plate (model K45SS/250W, KitchenAid®,
Whirpool Corporation, MI). The ground chicken was formed into 2-in diameter patties
using a mold and each patty weighed approximately 20 ± 2 g. Due to the large number of
patties needed for this study, patties were stored frozen (-18 °C) for up to 24 hrs before
being coated.
The standard batter formulation was based on the work of Sahin et al. (2005) and
consisted of 48.75% (w/w) wheat flour, 48.75% corn flour, 1.0% xanthan gum, 1.0% salt,
0.5% baking powder and deionized water. The ratio of dry ingredients to water is
adjusted to a viscosity of 3062.5 centipoise (cps). The batter was made fresh on the day it
was used and stored refrigerated (4 °C). WPI solutions (0%, 2.5%, 5%, and 10%) were
prepared by mixing WPI with distilled water. The pH of the solution (pH 2, 3, and 8) was
adjusted using a low flavor impact, food grade acidulant (sodium bisulfate) or baking
soda (sodium bicarbonate). All solutions were prepared 24 hrs in advance, stored
refrigerated (4 °C), and allowed to come to room temperature before use. Patties (in
groups of four or five) were weighed and dipped into batter with the excess shaken off
and weighed again before being coated with breading and weighed. Treated patties were
dipped in WPI solution, weighed, and immediately fried in 191 °C frying oil (canola oil
with added dimethylpolysiloxane) in a deep fryer (Presto® Dual ProFryTM/1800W,
National Presto Industries Inc., WI) until an internal temperature of 74 °C was achieved.
Control patties were not dipped in WPI solution and were directly placed in the frying oil.
After frying, all patties were weighed again and allowed to cool to room temperature for
30 mins before being placed in labeled freezer bags. They were then stored frozen (-18
°C) until analyzed.
Objective Analysis
Oil degradation. Total polar material (TPM) in the frying oil was monitored
throughout the process. An oil sample was taken from the deep fryer before and after
frying of each treatment (12-15 patties per fryer). The samples (1 ml) were microfiltered
(0.45 μm) and equilibrated to 60 °C before the absorbance (ABS) at 490 nm was read.
TPM was calculated using Equation 2 (Xu, 2000):
TPM = -2.7865(ABS)2 + 23.782(ABS) + 1.0309
(2)
Lipid analysis. Analysis on the lipid content of deep-fried samples was
accomplished according to a modified Folch method (Folch, Lees, & Sloane Stanley,
1957). A sample was selected randomly from a treatment and finely ground using a food
processor (Osterizer ®, Jarden Corporation, Boca Raton, FL) until a homogeneous
mixture of coating and chicken was obtained. Lipid from the sample (1 g) was extracted
with three successive washings of chloroform: methanol (2:1 v/v) at 10, 5 and 5 ml
respectively. A volume of 7.5 ml 0.5% NaCl solution was added to assist in separation of
the aqueous layer. The supernatant was removed and evaporated to dryness and the
purified lipid was measured to calculate the final lipid content. The final lipid content
(wet basis) was calculated using Equation 3:
lipid content (%) =
purified lipid weight (g)
× 100%
initial sample weight (g)
(3)
Lipid extractions were duplicated for each patty and a total of three patties were analyzed
from each treatment, including the control (n = 6). This procedure was repeated for each
of the different breading systems (Japanese breadcrumbs and crackermeal).
Moisture analysis. Moisture of deep fried samples was determined by oven
drying. Finely ground samples were weighed (5 g) into tubes and placed in an incubator
at 80 °C. The weights of the samples were measured once a day until a constant weight
was obtained. The moisture content was calculated using Equation 4:
moisture content (%) =
final sample weight (g) - initial sample weight (g)
× 100%
initial sample weight (g)
(4)
As with lipid analysis, moisture analysis was duplicated for each patty and a total of three
patties were analyzed from each treatment, including the control (n = 6), for both
breading systems.
Texture and color analysis. Penetrometry tests using a Ta-XT2i Texture
Analyzer (Texture Technologies Corp., Scarsdale NY/Stable Micro Systems, Godalming,
Surrey UK) were used to evaluate the texture of the samples. Instrumental texture
measurements were made using a 70-mm knife-blade probe on a solid flat platform at a
crosshead speed of 10 mm/s. The depth of penetration of the probe was set at 10 mm to
ensure that the probe fully penetrated the coating system into the substrate matrix.
Samples were positioned such that only 25 mm (1 in) of the sample measured from the
edge was penetrated by the probe surface. This was to assure that only a single edge of
the crust was penetrated uniformly across samples of different shapes. The Texture
Analyzer was controlled via Texture Expert Software and this package was used to
record data and generate force-determination curves. The textural attributes that were
determined were (a) crust fracture work, (b) crust fracture force, (c) total work, (d)
hardness, and (e) resistance (Brannan, 2008). Duplicate readings were taken from one
patty and a total of five patties were measured for each treatment for each breading
system. The thickness of the coating was determined by using calibrated calipers. Each
sample was cut in half through the vertical axis and the height of the upper crust was
measured at three separate points on the cross-section. The average of the three readings
was taken as the thickness of the crust. The CIE L*, a*, and b* values for color was
measured using a Konica BC-10 (Konica Minolta Sensing Americas Inc., Ramsey, NJ).
Three readings were obtained from three different positions on the surface of the patties
and the average of these readings was taken as the color of the samples. A total of five
patties were evaluated for crust thickness and color for each treatment for each breading
system. All instrumental texture analysis, crust thickness, and color measurements were
performed on samples that were reheated in a 191 °C oven until an internal temperature
of 74 °C was reached.
Sensory Analysis
Descriptive sensory analysis was performed to obtain information on the
appearance, mouthfeel sensation, texture, and flavor of the samples. Approval from the
Ohio University Institutional Review Board was obtained for the use of human subjects
prior to the start of the sensory analysis (see Appendix A). The timeline for all sensory
sessions including informational sessions, training sessions, and sampling sessions is
listed in Appendix B.
Panelist selection and training. Recruitment for the sensory panel was done
through five informational sessions. During these sessions, potential panelists were given
a basic introduction to sensory testing, specifically descriptive sensory testing. They were
then asked to fill in a questionnaire asking about known food allergies, food preferences,
medical conditions related to diet, and availability (see Appendix C). Panelists (n = 6; 3
females, 3 males) were chosen based on their answers on the questionnaire. Once they
were chosen, they were asked to fill in an informed consent form (see Appendix D) as
required by the Institutional Review Board of Ohio University.
Panelist training and subsequent testing of samples followed the SpectrumTM
Method (Meilgaard, Civille, & Carr, 1999). Panelists participated in 17, 50-min training
sessions over the period of six months during which training in identifying and rating
various attributes pertaining to flavor and texture were completed. During the first two
training sessions, panelists were trained to identify and discriminate between the five
basic tastes; sweet, sour, salty, bitter, and umami (see Appendixes E and F). Next,
panelists were introduced to methods of lexicon development (see Appendix G). The next
14 training sessions focused on introducing sensory definitions and techniques for
different texture attributes, including hardness, crispness, and juiciness (see Table 4) in
addition to continued practice in the generation of lexicon and identification of basic
tastes. Panelists were also introduced to standard hardness, crispness, and juiciness scale
(see Appendixes H, I, and J). Instructions and scoresheets used throughout these eight
training sessions can be found in Appendixes K through S.
Six of the training sessions were dedicated to sample lexicon development and
fine-tuning for the samples. The first three sessions focused on introducing the concept of
lexicon development to the panel which included discriminating and defining attributes,
and standardizing techniques to identify them. In the next two sessions involving lexicon
development, the panel was asked to identify attributes related to cooked ground chicken
(see Appendix T) and was introduced to using a 15-cm line scale (see Appendix U).
Finally, the panel was asked to identify attributes that pertained to deep-fried, battered,
and breaded chicken patties. Identification of the preliminary attributes was done based
on commercial fried chicken products (Banquet Chicken Breast Nuggets® and Banquet
Chicken Breast Patties®) and fine-tuning of these attributes was done on chicken patties
that were prepared in a similar manner to the crackermeal undipped controls later utilized
in this study. The final lexicon for the samples is shown in Appendix V.
Following the training sessions, two sessions were used to calibrate the panel
against these sensory attributes for crackermeal-coated patties (CMP). A warm-up
sample, which was a battered and breaded patty (with crackermeal) without WPI solution
was prepared in advance and was used as one of the anchors of the 15-cm line scale for
CMP sensory analysis. Panelists participated in another calibration session for Japanese
breadcrumb-coated patties (JBP) after sampling of CMP and before sampling of JBP.
During this calibration session, the same attributes were used, but panelists were required
to re-anchor the new reference sample which was a battered and breaded patty (with
Japanese breadcrumbs) without WPI solution. After each of the calibration sessions for
CMP and JBP, a scoresheet for sampling was generated for each of the breading systems
and these are shown in Appendix W for CMP and X for JBP.
Evaluation of samples. A total of three sampling sessions were held for CMP and
a total of five sampling sessions were held for JBP. In each sampling session, panelists
were supplied with all the anchored references for each attribute that were marked on the
scoresheets (see Appendix W and X). They were also supplied with sterilized water, a
spit-cup, napkins, and unsalted crackers. Each panelist performed independent
evaluations, rating a total of six samples for the various sensory attributes. Panelists were
seated apart from each other in a room under fluorescent light. At the start of the
sampling session, each panelist was given a warm-up sample which was removed before
the real sampling began. Samples were served to each panelist at random, in paper plates
coded with 3-digit random numbers (see Appendix Y and Z). A 5-min break was given
after the first three samples to minimize fatigue and to allow the experimenter to reheat
the next three samples. All samples were reheated in an oven at 191 °C to an internal
temperature of 74 °C and held at that temperature throughout the sampling session.
Statistical Analysis
Data obtained from the study were analyzed using the Statistical Package for the
Social Sciences program (SPSS, version 14.0. 2005, SPSS Inc., Chicago, IL). For each
replication, means for lipid and moisture content were generated from three patties, with
duplicate measurements performed on each patty (n = 6). Means for color, crust
thickness, and texture data were generated from five patties with duplicate measurements
taken for each patty for texture and averaged to give one value for each patty (n = 5). For
color and crust thickness, three measurements were taken for each patty for color and
crust thickness and averaged to give one value per patty (n = 5). Analysis of variance was
used to analyze differences between treatments and post hoc means separation was
achieved using Duncan’s Multiple Range test. Any suspected covariants were analyzed
for significance using analysis of covariance (ANCOVA). Pearson correlation was also
used wherever necessary. Significant differences were determined at the confidence level
of p < 0.05.
To identify outliers, boxplots for all the measured variables were generated within a
breading system, replication, pH, and WPI concentration using Explore on SPSS (e.g.,
lipid content vs. crackermeal × replication 1 × pH 2 × 10% WPI). Values that are not
located within the top, bottom, or interquartile range were identified as outliers. All
outliers that were identified for lipid and moisture content were removed before further
analysis. Outliers within the sensory and instrumental measurements involving
organoleptic properties (appearance, texture, tastes, and flavors) were removed according
to the discretion of the author, due to the smaller sample size for each variable (n = 6 for
sensory analysis data, n = 10 for instrumental texture data, and n = 5 for instrumental
color data and crust thickness measurement). For further statistical analysis, pairwise
deletion of data was used to handle missing data to minimize the loss of data for each
variable.
CHAPTER 4: RESULTS
Oil Degradation
Degradation of the frying medium throughout the frying process, expressed as
total polar material (TPM), is caused by hydrolytic reactions of triglycerides resulting in
the formation of diglycerides, monoglycerides, free fatty acids, and glycerol (O’Brien,
1998). The degradation of the frying medium as reflected in the changes in TPM
throughout the frying process is shown in Figure 4.
30
Total polar material (%)
25
20
Crackermeal
Japanese breadcrumb
15
Recommended maximum
10
5
140
120
100
80
60
40
20
change
120
100
80
60
40
20
0
0
Number of patties fried
Figure 4. Average total polar material (%) of oil samples during the frying process with
relation to the number of patties fried. The oil is changed once during a frying session as
indicated by change on the x-axis. The recommended maximum for total polar material
(TPM) in the food industry is 24% TPM.
Coating Pickup
The mean values for the weights of the raw patty, batter, breading, and whey
pickup, and pre- and postfrying are listed in Table 5. There were no significant
differences between the measured variables within a breading system. When
measurements were compared between crackermeal-coated patties (CMP) and Japanese
breadcrumb-coated patties (JBP), the breading pickup for JBP was significantly higher (p
< 0.05) compared to those for CMP. However, whey pickup and net loss were not
significantly affected by the difference in breading pickup.
Table 5
Mean Values for Weights for Raw Patty, Coating Pickup, Pre- and Postfrying, and
Weight Difference for Deep-Fried, Battered, and Breaded Chicken Patties
Variable
Patty Batter Breading Whey Total Weight Weight Weight
weight pickup pickup pickup pickup prefrying postfrying difference
(g)
(g)
(g)
(g)
(g)
(g)
(g)
(g)
Japanese breadcrumb-coated patties
pH level
Control
pH 2
pH 3
pH 8
20.9
20.4
20.4
20.3
8.9
8.0
8.5
5.4
5.1
5.5
5.8
5.9
0.0
4.4
4.4
4.4
14.0
17.9
18.6
18.6
34.9
38.4
39.2
35.9
29.8
28.0
28.6
28.8
-5.1
-10.3
-10.5
-7.1
WPI concentration
Control
0%
2.5%
5%
10%
20.9
20.5
20.3
20.4
20.4
8.9
7.5
9.0
8.7
8.0
5.1
5.7
5.7
6.0
5.7
0.0
3.9
4.2
4.3
5.0
14.0
16.7
18.8
19.0
18.7
34.9
37.6
39.1
39.4
39.0
29.8
27.4
28.4
29.6
28.6
-5.1
-10.2
-10.7
-9.8
-10.4
Crackermeal-coated patties
pH level
Control
pH 2
pH 3
pH 8
20.1
20.5
20.6
20.5
8.0
7.8
8.0
8.1
3.4
1.8
2.1
2.7
0.0
3.9
3.7
3.3
10.2
13.1
13.6
13.8
31.4
34.0
34.4
34.6
26.2
26.8
27.0
27.8
-5.2
-7.2
-7.4
-6.8
WPI concentration
Control
0%
2.5%
5%
10%
20.1
20.6
20.2
20.9
20.2
8.0
7.9
7.9
7.9
8.2
3.4
1.3
3.3
2.0
2.4
0.0
3.4
3.1
3.8
4.1
10.2
11.9
13.7
13.4
14.7
31.4
33.2
34.5
34.6
34.9
26.2
26.0
27.2
27.7
28.1
-5.2
-7.2
-7.3
-6.9
-6.8
Note. Control indicates patties that are not dipped in WPI solution.
Lipid and Moisture Content
The results of the univariate analysis of the main effects (pH level, WPI
concentration) on lipid content of both CMP and JBP are shown in Table 6. The final
lipid content for both CMP and JBP were significantly affected by the pH level of the
post-breading dips in the order of control > pH 8 > pH 2 = pH 3 for CMP and control =
pH 8 > pH 2 = pH 3 for JBP. For CMP, lipid reduction ranged from 11.4% for pH 8 to
24.3% for pH 3 while JBP lipid reduction ranged from 12.4% for pH 8 to 12.8% for pH
2. In both breading systems, there were no significant differences between patties treated
with WPI dips at pH 2 and pH 3.
The WPI concentration of the post breading dip also significantly affected final
lipid level for both CMP and JBP (see Table 6). Overall, the 10% WPI solution resulted
in patties with significantly lower lipid levels than undipped control patties. However,
WPI concentration affected the two breading systems differently. All CMP exhibited
significantly lower lipid levels than the control, with the lowest lipid content observed for
patties treated at 5% and 10% WPI (21.4% and 24.3% reduction, respectively). Patties
treated with 0% and 2.5% WPI solution also showed significantly lower final lipid
content compared to the control. On the other hand, only JBP patties treated with 10%
WPI showed a significant lipid reduction (16.8%) compared to the control.
Table 6
Main Effect Analysis for Lipid Content (%) for Deep-Fried, Battered, and Breaded
Chicken Patties
Crackermeal-coated patties
Japanese breadcrumb-coated
(CMP)
patties (JBP)
Variable
Lipid content
± s.d.
Lipid content
± s.d.
Control2
13.32a
0.68
14.80a
0.73
pH 2
10.39b
0.39
12.90b
0.65
pH 3
9.78b
0.28
12.95b
0.39
pH 8
13.18a
0.31
14.41a
0.34
Control2
13.32a
0.68
14.79a
0.73
0%
11.46b
0.40
14.42a
0.56
2.5 %
11.56b
0.36
13.62ab
0.39
5%
11.17b
0.37
13.21ab
0.65
10 %
10.26c
0.41
12.30b
0.61
pH level1
WPI concentration3
Note. CMP = crackermeal-coated patties, JBP = Japanese breadcrumb-coated patties. ±
s.d. = standard deviation. Control indicates patties that are not dipped in WPI solution.
Different letters indicate significant differences at p < 0.05 within a breading system and
pH or WPI concentration variation for a particular measured variable. 1n = 72 for each
group. 2n = 16. 3n = 54 for each group.
The results of the two-way univariate analysis for lipid content for CMP and JBP
are shown in Figures 5 and 6, respectively. The highest lipid reduction was observed for
CMP treated with 5% and 10% WPI at pH 2 and at 10% WPI at pH 3. For JBP, the
highest lipid reduction was seen in JBP treated with 10% WPI at pH 3 and pH 2. In both
breading systems, patties treated at pH 8 with 2.5%, 5%, and 10% WPI were not
significantly different compared to the control. While the results for CMP at pH 3 across
all WPI concentrations showed significantly lower lipid content compared to the control,
the results for JBP were less consistent since only JBP treated with 10% WPI at pH 3 was
significantly lower compared to the control.
15
14
0% WPI
2.5% WPI
5% WPI
10% WPI
a
ab
Lipid content (%)
abcd
abc
abcd
13
bcde
12
11
e
cde
cde
de
e
e
10
cde
9
8
7
control
pH 2
pH 3
pH 8
Figure 5. Final lipid content (%) for crackermeal-coated patties (CMP) treated at various
pH levels and whey protein isolate (WPI) concentrations. Control indicates patties that
are not dipped in WPI solution. Different letters indicate significant differences at p <
0.05 within a treatment (pH x WPI concentration). ncontrol = 16. ntreatment = 18 for each
group.
17
0% WPI
15
Lipid content (%)
abc
2.5% WPI
10% WPI
a
ab
bc
bc
bcd
cd
cd
13
5% WPI
abcab
c
cd
d
11
d
9
7
5
control
pH 2
pH 3
pH 8
Figure 6. Final lipid content (%) for Japanese breadcrumb-coated patties (JBP) treated at
various pH levels and whey protein isolate (WPI) concentrations. Control indicates
patties that are not dipped in WPI solution. Different letters indicate significant
differences at p < 0.05 within a treatment (pH x WPI concentration). ncontrol = 16. ntreatment
= 18 for each group.
When univariate analysis was performed on final moisture content of both CMP
and JBP, only CMP were observed to be significantly affected by pH level and WPI
concentration (p < 0.05). Results for the analysis on the main effects for CMP are shown
in Table 7. The results for affect of pH level on final moisture content mimics that
observed with final lipid content. CMP treated at pH 8 was not significantly different
compared to the control. However, CMP treated at pH 2 and 3 had significantly lower
moisture content ranging from 42.59% to 43.10% when compared to the control. For the
effect of WPI concentration, CMP treated with all levels of concentration (0%, 2.5%, 5%,
and 10% WPI) showed significantly different moisture content compared to the control
with CMP at 5% WPI having the highest moisture reduction of 8.46%.
Table 7
Main Effect Analysis for Moisture Content (%) for Deep-Fried, Battered, and Breaded
Chicken Patties
Variable
Crackermeal-coated patties
Japanese breadcrumb-coated
(CMP)
patties (JBP)
Moisture content
± s.d.
Moisture content
± s.d.
Control2
46.51a
0.94
51.34
0.47
pH 2
43.10b
0.37
49.82
0.57
pH 3
42.59b
0.48
50.31
0.42
pH 8
45.37a
0.31
51.24
0.50
Control2
46.51a
0.94
51.34
0.47
0%
44.28b
0.28
50.78
0.77
2.5 %
44.50b
0.45
50.43
0.40
5%
42.57c
0.61
50.01
0.47
10 %
43.26bc
0.43
50.56
0.61
pH level1
WPI concentration3
Note. ± s.d. = standard deviation. Control indicates patties that are not dipped in WPI
solution. Different letters indicate significant differences at p < 0.05 within a breading
system and pH or WPI concentration variation for a particular measured variable. 1n = 72
for each group. 2n = 16. 3n = 54 for each group.
The results for the two-way univariate analysis for CMP and JBP for moisture
content are shown in Figures 7 and 8, respectively. As mentioned earlier, while there
were no significant differences observed for the main effects for moisture content for
JBP, the interaction between pH level and WPI concentration showed significant
differences. The highest moisture reduction for JBP was observed for patties treated with
2.5% WPI at pH 2. This treatment was the only treatment for JBP that was significantly
different compared to the control. For CMP, the lowest moisture content was observed at
pH 3 and 5% WPI.
53
Moisture content (%)
51
0% WPI
2.5% WPI
5% WPI
10% WPI
a
49
ab
bcd
47
cd
def
ef
45
bcd
cdef
cde
cdef
f
abc
cd
e
43
41
39
37
35
control
pH 2
pH 3
pH 8
Figure 7. Final moisture content (%) for crackermeal-coated patties (CMP) treated at
various pH levels and whey protein isolate (WPI) concentrations. Control indicates
patties that are not dipped in WPI solution. Different letters indicate significant
differences at p < 0.05 within a treatment (pH x WPI concentration). ncontrol = 16. ntreatment
= 18 for each group.
55
0% WPI
2.5% WPI
53
abc
ab
Moisture content (%)
ab
abc
51
5% WPI
10% WPI
ab a
ab
ab
abc
bc
a
ab
c
c
49
47
45
43
control
pH 2
pH 3
pH 8
Figure 8. Final moisture content (%) for Japanese breadcrumb-coated patties treated at
various pH levels and whey protein isolate (WPI) concentrations. Control indicates
patties that are not dipped in WPI solution. Different letters indicate significant
differences at p < 0.05 within a treatment (pH x WPI concentration). ncontrol = 16. ntreatment
= 18 for each group.
Surface Appearance
There was an obvious difference in appearance between patties treated with WPI
dips at pH 8 compared to the control and those at pH 2 and pH 3. The samples treated
with WPI at pH 8, regardless of WPI concentration, looked burned and unappealing. As
shown in Table 8, lightness (L*) and both chromaticity coordinates (a*, b*) were
significantly different for pH 8 than for the other samples. For JBP, L*, a*, and b* were
all lower for pH 8 than in the control or at pH 2 or 3. In CMP, L* and b* were lower
while a* was higher for pH 8 than in the control or at pH 2 or 3.
Panelists rated the appearance of the patties for color, evenness of color, and
surface greasiness on an anchored 15-cm line scale (see Table 8) for patties treated across
all WPI concentrations at pH 2 and 3. As shown in Table 8, no significant differences
were observed for any of these attributes between patties treated at pH 2 and 3 and with
the undipped control. However, instrumental color analysis showed that JBP patties
treated with WPI at pH 2 were slightly but significantly darker compared to the control
patties. This effect was not observed for patties treated with WPI at pH 3. No differences
were observed between the control and patties treated with WPI at pH 2 or pH 3 for
either of the chromaticity coordinates. In CMP, patties treated with WPI at pH 2 and 3
were significantly lighter (L*) and exhibited a significantly lower a* value than the
undipped control. Analysis of b* values shows that patties treated at pH 2 exhibited a
significantly higher b* than the control, while patties treated at pH 3 exhibited a
significantly lower b* than the control. These results suggest that pH has more of an
effect on CMP than on JBP.
86
Table 8 (continues on pages 87-88)
Mean Values for Sensory Color, Evenness of Color, and Greasiness of Surface Rating and Instrumental Color Values for Deep-Fried,
Battered, and Breaded Chicken Patties
Sensory
Variable
Evenness
Color
± s.d.
Instrumental
Greasiness
± s.d.
of color
± s.d.
L*
± s.d.
a*
± s.d.
b*
± s.d.
of surface
Crackermeal-coated patties (CMP)
pH level1
Control2
8.7
0.7
8.6
0.7
6.2
0.1
50.9b
1.0
12.7b
0.8
32.6a
0.6
pH 2
6.5
0.3
7.8
0.2
6.3
0.2
54.1a
0.6
9.6c
0.4
57.9c
0.6
pH 3
6.8
0.3
8.7
0.3
6.1
0.1
53.7a
0.6
9.6c
0.4
29.8b
0.6
pH 8
-
-
-
-
-
-
37.1c
1.5
13.9a
0.4
24.2d
0.7
87
WPI concentration3
Control2
8.5a
0.7
8.6
0.7
6.2
0.1
50.9b
1.0
12.7ab
0.8
32.6a
0.6
0%
5.2c
0.3
8.2
0.3
6.5
0.1
56.0a
0.7
7.7c
0.4
27.7bc
0.6
2.5 %
7.1b
0.5
8.0
0.3
6.0
0.2
46.9c
1.6
12.0b
0.5
28.4b
0.7
5%
6.6b
0.4
7.9
0.5
6.4
0.2
45.6cd
1.8
12.3ab
0.5
26.7bc
0.9
10 %
7.5b
0.4
8.9
0.2
6.1
0.2
45.2d
1.7
12.9a
0.5
26.3c
1.1
Japanese breadcrumb-coated patties (JBP)
pH level1
Control2
10.1
0.3
9.4
0.5
6.7
0.2
43.7a
1.1
12.4a
0.7
18.9a
1.7
pH 2
9.8
0.2
8.5
0.2
6.9
0.1
41.8b
1.2
12.0a
0.5
18.4a
0.6
pH 3
9.7
0.3
8.6
0.2
6.8
0.1
42.8ab
1.0
12.7a
0.4
18.9a
0.6
pH 8
-
-
-
-
-
-
35.8c
1.4
9.6b
0.4
11.3b
0.9
88
WPI concentration3
Control2
10.1b
0.3
9.4
0.5
6.7
0.2
43.7b
1.1
12.4a
0.7
18.9b
1.7
0%
8.8c
0.3
8.7
0.2
6.7
0.1
45.2a
1.1
11.6abc
0.5
21.0a
0.7
2.5 %
10.6ab
0.4
8.2
0.3
7.1
0.1
38.7c
1.3
11.9ab
0.5
15.1c
0.9
5%
11.4a
0.4
9.1
0.3
6.9
0.2
37.7c
1.6
11.4bc
0.5
14.6c
1.0
10 %
11.3a
0.3
8.4
0.3
6.7
0.2
38.1c
1.5
10.9c
0.6
14.1c
0.9
Note. * Position on 15-cm line scale. ± s.d. = standard deviation. Control indicates patties that are not dipped in WPI solution.
Different letters indicate significant differences at p < 0.05 within a breading system and pH or WPI concentration variation for a
particular measured variable. For sensory: 1n = 24 for each group. 2n = 6. 3n = 18 for each group. For instrumental: 1n = 20 for each
group. 2n = 5. 3n = 15 for each group.
The concentration of the WPI in the dips did not have an affect on evenness of
color or greasiness of the surface of the patties for either breading system, but did
influence color (see Table 8). In JBP patties, color of the patties was observed as 0% WPI
< control < 2.5% WPI = 5% WPI = 10% WPI. Thus, patties dipped in water at varying
pH levels, i.e. 0% WPI, were more yellow than the control while patties treated with WPI
were darker brown. This trend was reflected in the chromaticity coordinate b*, for which
an increasing positive value indicates a more yellow color. In CMP, the color of the
patties was observed as 0% WPI < 2.5% WPI = 5% WPI = 10% WPI < control. Thus, in
CMP, all dipped patties were less dark brown (more yellow) than the control; however,
the opposite trend was observed for the chromaticity coordinate b*, because all WPI
treated samples were significantly less yellow than the control although all of the WPItreated patties were lighter (L*) than the control.
Texture
The only texture sensory attributes that showed significant differences for main
effect were hardness and crunchiness that were observed when WPI concentrations were
varied for CMP (see Table 9). Hardness was defined as the force required to bite through
a sample (Meilgaard et al., 1999) while crunchiness reflects the amount of sound and
fracturability detected when the sample is chewed once with the molars (Vickers, 1987).
Hardness for CMP was rated in the order of control = 0% = 5% > 2.5% > 10% WPI.
When the results for objective values for hardness were analyzed, it was observed that
CMP in the presence of WPI were significantly harder compared to the control. Results
from the sensory and instrumental measurements of hardness suggest that while
variations in the pH levels of the dip does affect the hardness of the patties, changes in
hardness can only be perceived in the presence of WPI. As for crunchiness, CMP treated
with 10% WPI was rated as having the highest intensity. Patties treated at other WPI
concentrations were not significantly different compared to the control. An instrumental
measurement that may correspond to perceived crunchiness is crust fracture (Brannan,
2008) which represents the peak force at the point of crust thickness. Thus, higher crust
fracture values imply a crunchier product. CMP treated with 2.5%, 5%, and 10% WPI
were observed to have significantly higher crust fracture values compared to the control
(see Table 9). Similar to the results observed with instrumental hardness, CMP treated
with 0% WPI (i.e., water) was not significantly different compared to the control. In
addition to hardness and crust fracture, crust work, which is the work done until the crust
fracture occurs, was also observed to show significant differences. CMP treated at 0%
and 2.5% WPI had significantly lower crust work compared to the control.
91
Table 9 (continued on pages 92-93)
Mean Values for Sensory Hardness and Crunchiness, Crust Thickness, and Instrumental Hardness, Crust Fracture, and Crust Work
for Deep-Fried, Battered, and Breaded Chicken Patties
Sensory
Instrumental
Crust
Hardness
Crunchiness
± s.d.
(cm)
Crust
Total
± s.d. fracture ± s.d.
work
(g)
(g)
Crust
Hardness
± s.d.
thickness ± s.d.
(cm)
± s.d.
work
± s.d.
(g)
(mm)
(g)
Crackermeal-coated patties (CMP)
pH level1
Control2
5.8
0.2
5.8
0.5
3.04b
0.32
651.53
55.00 194.63 24.71 930.51 17.36 59.25 14.91
pH 2
6.2
0.1
6.0
0.3
3.73a
0.12
839.41
28.86 259.98 12.56 397.58 12.10 44.36
2.9
pH 3
6.4
0.1
6.1
0.2
2.92b
0.11
862.80
29.53 247.29 20.01 423.93 14.54 45.32
5.28
pH 8
-
-
-
-
3.16b
0.12
858.04
28.32 264.92 16.38 422.18 14.57 47.91
4.00
92
WPI concentration3
Control2
5.8b
0.2
5.8b
0.5
3.04cd
0.32
651.53c
55.00 194.63b 24.71 930.51 17.36 59.25a 14.91
0%
6.1b
0.1
5.1b
0.2
2.74d
0.12
915.93a
38.34 209.37b 15.63 419.87 15.57 34.37b 4.19
2.50%
6.5a
0.1
6.1b
0.5
3.21bc
0.14 851.08ab 31.66 259.64a 22.12 406.87 15.77 46.82b 5.61
5%
6.0b
0.1
5.6b
0.2
3.49ab
0.13
24.23 267.12a 15.94 396.63 12.34 50.37a
4.52
10%
6.6a
0.1
7.4a
0.3
3.64a
0.15 850.65ab 37.07 291.65a 19.87 436.09 19.33 50.95a
4.26
813.22b
Japanese breadcrumb-coated patties (JBP)
pH level1
Control2
5.6
0.3
7.2
0.5
4.67
0.47
943.08
83.82 423.98 70.85 471.42 10.59 98.61 37.00
pH 2
5.2
0.1
6.7
0.3
4.36
0.24
945.31
26.35 409.93 15.90 477.56 4.23
90.35 14.43
pH 3
5.4
0.1
6.8
0.2
4.05
0.16 1004.06 32.74 404.09 24.81 492.53 4.64
92.09 13.74
pH 8
-
-
-
-
4.24
0.15
87.71
904.00
21.60 386.26 18.11 450.37 3.17
9.80
93
WPI concentration3
Control2
5.6a
0.3
7.2
0.5
4.67
0.47
943.08
83.82 423.98 70.85 471.42 10.59 98.61 37.00
0%
5.0b
0.1
7.1
0.3
4.22
0.32
993.39
28.69 391.08 23.30 493.05 4.44
2.50%
5.4a
0.2
6.9
0.4
4.38
0.19
936.44
39.13 420.30 25.45 473.10 5.96 100.15 8.96
5%
5.2ab
0.2
7.0
0.3
4.13
0.18
932.66
31.69 385.58 24.44 460.23 4.70
87.06
7.70
10%
5.5ab
0.2
6.6
0.3
4.13
0.15
942.00
27.07 403.42 18.54 467.70 3.42
88.50
6.21
84.48
9.81
Note. * Position on 15-cm line scale. ± s.d. = standard deviation. Control indicates patties that are not dipped in WPI solution.
Different letters indicate significant differences at p < 0.05 within a breading system and pH or WPI concentration variation for a
particular measured variable. For sensory: 1n = 24 for each group. 2n = 6. 3n = 18 for each group. For instrumental: 1n = 20 for each
group. 2n = 5. 3n = 15 for each group.
Mouth Feel Sensation and Flavor
The results for the sensory attributes that describe mouth feel sensation and flavor are
shown in Table 10. None of these attributes were observed to be significantly different
compared to the control and between treatments except for bitterness in JBP as WPI
concentration is varied. Panelists rated those treated with 10% WPI to be significantly
more bitter compared to the control.
Table 10
Mean Values for Rating of Mouth Feel Attributes for Deep-Fried, Battered, and Breaded
Chicken Patties
Variable
Moisture release
± s.d.
Oil mouth coating
± s.d.
Crackermeal-coated patties (CMP)
pH level1
Control2
pH 2
pH 3
6.8
6.8
7.4
0.5
0.3
0.3
4.3
4.1
4.1
0.1
0.1
0.1
WPI concentration3
Control2
0%
2.5%
5%
10%
6.8
6.9
7.0
7.9
6.8
0.5
0.3
0.4
0.4
0.4
4.3
4.1
4.1
4.2
4.0
0.1
0.1
0.1
0.1
0.2
Japanese breadcrumb-coated patties (JBP)
pH level1
Control2
pH 2
pH 3
5.0
4.4
4.2
0.3
0.1
0.2
4.1
3.8
3.7
0.2
0.1
0.1
WPI concentration3
Control2
0%
2.5%
5%
10%
5.0
4.4
4.3
4.4
4.2
0.3
0.1
0.2
0.2
0.2
4.1
3.8
3.8
3.8
3.6
0.2
0.1
0.1
0.1
0.1
Note. ± s.d. = standard deviation. Control indicates patties that are not dipped in WPI
solution. Different letters indicate significant differences at p < 0.05 within a breading
system and pH or WPI concentration variation for a particular measured variable. 1n = 24.
2
n = 6. 3n = 18.
Table 11
Mean Values for Rating of Basic Tastes for Deep-Fried, Battered, and Breaded Chicken
Patties
Variable
Salty
±
s.d.
Sweet
±
s.d.
Sour
±
±
Bitter
s.d.
s.d.
Umami
±
s.d.
Crackermeal-coated patties (CMP)
pH level1
Control2
pH 2
pH 3
2.4
2.2
2.3
0.1
0.1
0.1
1.2
1.1
1.1
0.1
0.1
0.1
0.0
0.1
0.1
0.0
0.0
0.0
0.0
0.1
0.1
0.0
0.0
0.0
0.9
0.7
0.9
0.2
0.1
0.1
WPI concentration3
Control2
0%
2.5%
5%
10%
2.4
2.2
2.1
2.5
2.1
0.1
0.1
0.1
0.1
0.1
1.2
1.1
0.9
1.1
1.2
0.1
0.1
0.1
0.1
0.3
0.0
0.1
0.2
0.0
0.1
0.0
0.0
0.1
0.0
0.0
0.0
0.1
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.9
0.8
0.7
1.0
0.8
0.2
0.1
0.1
0.1
0.1
Japanese breadcrumb-coated patties (JBP)
pH level1
Control2
pH 2
pH 3
1.1
1.0
1.3
0.2
0.1
0.2
0.1
0.1
0.1
0.0
0.0
0.0
0.1
0.1
0.1
0.0
0.0
0.0
0.0
0.1
0.1
0.0
0.0
0.0
0.2
0.2
0.2
0.1
0.0
0.0
WPI concentration3
Control2
0%
2.5%
5%
10%
1.1
1.0
1.5
1.1
1.4
0.2
0.1
0.4
0.1
0.3
0.1
0.1
0.1
0.1
0.1
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.1
0.1
0.1
0.0
0.0
0.0
0.0
0.0
0.0b
0.0b
0.1b
0.1ab
0.2a
0.0
0.0
0.0
0.0
0.1
0.2
0.2
0.2
0.1
0.2
0.1
0.1
0.1
0.0
0.0
Note. ± s.d. = standard deviation. Control indicates patties that are not dipped in WPI
solution. Different letters indicate significant differences at p < 0.05 within a breading
system and pH or WPI concentration variation for a particular measured variable. 1n = 24.
2
n = 6. 3n = 18.
Table 12
Mean Values for Rating of Flavor Attributes for Deep-Fried, Battered, and Breaded
Chicken Patties
Variable
Cooking
oil
±
s.d.
Chicken
fat
±
s.d.
Chickeny
±
s.d.
Whey
±
s.d.
Crackermeal-coated patties (CMP)
pH level1
Control2
pH 2
pH 3
2.8
2.5
2.4
0.2
0.1
0.1
3.6
3.6
3.5
0.2
0.1
0.1
5.6
5.2
5.3
0.2
0.1
0.1
1.8
1.5
1.5
0.3
0.2
0.2
WPI concentration3
Control2
0%
2.5%
5%
10%
2.8
2.5
2.3
2.3
2.7
0.2
0.2
0.2
0.1
0.2
3.6
3.7
3.3
3.7
3.4
0.2
0.1
0.1
0.1
0.1
5.6
5.2
5.1
5.2
5.5
0.2
0.1
0.2
0.2
0.2
1.8
1.5
1.6
1.7
1.2
0.3
0.2
0.3
0.2
0.3
Japanese breadcrumb-coated patties (JBP)
pH level1
Control2
pH 2
pH 3
3.8
3.9
4.0
0.3
0.2
0.2
3.7
4.4
3.7
0.2
0.8
0.1
6.3
5.9
6.1
0.3
0.2
0.1
1.4
1.5
1.7
0.3
0.2
0.2
WPI concentration3
Control2
0%
2.5%
5%
10%
3.8
3.9
3.8
4.2
3.7
0.3
0.2
0.2
0.3
0.2
3.7
4.8
3.8
3.7
3.6
0.2
0.9
0.2
0.1
0.1
6.3
6.3
5.8
5.9
5.7
0.3
0.1
0.2
0.1
0.2
1.4
1.3
1.8
1.8
1.6
0.3
0.2
0.3
0.3
0.2
Note. ± s.d. = standard deviation. Control indicates patties that are not dipped in WPI
solution. Different letters indicate significant differences at p < 0.05 within a breading
system and pH or WPI concentration variation for a particular measured variable. 1n = 24.
2
n = 6. 3n = 18.
CHAPTER 5: DISCUSSION AND CONCLUSION
Oil Degradation
The increase in total polar material (TPM) wass expected to increase the oil
absorption of the fried foods due to the surfactant nature of these breakdown materials
(Blumenthal & Stier, 1991). However, despite a maximum TPM measurement of 8% (see
Figure 2), this was not observed to affect oil absorption (data not shown). The TPM that
was generated throughout the frying process might have been be too low to produce any
significant increase in oil absorption since it has been observed that interfacial tension
only decreases once a certain critical level of TPM is generated (Dana & Saguy, 2006).
Furthermore, the maximum TPM observed (8%) was well below 24% maximal level of
TPM for frying oil as recommended by the delegates of the 3rd International Symposium
on Deep-Fat Frying (Deutsche Gesellschaft für Fettwissenschaft, 2000). In short, the
absence of the relation between TPM and oil absorption implies that oil absorption may
be only affected by degradation of the frying medium above a critical level.
Effect of WPI Treatment on Lipid Content
The analysis of the main effects of WPI concentration on lipid content showed
that the lowest final lipid content for CMP and JBP was observed for patties treated with
10% WPI (see Table 6). It is likely that protein concentration affects the lipid barrier
properties by influencing the structure of the protein gel. When the level of protein is too
low, a protein gel is difficult to establish because intermolecular interactions tend to
occur rather than intramolecular interactions (Belitz & Grosch, 1999). As the protein
content increases, the likelihood of intermolecular crosslinks increases and gelation can
occur. The conversion of monomers of β-lac to fibrils and subsequent aggregation
increases with protein concentration (Bolder, Vasbinder, Sagis, & van der Linden, 2007).
However, some studies have shown that gels formed with higher WPI concentrations
have larger aggregates and smaller pores (Mleko, 1999; Verheul & Roefs, 1998), while
others suggest that gel structure is independent of protein concentration (Lefévre &
Subirade, 1999; Le Bon, Nicolai, & Durand, 1999). Our results demonstrated that while
postbreading WPI dips did inhibit oil absorption, especially at 5% and 10% WPI, there
was no difference between the amount of final lipid content between patties treated with
solutions containing 2.5% WPI and those treated with 0% WPI. Because a reduction in
lipid content was observed for CMP at 0% WPI compared to the control, this implied that
the pH of the WPI-containing postbreading dips has a larger influence on the amount of
oil absorbed into fried patties than the WPI concentration of the dips.
The analysis of the main effects of pH level on lipid content showed that the
highest lipid reduction was observed at low pH, such as pH 2 and 3, for both CMP and
JBP (see Table 6). The importance of pH level on the fat reducing properties of the WPI
dips could be inferred from the influence that ionic strength has on protein gelation
(Durand, Gimel, & Nicolai, 2002; Sagis et al., 2002; Schokker et al., 2000). The presence
of charged molecules in a protein solution either enhances or decreases electrostatic
repulsion between protein monomers. At low pH (e.g., pH 2 and 3), aggregates are
formed almost exclusively via noncovalent bonding while at higher pH levels (e.g., pH
7), disulfide interactions between protein molecules are present (Kavanagh et al., 2000).
While increased protein concentration promotes random aggregation due to the close
contact between monomers, this does not matter as much if the monomers repel each
other due to similar charges. Hence, the observed reduction in oil absorption at high
protein concentration (e.g., 10% WPI) may be due to the influence of random aggregation
that, as the protein concentration decreases, increases the role of pH due to its influence
on protein charges (Schokker et al., 2000).
For all WPI concentrations, the lipid contents of patties treated at pH 8 were
mostly higher compared to those at pH 2 and 3 for both breading systems. If the lipid
inhibition observed for WPI dips at low pH is the result of thermally induced gels of one
or more of the whey protein fractions, then gels produced at low pH levels have better
lipid barrier properties compared to those which form at high pH levels. When the
structures of heat-induced globular gels were analyzed, it was observed that gels formed
at lower pH levels consist of large, fibrillar aggregates (Durand et al., 2002, Schokker et
al., 2000). There were also large voids between the chains of globules (Boye et al., 1997).
On the other hand, at pH levels higher than the isoelectric point, the gels consist of
smaller, particulate aggregates that are more evenly distributed and the void spaces are
much smaller compared to those observed at pH levels below the isoelectric point (Boye
et al.; Hoffman & van Mill, 1998). The difference in pore formation of acidic and
alkaline gels may account for the results observed for final lipid content in this study. The
water replacement mechanism of oil uptake suggests that as steam escapes during the
frying process, it forms large voids with low positive vapor pressure through which oil
enters the product (Dana & Saguy, 2006). Acidic gels tend to form larger pores, and thus,
according to the water replacement mechanism, more oil is absorbed during the frying
stage. However, after removal from the frying medium, the smaller pores formed by the
alkaline gels may encourage uptake of oil during cooling since the sudden drop of
positive vapor pressure sucks in oil that is present on the food surface (Dana & Saguy,
2006). Because oil uptake during the cooling phase has been shown to account for the
bulk of the oil absorption in fried foods (Moreira et al., 1997), factors that increase oil
absorption through this mechanism would ultimately increase final oil content of the fried
food. This is observed with the higher final lipid content of patties dipped in WPI
solutions at pH 8 compared to those at pH 2 and 3.
Effect of WPI Treatment on Moisture Content
The analysis on the main effects of WPI concentration and pH levels on final
moisture content indicated that WPI concentration had a different effect on CMP
compared to JBP (see Table 7). The highest reduction in moisture content was for CMP
treated with high WPI concentrations, that is, 5% and 10% WPI, and at low pH levels,
that is, pH 2 and 3, while none of the WPI concentration and pH variations affected
moisture content for JBP. CMP that exhibited the highest moisture reduction coincides
with those that have the highest lipid reduction (see Table 6).
While it has been suggested that high moisture retention would lead to lower oil
reduction (Moreira et al., 1997; Pinthus et al., 1993), the results from both CMP and JBP
suggested that oil uptake was not only affected by the direct exchange between water and
oil, but other factors as well, such as those mentioned previously (see Factors Affecting
Oil Absorption). While the formation of pores through the evaporation of water is
involved in oil uptake, there was no direct relationship between moisture loss and oil
absorption that was observed in this study. This points to the complexity of the dynamics
of moisture and oil migration during the frying process as mentioned by the water
replacement mechanism (Pinthus & Saguy, 1994; Rice & Gamble, 1989) and after
removal from the frying medium via the cooling phase effect (Moreira et al., 1997). In
addition, while moisture loss is continuous throughout the frying process, oil uptake
reaches a maximum level and remains constant until removal of the fried food from the
frying medium (Yamsaengsung & Moreira, 2002). Nevertheless, moisture loss is still
related to oil uptake and factors that affect oil uptake would ultimately play a role in
determining the movement of moisture. Gels that have large pores allow moisture to
vaporize more easily compared to those with smaller pores and hence, gels at lower pH
levels would be expected to show lower moisture content compared to gels at higher pH
levels. This may explain why moisture content was less at low pH levels.
Effect of WPI Treatment on Organoleptic Properties of Fried Chicken Patties
In addition to lowering the fat content in fried foods, product developers must also
ensure that the product is accepted by consumers. In other words, all sensory
characteristics associated with the food such as flavor, color, and texture must be met
(Fuller, 2004). For example, a desirable and expected textural property in fried foods is
crunchiness or crispness. Fried foods that lack this attribute are usually seen as being of
poor quality and will not appeal to the majority of consumers. In addition, consumers
often use color as a quick and often effective parameter in determining the quality of
foods.
Surface Appearance: Color
Surface color is a quick and often effective parameter in determining the quality
of fried foods. As shown in Table 8, lightness (L*) and both chromaticity coordinates (a*,
b*) were significantly different for pH 8 than for the other samples. For JBP, L*, a*, and
b* were all lower for pH 8 than in the control or at pH 2 or 3. In CMP, L* and b* were
lower while a* was higher for pH 8 than in the control or at pH 2 or 3. Fried foods often
exhibit increased values for a* and lower values for L* and b* when they are fried under
nonoptimum conditions such as long frying time, in highly degraded oil, and at very high
temperatures (Krokida et al., 2001; Ngadi et al., 2007). For this reason and because
patties treated with WPI at pH 8 exhibited minimal oil inhibition properties (see Table 6),
patties treated with WPI at pH 8 were not further analyzed by sensory analysis.
As shown in Table 8, no perceivable significant differences were observed for
color, evenness of color, and greasiness of surface between patties treated at pH 2 and 3
and with the undipped control. However, when instrumental measurement of surface
color was performed, it was observed that JBP at pH 2 were significantly darker
compared to the control patties. This effect was not observed for patties treated with WPI
at pH 3. No differences were observed between the control and patties treated with WPI
at pH 2 or pH 3 for either a* or b* values. In CMP, patties treated with WPI at pH 2 and
3 were significantly lighter (higher L* value) and less red (lower a* value) than the
undipped control. A significantly higher b* values for patties treated at pH 2 indicated
that treating CMP at pH 2 produced a more yellow patty while the significantly lower b*
value for CMP treated at pH 3 means that this pH level made the patty less yellow
compared to the control. These results suggest that pH has more of an effect on the color
of CMP than on JBP.
The concentration of the WPI in the dips did not have an effect on evenness of
color or greasiness of the surface of the patties for either breading system, but did
influence color (see Table 8). In JBP patties, color of the patties was rated as 0% WPI <
control = 2.5% WPI = 5% WPI = 10% WPI. Thus, patties dipped in water at varying pH
levels, that is, 0% WPI, were more yellow than the control while patties treated with WPI
were darker brown. This trend was reflected in the chromaticity coordinate b* as only
JBP treated with 0% WPI showed a significantly higher b* value, indicating a more
yellow color compared to the control. In CMP, the color of the patties was rated as 0%
WPI < 2.5% WPI = 5% WPI = 10% WPI < control. Thus in CMP, the presence of WPI
resulted in patties that were less dark brown (more yellow) than the control. However, the
opposite trend was observed for the chromaticity coordinate b*, where JBP across all
WPI concentration had a lower b* value (less yellow) compared to the control. In
addition, L* values were lower for JBP treated with WPI. These results suggest that while
treating the patties with acidic solutions, i.e. pH 2 and 3, made the patty more yellow and
bright, the presence of WPI darkened the color of the patties and downplayed the
“yellowing” and “brightening” effect of low pH levels.
When correlation analysis was done on the sensory color, L*, a*, and b* for
CMP, it was observed that the L* values were negatively correlated with color (r = 0.480, p < 0.01) while a* values were positively correlated to color (r = 0.508, p < 0.01).
Surprisingly, b* values (indicating yellowness) was weakly correlated with color (r =
0.237, p < 0.05). The results of the correlation analysis suggest that the panel relied more
on the lightness and the redness of the patties in rating the color of CMP compared to the
yellowness even though the scale was set to range from yellow to dark brown. On the
other hand, when a similar correlation analysis was done on JBP, none of the
instrumental color values were significantly correlated with color rating of the panel. The
inconsistencies between the results from the univariate and correlation analysis of
perceived color for each breading system imply the complexity of the perception of color
because it is dependent on various other factors such as (a) variations in the food product
such as particle size (crackermeal vs. Japanese breadcrumbs), (b) differences in
concentrations and distributions of light-absorbing pigments (Little, 1973), and (c)
variations in the psychology of the consumers (Churchland, 2007). In foods, colorimetry
is not used for the strict reproduction of the product, but more as an indication of the
range of acceptability of the product as it pertains to consumer appeal (Little, 1973).
Thus, both color and instrumental measurements of the different treatments for JBP and
CMP should be taken into consideration when fine-tuning the parameters of this
treatment to ensure consumer acceptability.
Texture: Hardness and Crunchiness
As shown in Table 9, only variations within the WPI concentrations produced
significant differences in texture, specifically sensory and instrumental hardness,
crunchiness, and crust work. However, CMP alone showed significant differences in all
the aforementioned attributes while only the sensory hardness for JBP was affected by
variations in WPI concentration.
Hardness was defined as the force required to bite through a sample (Meilgaard et
al., 1999) while crunchiness reflects the amount of sound and fracturability detected
when the sample is chewed once with the molars (Vickers, 1987). The panel rated JBP
treated with 0% WPI to be significantly softer compared to control and other WPI
concentrations while the sensory hardness for CMP was rated in the order of control =
0% = 5% > 2.5% = 10% WPI. While the instrumental measurements did not show any
differences for hardness for JBP, it showed that CMP were significantly harder and have
higher crust fracture in the presence of WPI. The sensory and instrumental measurements
of crunchiness suggest that treating patties with WPI increases the crunchiness of the
patties independent of pH levels, but this effect could only be perceived at high WPI
concentrations (e.g., 10% WPI). The inconsistency could be attributed to the fact that
unlike the instrumental measurement of crunchiness, sensory crunchiness was judged not
only based on the force it took to bite through the sample, but also the amount of sound
produced. Various studies have shown that the amplitude of sound generated when biting
through a sample correlated well with perceived crunchiness (Antonova et al., 2003;
Vickers, 1987).
Because the instrumental measurements of texture involves the penetration of the
crust region, it is suspected that the components of the crust such as the amount of batter,
breading, and/or whey pickup and crust thickness affected these textural properties.
When ANCOVA was used to analyze the effects of these factors on CMP instrumental
hardness and crust fracture, it was observed that only crust thickness significantly
affected both instrumental hardness and crust fracture (p < 0.05). When the effects of
these factors were analyzed for CMP crust fracture, it was also observed that only crust
thickness significantly affected the variable (p < 0.05). Correlation analysis on crust
thickness and instrumental hardness and crust fracture showed that crust thickness was
positively correlated with crust fracture (r = 0.585, p < 0.01) but was not significantly
correlated with instrumental hardness. These observations may explain why JBP did not
show any significant differences for hardness and crust fracture (see Table 9).
Another factor that may contribute to the difference in crust fracture or
crunchiness of the patties is the moisture content (Antonova et al., 2003). Moisture
content was observed to be significantly lower in CMP treated with 5% and 10% WPI.
This may contribute to the significantly higher crust fracture for CMP treated with 5%
and 10% (see Table 7). In addition, the sensory panel rated CMP treated with 10% WPI
to be the crunchiest of all the treatments. Moisture reduces the crunchiness of a food
product by weakening the solid matrix (Katz & Labuza, 1981; Van Vliet et al., 2007) due
to breakage of the macromolecular interactions of the food structure by water-water
interactions. This causes the macromolecules to be more mobile and slide against each
other and this is perceived as a reduction in crunchiness (Katz & Labuza, 1981). Thus,
the results suggest that treatments that lead to lowering of moisture content (e.g., at 10%
WPI) increase crunchiness of the battered and breaded product.
Mouth Feel Sensation and Flavor
The results for the sensory attributes that describe mouth feel sensation and flavor
are shown in Table 10. None of these attributes were observed to be significantly
different when compared to the control and between the treatments except for bitterness
in JBP as WPI concentration is varied. Panelists rated those treated with 10% WPI to be
significantly more bitter compared to the control. However, since no other independent
variable variations for both JBP and CMP produced a significant difference in bitterness,
the observed result may be due to the psychological errors of the panelists, and these
errors might include those due to expectation, preference, environment, and fatigue
(Stone & Sidel, 1985). Overall, treating patties with WPI solutions at various pH levels
and WPI concentrations did not significantly affect the general mouth feel sensation and
flavor of the patties.
Conclusion
WPI exhibits lipid barrier properties that are dependent on both pH and protein
concentration when used as a postbreading dip in battered and breaded fried chicken
patties. The highest lipid reduction was obtained when 5% and 10% WPI solutions were
used at low pH levels (pH 2 and 3) for both breading systems. Lipid reduction ranged
from 31.24% for CMP at pH 2 with 5% WPI and 37.5% for JBP at pH 2 with 10% WPI.
Treatment of deep-fried, battered, and breaded chicken patties with WPI did not
cause any perceivable changes in the flavor of the product although color, perceived
hardness, and perceived crunchiness were significantly affected. WPI concentrations
were observed to have different effects on the two breading systems where JBP were
darker and less yellow when treated with 5% and 10% WPI while CMP were lighter and
more yellow compared to the control across all WPI concentrations. Patties treated at pH
2 and 3 did not produce any perceivable color changes but had significantly lower L* and
b* values and higher a* values compared to the other treatments. As for hardness, patties
treated with the WPI dip were either perceived to be harder or similar in hardness
compared to the control. Instrumental measurements confirms the sensory evaluations by
showing a significant increase in hardness and crust fracture for patties treated with 2.5%,
5%, and 10% WPI. Thus, JBP that showed the highest lipid reduction (10% WPI at pH 2)
were observed to be darker, less yellow, more bitter, but did not produce any perceivable
changes in hardness, crunchiness, mouth feel, and flavor while CMP with the lowest lipid
content (5% WPI at pH 2) were darker, more yellow, and are perceived to be crunchier,
but were not perceived to be different in mouth feel, taste, and flavor.
The usage of WPI as a postbreading dip is a promising alternative in reducing fat
content in fried foods since it could simultaneously fulfill the steady demand for fried
foods and contribute to the growing effort of Americans to consume less fat. In addition,
this treatment was observed to be versatile due to the comparable effectiveness in
reducing fat uptake for both breading systems despite the difference between the
composition, structure, and size of the breadings. Despite the significant effect of the
WPI postbreading dip on the color, hardness, and crunchiness of the deep-fried, battered,
and breaded chicken patties, these changes may not deter consumers who place more
emphasis on reducing their fat consumption. In short, while there is still room for
improving this treatment to minimize the effect on color and texture, the usage of WPI as
a postbreading dip is a promising alternative in reducing fat content in fried foods since it
does not alter the flavor profile of a full-fat product.
Future Studies
The results of this research suggests the need for further investigation to further
the understanding of the mechanism and versatility of WPI as a postbreading dip in
reducing oil absorption. Specific to whey, the role of each protein fraction in contributing
to the lipid barrier properties of whey protein isolate should be investigated. These
fractions could be separated out and combinations of protein fractions could be used to
make the postbreading dip and the effects on final lipid content could then be analyzed.
In addition, future studies could focus on the optimization of the WPI treatment in
reducing oil absorption in fried foods by investigating (a) effects of variations of the
substrate that is being fried, particularly vegetable vs. meat products, (b) variations in
product composition (e.g., batter formulation, breading types, battered and breaded vs.
not battered and breaded), and (c) variations in processing methods such as par-fried vs.
fully fried, differences in rethermalization methods such as oven baking vs. microwave
heating, and various storage conditions (e.g., frozen par-fried, frozen fully-fried, changes
throughout refrigerated and frozen storage). In relation to the food industry, consumer
sensory tests should be conducted to investigate the overall acceptability of the treatment
and the product that is being treated, in addition to continuous descriptive sensory
analysis.
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APPENDIX A: IRB FORM
APPENDIX B: TIMELINE FOR SENSORY SELECTION, TRAINING, AND
SAMPLING
Session
Date
Info session 2/1/07
2/7/07
3/6/07
3/7/07
3/8/07
Description
• Giving out information concerning basic sensory
analysis.
• Those interested were asked to fill in a
questionnaire (see Appendix C)
Training session 1 4/26/07
• Panel were asked to sign informed consent form
(see Appendix D)
• Identification and rating of basic tastes (see
Appendix E)
Training session 2 5/10/07
• Identification and rating of mixtures of basic
tastes (see Appendix F)
Training session 3 5/15/07
• Introduction to lexicon development: cookie
variations (see Appendix G)
Training session 4 5/22/07
• Introduction to standard intensity scale for
hardness (see Appendix H)
• Continuation of lexicon development : fried oat
bran patties (see Appendix K)
Training session 5 5/24/07
• Introduction to standard intensity scale for
crispness (see Appendix I)
• Continuation of rating of hardness using
standard references (see Appendix L)
Training session 6 5/31/07
• Continuation of rating of crispness using
standard references (see Appendix M)
Training session 7 7/10/07
• Continuation of rating of hardness and crispness
using standard references (see Appendix N)
Training session 8 7/12/07
• Continuation of lexicon development: fried
dough balls (see Appendix O)
Training session 9 7/17/07
• Continuation of rating of crispness using
standard references (see Appendix P)
Training session 10 7/19/07
• Review of basic taste identification and rating
for hardness and crispness using standard
references (see Appendix Q)
Training session 11 7/24/07
• Introduction to standard intensity scale for
juiciness (see Appendix J and R)
Training session 12 7/26/07
• Continuation of rating of juiciness using
standard references (see Appendix S)
Training session 13 8/14/07
• Lexicon development for cooked ground
chicken (see Appendix T)
Training session 14 8/16/07
• Introduction to rating using a 15-cm line scale
for attributes for cooked ground chicken (see
Appendix U)
Training session 15 9/20/07
• Lexicon development for fried, battered, and
breaded chicken products (see Appendix V)
Training session 16 9/25/07
• Continuation of lexicon development for fried,
battered, and breaded chicken products
Training session 17 9/27/07
• Fine-tuning of lexicon for fried, battered, and
breaded chicken patties using the 15-cm line
scale
Calibration for 10/2/07
CMP
• Calibration of attribute rating with warm-up
CMP sample
Calibration for 10/4/07
CMP
• Calibration of attribute rating with warm-up
CMP sample
CMP sampling 10/9/07
session 1
• Sampling of CMP
• Ballot (see Appendix W)
• Order or sampling (see Appendix Y)
CMP sampling 10/11/07
session 2
CMP sampling 10/12/07
session 3
Calibration for JBP 10/23/07
• Calibration of attribute rating with warm-up JBP
sample
JBP sampling 10/30/07
session 1
JBP sampling 11/1/07
session 2
JBP sampling 11/6/07
session 3
JBP sampling 11/8/07
session 4
JBP sampling 11/9/07
session 5
• Sampling of JBP
• Ballot (see Appendix X)
• Order or sampling (see Appendix Z)
APPENDIX C: SENSORY PANEL QUESTIONNAIRE
HISTORY:
Name: __________________________________________________________________
Address: ________________________________________________________________
Phone (home and business): _________________________________________________
Email: __________________________________________________________________
TIME:
1. Are there any weekdays (M-F) that you will not be available on a regular
basis?_________________
2. How many weeks of vacation do you plan to take in 2007? _____________________
________________________________________________________________________
HEALTH:
1.
Do you have any of the following?
Dentures
_____
Diabetes
_____
Oral or gum disease
_____
Hypoglycemia
_____
Food allergies
_____
Hypertension
_____
2.
Do you take any medications that affect your senses, especially taste and smell? ___
________________________________________________________________________
FOOD HABITS:
1. Are you currently on a restricted diet? If yes, explain
_____________________________________________________________________
2. How often do you eat out in a month? ______________________________________
3. How often do you eat fast food in a month? _________________________________
4. What is (are) your favorite food(s)? ________________________________________
5. What is (are) your least favorite food(s)? ___________________________________
6. What is (are) your least favorite food(s)? ___________________________________
7. What foods can you not eat? _____________________________________________
8. What foods do you not like to eat? ________________________________________
9. If you ability to distinguish smell and tastes:
Better than average
Average
Worse than average
SMELL
______
______
______
TASTE
______
______
______
10. Does anyone in your immediate family work for a food company? _______________
11. Does anyone in your immediate family work for an advertising company or a
marketing research agency? ______________________________________________
QUICK QUIZ:
1. How would you describe the difference between flavor and aroma?
_____________________________________________________________________
2. What is the best one or two word description of grated Italian cheese (Parmesan or
Romano)?
_____________________________________________________________________
3. Describe some of the noticeable flavors in cola
_____________________________________________________________________
APPENDIX D: CONSENT FORM
OHIO UNIVERSITY
CONSENT FORM
Optimization of the Pre-treatment to Reduce Oil Absorption in Frozen Pre-fried Breaded
Products Using Whey Protein Isolate
You are being asked to participate in a research study. Participation in this study is
completely voluntary. Please read the information below and ask questions about
anything that you do not understand before deciding if you want to participate. A
researcher listed below will be available to answer your questions.
RESEARCH TEAM AND SPONSORS
Principal Investigator:
Dr. Robert G. Brannan
Associate Professor
Department of Human and Consumer Sciences
(740) 593-2879
Co-Investigator
Eunice Mah
Department of Human and Consumer Sciences
(740) 590-1871
PURPOSE OF STUDY
The purpose of this research study is to study the effectiveness of whey protein isolate
coating in reducing oil absorption into fully battered and breaded deep-fried foods when
applied post-breading.
ELIGIBILITY
Potential participants will be screened based on the information obtained from the
attached questionnaire.
PROCEDURES
If you agree to participate you will be involved in a series of training for several sessions
spanning several weeks where you will be familiarized with the methods used in sensory
analysis of foods. Training will involve tasting various food products to test for texture
and flavor acuity and developing terminology to describe the food product. After
completing the training session, you will be called upon to taste and describe deep fried
chicken patties that treated with the whey protein isolate coating. Ballots containing
terminologies that were developed will be used as guidelines. You will be working as a
group throughout the duration of the study. Each training and tasting session is estimated
to be no more than an hour and will be scheduled according to the availability of the
group.
RISKS, STRESS, OR DISCOMFORT
Risks associated with participating in this study will be minimal to none. You will be
screened according to the food allergies or medical conditions that you will be asked to
list in the attached questionnaire.
UNKNOWN RISKS
There may be risks to being in this study that we don't know about now. You will be
informed of any changes in the way the study will be done and any additional identified
risks to which you may be exposed.
BENEFITS
The level of fat intake for the average American is four percent higher than the maximum
recommended total dietary fat. High intake of fat is associated with increased risk for
many diseases and therefore, consumers are encouraged to adopt a low- or reduced-fat
diet. Research into reducing fat/oil absorption during deep-fat frying using natural
ingredients may offer more varieties of low- or reduced-fat foods in the market.
___________________________________________________________________
Printed name of researcher
Signature of researcher
Date
Subject’s statement
This study has been explained to me. I volunteer to take part in this research. I have had
a chance to ask questions. If I have general questions about the research, I can ask one of
the researchers listed above. If I have questions regarding my rights as a participant, I can
call Jo Ellen Sherow, Director of Research Compliance, Ohio University, (740)593-0664.
This project has been reviewed and approved for human participation by the Ohio
University IRB. I will receive a copy of this consent form.
___________________________________________________________________
Printed name of subject
Signature of subject
Date
APPENDIX E: TRAINING SESSION 1
Date: April 26, 2007
Venue: Grover Center W120
Objectives:
o Basic panel screening and calibration
o Developing skills of rating taste intensities without the distraction of aromatics
Test Design:
o Panel will familiarize themselves with the reference set
o Panel will then taste the evaluation set and record their impressions using the score
sheet provided.
o Reference set: All 6 samples are clearly labeled and placed on individual serving trays
(10 ml per sample).
o Evaluation set: All 9 samples are clearly labeled with codes and placed on individual
serving trays in random order (10 ml per sample).
o The scores will be averaged and analyzed.
Materials:
Assume 20 participants and 10ml serving size
o
o
o
o
o
o
300* plain plastic serving cups, 2-oz size
20 individual serving trays
20 large plastic cups with lid (spit cups), 16-oz size
20 water rinse cups, 6-oz size
5 water serving pitchers
1 packet napkins
*(6 reference solution + 9 evaluation solution) x 20 = 300 samples
Evaluation set 1
Label
Content ( in 250 ml
water)
Salty
0.10 g salt
Salty
0.15 g salt
Salty
0.25 g salt
Sweet
0.5 g sugar
Sweet
1 g sugar
Sweet
2 g sugar
Sour
0.05 g citric acid
Sour
0.07 g citric acid
Sour
0.10 g citric acid
Umami
0.025 g umami
Umami
0.05 g umami
Umami
0.1 g umami
Code
852
796
936
374
710
611
485
918
660
991
384
968
Preparation of solution:
o Bulk solution can be prepared one day ahead and refrigerated.
o For evaluation set, solutions are prepared by mixing equal quantities of the appropriate
reference solutions.
o On the day of the test, all samples are allowed to warm to room temperature
`BASIC TASTE SCORECARD
Date:
Name:
Characteristic studied: Basic taste
Instructions:
You have 3 samples on the tray in front of you.
Taste the samples from left to right.
Identify the taste (sweet, sour, salty, or umami).
Rank the taste intensity by recording the codes in the appropriate space (1 being the
weakest and 3 being the strongest).
Set 1
Basic taste: ____________
Intensity rank:
1. _______
2. _______
3. _______
2. _______
3. _______
2. _______
3. _______
2. _______
3. _______
Set 2
Basic taste: ____________
Intensity rank:
1. _______
Set 3
Basic taste: ____________
Intensity rank:
1. _______
Set 4
Basic taste: ____________
Intensity rank:
1. _______
BASIC TASTE SCORECARD
Date:
Name:
Characteristic studied: Basic taste
Instructions:
You have four samples on the tray in front of you.
Record down the sample code before tasting the sample.
Taste the samples from left to right and indicate the taste by checking the appropriate
space.
Do not repeat the evaluation of previous samples.
Sample Code
Sweet
Sour
Salty
Umami
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
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APPENDIX F: TRAINING SESSION 2
Date: May 10th, 2007
Venue: Grover Center W313
Objectives:
o Basic panel screening and calibration
o Developing skills of rating taste intensities without the distraction of aromatics
Test Design:
o Panel will familiarize themselves with the reference set
o Panel will then taste the evaluation set and record their impressions using the
score sheet provided.
o Reference set: All 6 samples are clearly labeled and placed on individual serving
trays (10 ml per sample).
o Evaluation set: All 9 samples are clearly labeled with codes and placed on
individual serving trays in random order (10 ml per sample).
o The scores will be averaged and analyzed.
Materials:
Assume 20 participants and 10ml serving size
o
o
o
o
o
o
300* plain plastic serving cups, 2-oz size
20 individual serving trays
20 large plastic cups with lid (spit cups), 16-oz size
20 water rinse cups, 6-oz size
5 water serving pitchers
1 packet napkins
*(6 reference solution + 9 evaluation solution) x 20 = 300 samples
Evaluation set
Content
Sucrose/citric acid
Sucrose/NaCl
Sucrose/umami
Citric acid/umami
Citric acid/NaCl
NaCl/umami
Code
246
425
132
861
388
258
BASIC TASTE SCORECARD
Date:
Name:
Characteristic studied: Basic taste
Instructions:
You have six samples on the tray in front of you.
Record down the sample code before tasting the sample.
Taste the samples from left to right and indicate the taste by checking the appropriate
space.
Do not repeat the evaluation of previous samples.
Sample Code
Sweet
Sour
Salty
Umami
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APPENDIX G: TRAINING SESSION 3
Date: May 15th, 2007
Venue: Grover Center E120
Objectives:
o Introduce lexicon development to panel
Test Design:
o Panel will be asked to generate a lexicon for different cookie variations (refer to
table below).
Code
Cookie Variation
762
Flour, water margarine
806
Flour, water, sugar
427
Flour, water, margarine, sugar
800
Flour, water, sugar, egg, margarine, vanilla
Ingredients
2 ½ C flour
1 C water
2 ½ C flour
1 C water
½ C + 2 T margarine
2 ½ C flour
1 C water
½ C + 2 T margarine
1 C white granulated sugar
2 ½ C flour
1 C water
1 C white granulated sugar
1 egg
½ C + 2 T margarine
1 t pure vanilla extract
o Method:
o Prepare each recipe as shown in table.
o Spread dough into 9 x 13 oblong non-stick baking pan. Precut into squares
before baking.
o Bake at 350 for 35 minutes
o Store in airtight containers.
Cookie Variation Exercise Worksheet
Date:
Name:
Instructions:
You have four samples on the tray in front of you.
Record down the sample code before tasting the sample.
Taste the samples and describe the flavor, texture, and appearance.
Code
Description
APPENDIX H: STANDARD INTENSITY HARDNESS SCALE
Scale value
Product
Brand/Type/Manufacturer
Sample size
1
Cream cheese
Kraft/Philadelphia light
½ in cube
2.5
Egg white
Hard cooked
½ in cube
4.5
Cheese
Yellow American pasteurized
½ in cube
process
1 olive pimento,
6
Olives
Goya foods/giant size, stuffed
removed
Large, cooked 5 min/Hebrew
7
½ in slice
Frankfurter
national
Cocktail type in vacuum
9.5
Peanuts
1 nut, whole
tin/Planters
11
Carrots
Uncooked, fresh, unpeeled
½ in slice
14.5
Hard candy
Lifesavers
3 pieces, one color
APPENDIX I: STANDARD INTENSITY CRISPNESS SCALE
Scale value
Product
Brand/Type/Manufacturer
Sample size
2
Granola bar
Quaker Low Fat Chewy Chunk
1/3 bar
5
Club cracker
Keebler Partner Club Cracker
½ cracker
6.5
Graham cracker
Honey Maid
1 in square
7
Oat cereal
Cheerios
1 oz
9.5
Bran flakes
Kellogg’s Bran Flakes Cereal
1 oz
Cheese crackers
Pepperidge Farm Cheddar Cheese
goldfish
Crackers
Corn flakes
Kellogg’s Corn Flakes Cereal
11
14
1 oz
1 oz
APPENDIX J: STANDARD INTENSITY JUICINESS SCALE
Scale value
Product
Brand/Type/Manufacturer
Sample size
1
Banana
Raw
½ inch slice
2
Carrot
Raw
½ inch slice
4
Mushroom
Raw
½ inch slice
7
Snap beans
Raw
5 pieces
8
Cucumber
Raw
½ inch slice
10
Apple
Raw
½ inch wedge
12
Honeydew melon
Raw
½ inch cube
15
Watermelon
Raw
½ inch cube
APPENDIX K: TRAINING SESSION 4
Date: May 22, 2007
Venue: Grover Center W320
Objectives:
o Familiarize panel with intensity scale values using references
o Practice lexicon development
Test Design:
o Panel will be asked to taste references for hardness.
o Panel will be asked to come up with a lexicon for fried oat bran patties
Standard reference for hardness
Scale value
1
2.5
4.5
Sample
Cream cheese
Egg white
Cheese
Olives
6
Frankfurter
7
9.5
11
14.5
Peanuts
Carrots
Hard candy
brand
Kraft/Philadelphia light
Hard cooked
Yellow American pasteurized
process/ land O’lakes
Goya foods/giant size, stuffed
Large, cooked 5 min/Hebrew
national
Cocktail type in vacuum
tin/Planters
Uncooked, fresh, unpeeled
lifesavers
Sample size
½ in cube
½ in cube
½ in cube
1 olive pimento,
removed
½ in slice
1 nut, whole
½ in slice
3 pieces, one color
o Panelists will be presented with all the reference samples and asked to familiarize
themselves with the scale values.
o Prepare out bran patties (instructions to follow) and present it to the panel to form
a lexicon for the product. Group discussion.
o Oat bran patties:
Ingredients:
1 C Kroger’s Oat Bran Muffin Mix ®
¼ C water
Method:
Mix the two ingredients together to form a paste. Drop a tablespoon of batter
into a pre-heated deep fryer (375F) and fry until golden brown. Drain excess
oil with paper towel. Serve at room temperature
Lexicon Exercise Worksheet
Name:
Instructions:
You have a sample on the tray in front of you.
Record down the sample code before tasting the sample.
Taste and describe the sample according to the instructions provided.
1. Look at the sample (without touching) and describe the appearance. Give attention to
characteristics such as surface moisture, surface roughness (smoothness), and color.
2. Place sample between incisors and bite down evenly.
Evaluate the force required to bite through the food. Refer to the reference scale for
hardness.
3. Describe the flavor and aroma of the product. Include perception of basic tastes
(sweet, sour, salty, bitter, umami)
APPENDIX L: TRAINING SESSION 5
Date: May 24, 2007
Venue: Grover Center W320
Objectives:
o Familiarize panel with intensity scale values using references
Test Design:
o Panel will be asked to taste references for crispness.
o Panel will be evaluated for rating of hardness intensity
o
o
o
o
Standard references for crispness scale:
Scale reference
brand
Sample size
value
2
Granola bar
Quaker low fat chewy chunk
1/3 bar
5
Club cracker
Keebler partner club cracker
½ cracker
6.5
Graham cracker
Honey maid
1 in square
7
Oat cereal
Cheerios
1 oz
9.5
Bran flakes
Kellogg’s bran flakes cereal
1 oz
11
Cheese crackers
Pepperidge farm cheddar cheese
1 oz
goldfish
crackers
14
Corn flakes
Kellogg’s corn flakes cereal
1 oz
Panelists will be presented with all the reference samples and asked to
familiarize themselves with the scale values.
Evaluation for hardness intensity
Code
Sample
brand
816
Cream cheese
Kraft/Philadelphia light
327
Egg white
Hard cooked
762
Cheese
Yellow American pasteurized
process/ land O’lakes
841
Olives
Goya foods/giant size, stuffed
994
Frankfurter
953
Peanuts
615
756
Carrots
Hard candy
Large, cooked 5 min/Hebrew
national
Cocktail type in vacuum
tin/Planters
Uncooked, fresh, unpeeled
lifesavers
Sample size
½ in cube
½ in cube
½ in cube
1 olive pimento,
removed
½ in slice
1 nut, whole
½ in slice
3 pieces, one
color
Panelists will be presented with all the samples and asked to rate the hardness
intensity of the samples. Answers will be compared to the standard references
for hardness (refer to training session 4).
Hardness Intensity Exercise Worksheet
Date:
Name:
Instructions:
Record down the sample code before tasting the sample.
Taste the samples and rate the crispness of the samples. Scale values 1 and 14.5 have
been identified for you.
Do not discuss with other panel members.
Code
Scale value
816
1
756
14.5
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APPENDIX M: TRAINING SESSION 6
Date: May 31, 2007
Venue: Grover Center W320
Objectives:
o Familiarize panel with intensity scale values using references
Test Design:
o Evaluation of panel’s perception of crispness.
Evaluation of panel’s perception on crispness:
Code
451
124
682
914
694
385
685
reference
Granola bar
Club cracker
Graham
cracker
Oat cereal
Bran flakes
Cheese
crackers
goldfish
Corn flakes
brand
Quaker low fat chewy chunk
Keebler partner club cracker
Honey maid
Sample size
1/3 bar
½ cracker
1 in square
Cheerios
Kellogg’s bran flakes cereal
Pepperidge farm cheddar cheese
crackers
1 oz
1 oz
1 oz
Kellogg’s corn flakes cereal
1 oz
o Panel will be presented with the samples.
o Panel will be asked to rank the crispness of the samples using a 15-point scale (1
= not crisp/soggy, 15 = very crisp).
o Results will be compared to the reference set (refer to training session 5)
Crispness Intensity Exercise Worksheet
Date:
Name:
Instructions:
Record down the sample code before tasting the sample.
Taste the samples and rate the crispness of the samples. Scale value 1 and 15 have been
identified for you.
Do not discuss with other panel members.
Code
Scale value
451
1
685
15
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APPENDIX N: TRAINING SESSION 7
Date: July 10th, 2007
Venue: Grover Center E120
Objectives:
o Re-familiarize panel with intensity scale values using references
Test Design:
o Panel will be asked to taste references for hardness and crispness.
o
o
o
o
Standard hardness scale reference:
Scale
Reference
brand
value
1
Cream cheese
Kraft/Philadelphia light
2.5
Egg white
Hard cooked
4.5
Cheese
Yellow American pasteurized
process/ land O’lakes
6
Olives
Goya foods/giant size, stuffed
7
Frankfurter
9.5
Peanuts
11
14.5
Carrots
Hard candy
Large, cooked 5 min/Hebrew
national
Cocktail type in vacuum
tin/Planters
Uncooked, fresh, unpeeled
lifesavers
Sample size
½ in cube
½ in cube
½ in cube
1 olive pimento,
removed
½ in slice
1 nut, whole
½ in slice
3 pieces, one color
Standard crispness scale reference:
Scale Reference
brand
value
2
Granola bar
Quaker low fat chewy chunk
5
Club cracker
Keebler partner club cracker
6.5
Graham cracker
Honey maid
7
Oat cereal
Cheerios
9.5
Bran flakes
Kellogg’s bran flakes cereal
11
Cheese crackers
Pepperidge farm cheddar cheese
goldfish
crackers
14
Corn flakes
Kellogg’s corn flakes cereal
Sample size
1/3 bar
½ cracker
1 in square
1 oz
1 oz
1 oz
1 oz
Present the standards to panel and ask them to re-familiarize themselves with
the scale.
Practice using the scale with the following product:
o Apple (113)
o Ginger snaps (260)
o Saltine crackers (185)
o Lima beans (336)
Scorecard 7a (hardness)
Name:
Instructions:
You have a sample on the tray in front of you.
Record down the sample code before tasting the sample.
Follow the instructions.
Sample code: ___________
Place sample between your front teeth and bite through the sample once.
Evaluate the hardness. Refer to the reference scale for hardness.
Sample code: ___________
Place sample between your front teeth and bite through the sample once.
Evaluate the hardness. Refer to the reference scale for hardness.
Sample code: ___________
Place sample between your front teeth and bite through the sample once.
Evaluate the hardness. Refer to the reference scale for hardness.
Sample code: ___________
Place sample between your front teeth and bite through the sample once.
Evaluate the hardness. Refer to the reference scale for hardness.
Scorecard 7b (crispness)
Name:
Instructions:
You have a sample on the tray in front of you.
Record down the sample code before tasting the sample.
Follow the instructions.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the crispness. Refer to the reference scale for crispness.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the crispness. Refer to the reference scale for crispness.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the crispness. Refer to the reference scale for crispness.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the crispness. Refer to the reference scale for crispness.
APPENDIX O: TRAINING SESSION 8
Date: July 12, 2007
Venue: Grover Center E120
Objectives:
o Familiarize panel with intensity scale values using references
Test Design:
o Panel will be asked to generate a lexicon for fried dough balls (preparation
instructions follows)
Instructions:
o Prepare the following product:
Fried dough balls
Ingredients:
• 1 cup water
• 2 1/2 tablespoons white sugar
• 1/2 teaspoon salt
• 2 tablespoons vegetable oil
• 1 cup all-purpose flour
• 2 quarts oil for frying
Methods:
o In a small saucepan over medium heat, combine water, 2 1/2
tablespoons sugar, salt and 2 tablespoons vegetable oil. Bring to a
boil and remove from heat. Stir in flour until mixture forms a ball.
o Heat oil for frying in deep-fryer or deep skillet to 375 degrees F (190
degrees C). Drop balls of dough into hot oil. Fry until golden; drain
on paper towels.
o Sample is coded 312 and presented to the panel.
o Panelists were asked to describe the product.
Lexicon Exercise Worksheet
Name:
Instructions:
You have a sample on the tray in front of you.
Record down the sample code before tasting the sample.
Taste and describe the sample according to the instructions provided.
Sample code: ___________
1. Look at the sample (without touching) and describe the appearance. Give
attention to characteristics such as surface moisture, surface roughness
(smoothness), and color. Try to rate the hardness and crispness of the product.
APPENDIX P: TRAINING SESSION 9
Date: July 17, 2007
Venue: Grover Center W320
Objectives:
o Familiarize panel with intensity scale values using references
o Generate lexicon for cooked ground chicken
Test Design:
o Evaluation of panel’s perception of crispness.
Code
451
124
682
914
694
385
685
reference
Granola bar
Club cracker
Graham cracker
Oat cereal
Bran flakes
Cheese crackers
goldfish
Corn flakes
brand
Quaker low fat chewy chunk
Keebler partner club cracker
Honey maid
Cheerios
Kellogg’s bran flakes cereal
Pepperidge farm cheddar cheese
crackers
Kellogg’s corn flakes cereal
Sample size
1/3 bar
½ cracker
1 in square
1 oz
1 oz
1 oz
1 oz
o Panel will be presented with the samples.
o Panel will be asked to rank the hardness of the samples using a 15-point scale
(1 = not crisp/soggy, 15 = very crisp).
o Results will be compared to the reference set (refer to training session 4)
o Generate lexicon for cooked ground chicken
o Panel will be presented with cooked ground chicken (ground chicken
cooked in a bag in boiling water for 15 minutes.
o Record and discuss attributes that are listed by panelists.
Crispness Intensity Exercise Worksheet
Date:
Name:
Instructions:
Record down the sample code before tasting the sample.
Taste the samples and rate the crispness of the samples. Scale value 1 and 15 have been
identified for you.
Do not discuss with other panel members.
Code
Scale value
451
1
685
15
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APPENDIX Q: TRAINING SESSION 10
Date: July 19, 2007
Venue: Grover Center E120
Objectives:
o
Practice of basic taste recognition
o
Practice of usage of intensity scale values using references for hardness and crispness
Test Design:
o
Panel will go through basic taste recognition.
o
Reference set:
Label
Content ( in 250 ml water)
Salty
0.10 g salt
Sweet
0.5 g sugar
Sour
0.05 g citric acid
Bitter
Umami
0.025 g umami
o
o
Practice set:
Label
Sweet + sour
Salty + bitter
Sweet + umami
Sweet + bitter
Code
226
933
693
148
Panel will be asked to taste references for hardness and crispness
o
Standard hardness scale reference:
Scale
reference
brand
value
1
Cream cheese
Kraft/Philadelphia light
2.5
Egg white
Hard cooked
4.5
Cheese
Yellow American pasteurized process/
land O’lakes
6
Olives
Goya foods/giant size, stuffed
7
9.5
11
14.5
o
Frankfurter
Peanuts
Carrots
Hard candy
Large, cooked 5 min/Hebrew national
Cocktail type in vacuum tin/Planters
Uncooked, fresh, unpeeled
lifesavers
Standard crispness scale reference:
Scale
reference
value
2
Granola bar
5
Club cracker
6.5
Graham cracker
7
Oat cereal
9.5
Bran flakes
11
Cheese crackers
goldfish
14
Corn flakes
o
o
o
o
Sample size
½ in cube
½ in cube
½ in cube
1 olive pimento,
removed
½ in slice
1 nut, whole
½ in slice
3 pieces, one color
brand
Sample size
Quaker low fat chewy chunk
Keebler partner club cracker
Honey maid
Cheerios
Kellogg’s bran flakes cereal
Pepperidge farm cheddar cheese
crackers
Kellogg’s corn flakes cereal
1/3 bar
½ cracker
1 in square
1 oz
1 oz
1 oz
Present samples to panelists in order of scale value.
Allow panelists to familiarize themselves with the scale.
Practice applying the hardness reference scale on:
ƒ
Yellow cake (254)
ƒ
Lima beans (353)
Practice applying the crispness reference scale on:
ƒ
Melba toast (376)
ƒ
popcorn (981)
1 oz
Scorecard 10a (basic tastes)
Name:
Instructions:
You have four samples on the tray in front of you.
Record down the sample code before tasting the sample.
Taste the samples from left to right and indicate the taste by checking the appropriate
space.
Do not repeat the evaluation of previous samples.
Sample Code
Sweet
Sour
Salty
Bitter
Umami
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
______
Scorecard 10b (hardness)
Name:
Instructions:
You have a sample on the tray in front of you.
Record down the sample code before tasting the sample.
Follow the instructions.
Sample code: ___________
Place sample between your front teeth and bite through the sample once.
Evaluate the hardness. Refer to the reference scale for hardness.
Sample code: ___________
Place sample between your front teeth and bite through the sample once.
Evaluate the hardness. Refer to the reference scale for hardness.
Scorecard 10c (crispness)
Name:
Instructions:
You have a sample on the tray in front of you.
Record down the sample code before tasting the sample.
Follow the instructions.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the crispness. Refer to the reference scale for crispness.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the crispness. Refer to the reference scale for crispness.
APPENDIX R: TRAINING SESSION 11
Date: July 24, 2007
Venue: Grover Center E120
Objectives:
o Practice of usage of intensity scale values using references for juiciness
Test Design:
o Panel will be asked to taste references juiciness
o Panel will practice on chicken products and frankfurter.
o Standard juiciness scale reference:
Scale value Reference
1
Banana
2
Carrot
4
Mushroom
7
Snap beans
8
Cucumber
10
Apple
12
Honeydew melon
15
Watermelon
Type
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Sample size
½ inch slice
½ inch slice
½ inch slice
5 pieces
½ inch slice
½ inch wedge
½ inch cube
½ inch cube
o Present samples to panelists in order of scale value.
o Allow panelists to familiarize themselves with the scale.
o Practice applying the juiciness reference scale on the products prepared:
o Banquet Chicken Breast Nuggets®
o Banquet Chicken Breast Patties®
o Hebrew National frankfurter®
Scorecard 11
Name:
Instructions:
You have three samples on the tray in front of you.
Record down the sample code before tasting the sample. Taste the samples from left to
right.
Follow the instructions.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the juiciness. Refer to the reference scale for juiciness.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the juiciness. Refer to the reference scale for juiciness.
Sample code: ___________
Place sample between your molars and bite through twice.
Evaluate the juiciness. Refer to the reference scale for juiciness.
APPENDIX S: TRAINING SESSION 12
Date: July 26, 2007
Venue: Grover Center E120
Objectives:
o Practice of usage of intensity scale values using references for juiciness
Test Design:
o Panel will be asked to taste references juiciness
o Panel will practice on chicken products and frankfurter.
o Standard juiciness scale reference:
Code
Reference
163
Banana
401
Carrot
947
Mushroom
755
Snap beans
261
Cucumber
615
Apple
630
Honeydew melon
435
Watermelon
Type
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Raw
Sample size
½ inch slice
½ inch slice
½ inch slice
5 pieces
½ inch slice
½ inch wedge
½ inch cube
½ inch cube
o Panel will be presented with the samples.
o Panel will be asked to rank the hardness of the samples using a 15-point scale
(1 = not juicy, 15 = very juicy).
o Results will be compared to the reference set (refer to training session 11)
Juiciness Intensity Exercise Worksheet
Date:
Name:
Instructions:
Record down the sample code before tasting the sample.
Taste the samples and rate the juiciness of the samples. Scale value 1 and 15 have been
identified for you.
Do not discuss with other panel members.
Code
Scale value
163
1
435
15
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______
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______
______
______
______
______
______
______
______
______
APPENDIX T: SENSORY ATTRIBUTES FOR COOKED GROUND CHICKEN
Sensory attributes and its description and anchored references, and their position on the 15-cm line scale as
identified for cooked ground chicken.
Attribute
Description
Reference/Brand/Preparation
Color
Color of the outer surface of the sample
Boiled chicken breast
Boiled beef
Position
(cm)
1
15
Chicken brothy
Aromatics associated with chicken broth
Chicken broth
9.9
Fishy
Aromatics associated with cooked fish
Boiled fish
9.9
Sulfury
Aromatics associated with boiled egg yolk
Boiled egg yolk
5.0
Musty
Aromatics associated with wet cardboard
Wet cardboard
4.0
Sweet
The amount of sweet taste detected from
the sample as it is being chewed before
being swallowed or expectorated.
5% sucrose solution
5.0
Sour
The amount of sweet taste detected from
the sample as it is being chewed before
being swallowed or expectorated.
0.8% citric acid solution
5.0
Salty
The amount of salty taste detected from
the sample as it is being chewed before
being swallowed or expectorated.
0.5% NaCl solution
5.0
Bitter
The amount of bitter taste detected from
the sample as it is being chewed before
being swallowed or expectorated.
0.8% caffeine solution
5.0
Umami
Flavor associated with monosodium
glutamate.
0.5% monosodium glutamate
solution
7.6
Serumy/metallic
Flavor associated with blood or rare meat
Rare beef
3.0
Cooked chicken
Flavor associated with cooked white
chicken meat
Boiled chicken breast
8.0
Fatty
Flavor associated with animal fat
Chicken fat
8.0
Fishy
Flavor associated with cooked fish
Boiled fish
11.0
Rancid
Flavor associated with rancid/oxidized oil
Oxidized oil
6.0
APPENDIX U: BALLOT FOR COOKED GROUND CHICKEN
APPENDIX V: SENSORY ATTRIBUTES FOR FRIED, BATTERED, AND
BREADED CHICKEN PATTIES
Sensory attributes and its description and anchored references, and their position on the 15 cm
line scale as identified for deep-fried, battered, and breaded chicken patties.
Attribute
Description
Reference/Brand/Preparation
Color
Color of the top surface of the sample
2
(0 – yellow, 15 – dark brown)
CMP warm-up sample
JBP warm-up sample
Position
1
(cm)
5.7
10.4
Evenness of
color
Evenness of the color of the top
surface of the sample
(0 – even, 15 – not even/blotchy)2
CMP warm-up sample
JBP warm-up sample
7.9
8.3
Greasiness
of surface
The amount of grease that is
perceived from looking at the top
surface of the sample
2
(0 – not greasy, 15 – greasy)
CMP warm-up sample
JBP warm-up sample
6.6
7.0
Hardness
The force that is required to bite
through the sample with incisors 3
Cheese/pasteurized American/ 1/2 in
slice
CMP warm-up sample
JBP warm-up sample
Olive/Goya foods®/one giant size
Frankfurter/ Hebrew national®/large,
cooked 5 min/ ½ in slice
Peanuts/ Planters®/cocktail type in
vacuum tin
4.5
The force and noise with which a
product breaks or fractures (rather
than deforms) when chewed with the
3
molar teeth
Defrosted fries/Ore-Ida® Golden
Fries/brought to room temperature
CMP warm-up sample
JBP warm-up sample
Cereal/Quaker® Oatmeal squares
1.2
6.5
8.9
12.7
Moisture
release
The amount of moisture released
during a predetermined number of
3
chews
Carrot/1 inch cubes
Mushroom/button/quartered
JBP warm-up sample
Snap beans/1/2 inch pieces
CMP warm-up sample
2.0
4.0
4.0
7.0
10.0
Oily mouth
coating
The amount of oily coating that is
perceived in the mouth cavity after
the sample has been swallowed or
2
expectorated
JBP warm-up sample
CMP warm-up sample
Cold fries/Ore-Ida® Golden Fries/deepfried, cooled to room temperature
3.7
4.1
6.0
Salty
The amount of salty taste detected
from the sample as it is being
chewed before being swallowed or
expectorated 2
JBP warm-up sample
CMP warm-up sample
0.5% NaCl solution
1.3
2.2
5.0
Sweet
The amount of sweet taste detected
from the sample as it is being
chewed before being swallowed or
expectorated 2
JBP warm-up sample
CMP warm-up sample
5% sucrose solution
0.2
1.0
5.0
Sour
The amount of sour taste detected
CMP warm-up sample
0.1
Crunchiness
4.8
5.4
6.0
7.0
9.5
from the sample as it is being
chewed before being swallowed or
expectorated 2
JBP warm-up sample
0.8% citric acid solution
0.2
5.0
Bitter
The amount of bitter taste detected
from the sample as it is being
chewed before being swallowed or
2
expectorated
CMP warm-up sample
JBP warm-up sample
0.8% caffeine solution
0.0
0.0
5.0
Umami
The amount of umami taste detected
from the sample as it is being
chewed before being swallowed or
expectorated 2
JBP warm-up sample
CMP warm-up sample
0.5% monosodium glutamate solution
0.0
0.6
7.0
Chicken fat
flavor
The amount of chicken fat flavor
detected from the sample as it is
being chewed before being
2
swallowed or expectorated
CMP warm-up sample
JBP warm-up sample
Render chicken fat
3.7
3.9
9.6
Chickeny
The amount of chicken flavor
detected from the sample as it is
being chewed before being
swallowed or expectorated 2
CMP warm-up sample
JBP warm-up sample
Chicken breast/cooked in bag in boiling
water for 15 min
5.1
6.4
10.1
Cooking oil
flavor
The amount of cooking oil flavor
detected from the sample as it is
being chewed before being
2
swallowed or expectorated
CMP warm-up sample
JBP warm-up sample
Used frying oil/Canola oil with added
dimethylpolysiloxane
2.3
4.9
9.7
CMP warm-up sample
JBP warm-up sample
5% whey solution
0.8
1.1
9.7
Whey flavor
The amount of cooking oil flavor
detected from the sample as it is
being chewed before being
swallowed or expectorated 2
1
Position on 15-cm line scale
2
Generated by descriptive analysis panel
3
Adapted from Meilgaard et al. (1999)
APPENDIX W: BALLOT FOR CRACKERMEAL-COATED PATTIES
APPENDIX X: BALLOT FOR JAPANESE BREADCRUMB-COATED PATTIES
APPENDIX Y: SAMPLING CODE AND ORDER FOR CRACKERMEALCOATED PATTIES
Code
Session 1
106
156
286
328
336
445
Session 2
524
607
686
723
725
768
Replication
pH level
WPI concentration
(% w/w)
2
2
2
1
1
2
3
3
2
2
3
2
0
5
2.5
10
0
10
2
2
1
2
1
1
2
3
control
control
3
3
0
2.5
control
control
5
2.5
2
1
1
2
1
1
2
2
3
3
2
2
5
2.5
10
10
5
0
Session 3
826
868
876
927
929
972
APPENDIX Z: SAMPLING CODE AND ORDER FOR JAPANESE
BREADCRUMB-COATED PATTIES
Code
Replication
pH level
WPI concentration
(% w/w)
Session 1
112
167
221
233
254
2
2
1
1
1
3
3
3
3
2
10
5
5
0
10
1
2
2
2
2
1
8
8
2
control
3
2
5
2.5
10
1
1
2
1
2
1
3
8
2
control
8
2
10
10
5
2
2
1
3
8
3
2.5
10
2.5
2
1
1
2
2
1
8
8
8
2
2
2
0
0
2.5
2.5
0
2.5
Session 2
300
377
389
415
423
471
Session 3
473
519
562
653
761
783
Session 4
808
823
828
0
5
5
0
Session 5
886
945
951
962
978
984
TAD
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Date: 2008.06.04 11:40:51 -04'00'