EVALUATION OF SUGARCANE JUICE QUALITY
AS INFLUENCED BY CANE TREATMENT
AND SEPARN CONCENTRATIONS
By
Ghada A/Rahman A/Razig El Sheikh
B.Sc. (Science)
Department of Rural Education, Extension and Development
University of Ahfad
A thesis submitted to University of Khartoum in partial fulfilment for
the requirement of the degree of Master of Science in Agriculture
Supervisor
Prof. Elfadil Elfadl Babiker
Department of Food Science and Technology
Faculty of Agriculture
University of Khartoum
January 2009
i
DEDICATION
To my husband
To my parents
To my sisters and brothers
To Abbass family
To those whom I will never forget
ii
ACKNOWLEDGEMENT
First I thank Allah with his wills this work completed.
Thank my family, who were ready to render much assistance, I
asked for to complete this work.
Many people made great efforts and support me during study.
My sincere gratitude to:
*
The study supervisor, Professor Elfadil Elfadl Babiker, Faculty
of Agriculture, University of Khartoum, for extending research
works and to the final writings of the thesis, that allowed this
study to reach conclusion.
*
Syd/Mohamed Ahmed Fadlased, Kenana Human Resource
General Manager.
*
Dr. Elbashir Ali Hamad, Former Kenana Ex-Training Manager,
for invaluable guidance throughout the study which gave
confidence to execute it.
*
Syd/Ibrahim Mustafa, Former Kenana Sugar Factory Manager.
*
Dr. Makawi Awad A/Rahman, Kenana Sugarcane Researcher,
for extending research works to cover essential areas and
helping the final writing of the thesis.
*
Dr.Kamal Sliman, Food engineering and Technology,
University of Gezira, for follow-up and thesis revision.
*
Dr. Ibrahim Doka, Kenana Sugarcane Researcher, for research
analysis.
*
Syd/Dafalla Hashim, Kenana Quality Control Manager, for
providing research's requirements.
*
Kenana Sugarcane Research and Development Department
*
Kenana Quality Control Department.
*
My colleagues in Kenana Training Centre.
iii
LIST OF CONTENTS
DEDICATION
ACKNOWLEDGEMENT
LIST OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
ABSTRACT
ARABIC ABSTRACT
CHAPTER ONE: INTRODUCTION
CHAPTER TWO: LIETERATURE REVIEW
2.1. Sugarcane and Cane Juice Composition
2.1.1 Sugarcane
2.1.2 Cane Juice from the Mills
2.2 Characteristics of Cane Juice
2.3 Chemistry of coloured Non-sugars
2.4 Coloured non-sugar originally existing in sugarcane
2.4.1 Chlorophyll
2.4.2 Anthocyanin
2.4.3 Saccharetin
2.4.4 Tannins
2.5 None coluored in cane which may develop colour
2.5.1 Polyphenols
2.5.2 Amino compounds
2.6 Coloured non-sugars from sugar decomposition products
2.6.1 Caramel
2.7 Sugar decomposition products
2.8 Reaction products between reducing sugars and amino compounds
2.9 Physical and chemical properties of coloured non-sugars
2.9.1 Inversion
2.9.2 Reaction with phenols
2.9.3 Reaction with amines
2.9.4 Reaction with reducing agents
2.9.5 Reactions with oxidizing agents
2.9.6 Reaction with aldehydes
2.9.7 Effect of pH on colour
2.10 Colour developments
2.10.1 Raw sugar colour
2.10.2 Coluor development in processing raw cane sugar
2.10.3 Colour development in white sugar
2.11 Removal of colour by precipitate and adsorbents
2.11.1 Lime
2.11.2 Phosphoric acid
2.11.3 Flock conditioners
2.12 Definition
2.12.1 Primary juice (crushed juice)
2.12.2 Secondary juice (mixed juice)
iv
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2.12.3 Clarified juice
2.12.4 Imbibitions
2.12.5 pH
2.12.6 The sucrose (POL)
2,12,7 The dry matter content (brix)
2.12.8 Reducing sugar (R.S)
2.12.9 Purity
2.12.10 Turbidity
2.12.11 Colour
CHAPTER THREE: MATERIALS AND METHODS
3.1 Materials
3.2 Methods
3.2.1
Determination of pH
3.2.2
Determination of the sucrose content (pol)
3.2.3
Determination the dry matter content (BRIX)
3.2.4
Determination of reducing sugar (RS)
3.2.5
Determination of the colour value
3.2.6
Turbidity determination
3.2.7
Tannin determination
3.2.8
Total polyphenols determination
3.2.9
Saparan dose experiment
3.3 Statistical analysis
CHAPTER FOUR: RESULTS AND DICUSSIONS
4.1 Effect of milling on the proximate composition (%) of green and burned
cane
4.2 Effect of processing on quality parameters of burned cane juice
4.3 Colouring substances in the raw materials and processed
4.4 Effect of different doses of separan on juice quality parameter
4.5 Effect of different doses of separan on polyphenols and tannins levels
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion
5.2 Recommendations
REFERENCES
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LIST OF TABLES
Table
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Page
Effect of milling on the proximate composition (%) of
green and burned cane
34
Effect of processing on quality parameter of burned cane
juice
37
Colouring substances in the raw materials and processed
39
4
5
Effect of different doses of Separan on juice quality
parameters
42
Effect of different doses of Separan on polyphenols and
tannins levels
45
vi
LIST OF FIGURES
Figure
Page
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Cane samples
23
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Sedimentation study apparatus in operation
31
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Sample of green and burned cane
35
vii
EVALUATION OF SUGARCANE JUICE QUALITY
AS INFLUENCED BY CANE TREATMENT
AND SEPARN CONCENTRATIONS
M.Sc. (Thesis)
By
Ghada A/Rahman A/Razig El Sheikh
Abstract: The study is conducted to evaluate juice quality
parameters ((percentage of cane )pol, brix, … etc) and the level
of colouring materials in crushed cane (green or burned) crushed,
mixed and clarified juice and to evaluate the effect of low doses
of separan on juice quality and colour. The range of pol (sucrose)
for juice treated 10.18 to 15.75%, brix ranged from 12.86 to
20.93%, purity ranged from 82.18 to 95.18%, pH ranged from
5.40 to 7.60, reducing sugar was ranged from 0.58 to 1.10%,
turbidity was ranged from 4.96 to 9.60 NTU(nephlo turbidity
unit) and colour was ranged from 2600 to 14692 ICUMCA. The
study revealed that both the green cane and clarified juices and
lime (temperature treatment) had significant (P≤0.05) higher
colour readings compared to that of the burned cane, mixed and
crushed juice. Likewise, the highest concentrations of colouring
materials (polyphenols and tannins) were recorded in green
0.216, crushed 1.189 and final molasses 0.218. Addition of
separan at very low concentration (0.015 ppm) was observed to
reduce the colouring matter compared to the standard (3 ppm)
concentration applied. The results obtained indicated that the
juice colouring matter (polyphenols and tannins) levels had been
greatly reduced during treatment.
viii
‫ﺘﻘﻴﻴﻡ ﺠﻭﺩﺓ ﻋﺼﻴﺭ ﺍﻟﻘﺼﺏ ﺍﻟﻤﻌﺎﻤل ﺒﺘﺭﺍﻜﻴﺯ ﺍﻟﺴﺒﺭﺍﻥ‬
‫)ﺃﻁﺭﻭﺤﺔ ﻤﺎﺠﺴﺘﻴﺭ(‬
‫ﻏﺎﺩﺓ ﻋﺒﺩ ﺍﻟﺭﺤﻤﻥ ﻋﺒﺩ ﺍﻟﺭﺍﺯﻕ‬
‫ﺍﻟﻤﺴﺘﺨﻠﺹ‪ :‬ﺃﺠﺭﻴﺕ ﻫﺫﻩ ﺍﻟﺩﺭﺍﺴﺔ ﻟﺘﻘﻴﻴﻡ ﺍﻟﻌﺼﻴﺭ ﻤـﻥ ﺤﻴـﺙ ﺍﻟﺒـﻭل)ﻨـﺴﺒﻪ‬
‫ﺍﻟﺴﻜﺭﻴﺎﺕ( ﻭﺍﻟﺒﺭﻜﺱ)ﻨﺴﺒﻪ ﺍﻟﻤﻭﺍﺩ ﺍﻟﺼﻠﺒﻪ ( ﻭﻏﻴﺭﻫﺎ ﻤﻥ ﺍﻟﺘﺤﺎﻟﻴل ﻭﺃﻴﻀﹰﺎ ﺍﻟﻤﻭﺍﺩ‬
‫ﺍﻟﻠﻭﻨﻴﺔ ﻓﻲ ﻋﺼﻴﺭ ﺍﻟﻘﺼﺏ ﺍﻷﺨﻀﺭ ﻭﺍﻟﻤﺤﺭﻭﻕ ﻭﺍﻟﻌﺼﻴﺭ ﺍﻷﻭﻟـﻲ ﻟﻠﻁـﻭﺍﺤﻴﻥ‬
‫ﻭﺍﻟﻤﺨﻠﻭﻁ ﻭﺍﻟﻨﻘﻲ‪ ،‬ﻭﺘﻘﻴﻴﻡ ﺍﺜﺭ ﺍﻗل ﺠﺭﻋﺔ ﻤﻥ ﺍﻟﺴﺒﺭﺍﻥ ﻋﻠـﻲ ﺠـﻭﺩﺓ ﺍﻟﻌـﺼﻴﺭ‬
‫ﻭﺍﻟﻠﻭﻥ‪ .‬ﺍﻟﺘﺤﺎﻟﻴل ﻟﻌﺼﻴﺭ ﺍﻟﻘﺼﺏ ﺃﻭﺠﺩ ﺍﻟﺒﻭل ﻓـﻲ ﻤـﺩﻱ ﻤـﻥ ‪ 10.18‬ﺇﻟـﻲ‬
‫‪ ،%15.75‬ﺒﺭﻜﺱ ‪ 12.86‬ﺇﻟﻲ ‪ ،%20.93‬ﺩﺭﺠﺔ ﺍﻟﻨﻘﺎﺀ ‪ 82.18‬ﺇﻟﻲ ‪،%95.18‬‬
‫ﺍﻟﻬﻴﺩﺭﻭﺠﻴﻥ ﺍﻴﻭﻥ ﻤﻥ ‪ 5.40‬ﺇﻟﻲ ‪،7.60‬ﺍﻟﺴﻜﺭ ﺍﻟﻤﺨﺘﺯل ﻤﻥ ‪ .58‬ﺇﻟﻲ ‪،%1.10‬‬
‫ﻭﺍﻟﻠـﻭﻥ ﻤـﻥ ‪ 2600‬ﺇﻟـﻲ ‪ NTD 14692‬ﺍﻟﻌﻜﺎﺭﺓ ﻤﻥ ‪ 4.94‬ﺇﻟـﻲ ‪9.60‬‬
‫‪ICUMCA.‬‬
‫ﺍﻟﻨﺘﺎﺌﺞ ﺘﻭﻀﺢ ﺍﻟﻌﻼﻗﺔ ﺒﻴﻥ ﺍﻟﻘﺼﺏ ﺍﻷﺨﻀﺭ ﻭﺍﻟﻌﺼﻴﺭ ﺍﻟﻨﻘﻲ ﺤﻴﺙ ﻭﺠﺩ‬
‫ﺃﻨﻬﻤﺎ ﻴﺤﺘﻭﻴﺎﻥ ﻋﻠﻰ ﻨﺴﺒﺔ ﻋﺎﻟﻴﺔ ﻤﻥ ﻗﺭﺍﺀﺓ ﺍﻟﻠﻭﻥ ﻤﻘﺎﺭﻨـﺔ ﺒﺎﻟﻘـﺼﺏ ﺍﻟﻤﺤـﺭﻭﻕ‬
‫ﻭﺍﻟﻌﺼﻴﺭ ﺍﻟﻤﺨﻠﻭﻁ ﻭﺍﻟﻌﺼﻴﺭ ﺍﻷﻭﻟﻲ‪.‬‬
‫ﻋﻠﻰ ﻨﻔﺱ ﺍﻟﻨﻤﻁ ﻨﺠﺩ ﺃﻋﻠﻰ ﺘﺭﻜﻴﺯ ﻟﻠﻤـﻭﺍﺩ ﺍﻟﻠﻭﻨﻴـﺔ ﺍﻟﺒـﻭﻟﻲ ﻓﻴﻨـﻭﻻﺕ‬
‫ﻭﺍﻟﺘﺎﻨﻴﻨﻴﺎﺕ ﺴﺠﻠﺕ ﻓﻲ ﺍﻟﻘﺼﺏ ﺍﻷﺨﻀﺭ )‪ (0.216‬ﻭﺍﻟﻌﺼﻴﺭ ﺍﻷﻭﻟـﻲ )‪(1.189‬‬
‫ﻭﺍﻟﻤﻭﻻﺱ ﺍﻟﻨﻬﺎﺌﻲ )‪ .(0.218‬ﺍﻟﺩﺭﺍﺴﺔ ﺘﺅﻜﺩ ﺃﻥ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻤﻠﻭﻨﺔ ﻟﻠﻌﺼﻴﺭ ﺘﻨﺨﻔﺽ‬
‫ﺘﺩﺭﻴﺠﻴﹰﺎ ﺍﺜﻨﺎﺀ ﺍﻟﻤﻌﺎﻤﻼﺕ‪.‬‬
‫ﻨﺘﻴﺠﺔ ﺍﻀﺎﻓﺔ ﺍﻟﺴﺒﺭﺍﻥ ﻋﻨﺩ ﺃﺩﻨﻲ ﺘﺭﻜﻴﺯ )‪ (0.015 ppm‬ﻤﻘﺎﺭﻨﺔ ﺒﺎﻟﻤﻘﻴﺎﺱ‬
‫ﺍﻟﻤﻌﻴﺎﺭﻱ )‪ (3 ppm‬ﺍﻟﻤﺴﺘﺨﺩﻡ ﻓﻲ ﺍﻟﻤﺼﻨﻊ ﻗﻠﻠﺕ ﻤﻥ ﻤﺴﺘﻭﻱ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻠﻭﻨﻴﺔ ﻓﻲ‬
‫ﺍﻟﺒﻭﻟﻲ ﻓﻴﻨﻭﻻﺕ ﻭﺍﻟﺘﺎﻨﻴﻨﺎﺕ ﻭﺼﺎﺤﺏ ﺫﻟﻙ ﺠﻭﺩﺓ ﻋﺎﻟﻴﺔ ﻤﻥ ﻨﻘﺎﺀ ﺍﻟﻌﺼﻴﺭ ﻭﻗـﺭﺍﺀﺓ‬
‫ﺃﻗل ﻟﻠﻭﻥ‪.‬‬
‫‪ix‬‬
x
CHAPTER ONE
INTRODUCTION
Colour of the sugar crystals is an important factor that
determines its value in the market and acceptability for various uses.
Formation of colour takes place in the juice syrup, and final products
because of caramalisation and melunoidius formation. Besides, these
juices contain a series of natural colouring compounds and other
constituents such as polyphenols, amino acids, etc. All these
constituents can not be eliminated during the process of clarification
and generate colour during the post-clarification process up to the raw
cane.
Mathur (1993) reported that polyphenols formed brown iron
complexes where as others generate colour by polymerization due to
the effect of high temperatures used in the processing operations.
Although these colouring factors and constituents can not be
eliminated during processing, efforts can be made to reduce the
formation of brown iron complexes and polymerization of colouring
matters by suitable measures.
Colouring matters are found in sugarcane, as in all growing
plants. In milling, they are extracted with the cane juice and constitute
a portion of the non-sugars to be contended with in subsequent
processing of the sugar. Somasekhar (2001) stated that in addition,
other colouring materials are formed in the manufacturing and
refining operations as a result of chemical reactions between certain
non-sugar materials present or developed during the process. The
presence of such materials depend on type of cane, soil, and growing
1
conditions, geographical area, and the milling and refining process
employed.
The substances responsible for the colour of the sugar are
normally classified as non-sugar impurities. The production of both
raw and refined sugars and the removal of the coloured impurities
become extremely important; particularly in view of the increasing
demands for exceptionally high quality white refined sugar
(Srivastava, 2006).
Objectives:
The present study was conducted to meet the following objectives:
*
To determine parameters that characterizes the sugar juice from
the initial stage to the clarification stage.
*
To study the effect of using different concentrations of Separan
on the colour of the juice.
*
To compare different parameters of green and burned cane
juice.
2
CHAPTER TWO
LITERATURE REVIEW
2.1 Sugarcane and cane juice composition:
2.1.1 Sugarcane:
Basically the sugarcane stalk consists of the outer rind of thick
walled cells and the softer parenchyma tissue and vascular bondless
within. The rind and vascular bundles constitute the fibrous portion of
the fibre whilst the parenchyma constitutes the pith. The materials
together make up the fibre of the cane as determined by analytical
methods (George et al., 1997).
The parenchyma cells contain sugar rich juice and since these
cells are easily ruptured the is liquid from these cells which is first
expressed when the cane stalk is crushed. This is then the origin of
the high purity first expressed juice. The remaining juice is found in
the relatively sturdy vascular bundles carrying nutrients between the
roots and leaves of the plant. The juice is dilute, of low purity and of
variable composition. It is difficult to express, hence the last juice
expressed is always of low purity.
Also, non-sugars from the parenchyma cells are of such a nature
that they are easily removed during clarification whereas non-sugars
in the juice from the vascular bundles are not.
The percentage of sugar (commonly called "polarization") in
the cane varies from 8 to 16% and depends to a great extent on the
variety of cane, its maturity, the condition of the soil, the climate and
agricultural practices followed (Blackburn, 1984).
3
2.1.2 Cane juice from the mills:
Cane juice is an easily foaming turbid liquid, ranging in colour
from light grey to dark green. Fresh cane juice is slightly acidic and
because of the colloidal matter content is not easily filterable. The
green colouration is due to a combination of dyes from cane ferric
salts in the juice. Ferric salts in turn react with tannins in the juice
producing the green colouration. Chen et al. (1993) stated that cane
Juice contains sucrose, reducing sugars, inorganic-salts, organic- salts,
organic acids, pectin, gums, proteins, dyes, tannin and iron
compounds in solution in add rife it contains bagasse, sand, clay,
chlorophyll, wax, albumen, air and soil in suspension.
2.2 Characteristics of cane juice:
Cane juice has an acidic reaction with the pH range 4.9 to 5.5.
The cane juice is opaque owing to the presence of silica and colloidal
substances such as waxes, proteins, gums, starch and they impart
turbidity to the juice. These colloids do not settle ordinarily unless
conditions are altered. The application of heat or addition of chemicals
(electrolytes) brings about flocculation or coagulation (Perry's, 1988).
Finar (1998) stated that the rind cells of sugarcane stalks
contain a mixture of two colouring matters, the chlorophyll and the
anthocyanin. The fibre of the cane contains saccharetin and the tops
and buds of the plant contain tannins and several other colouring
matters but very little are known about them. These pass with the juice
on extraction.
2.3 Chemistry of coloured non-sugars:
The general nature of the organic non-sugar substances
responsible for the colouring in sugarcane and in raw cane juice has
been reported in the literature to some degree during the past several
4
decades. Kul (1989) discussed that the colour of the cane juice may
have two origins:
(a)
Colouring matters from the cane itself. This may have four
origins:
(1) Chlorophyll, (2) anthocyanin, (3) saccharetin and (4)
tannins.
(b)
Chemical decomposition. This may have three origins:
(1) Colouration of the juice due to the decomposition of its
constituents by the action of lime or of heat or of both. (2)
colouration of the juice due to the presence of soluble iron salt
(ferric) from equipment, because of reaction with polyphenols,
and (3) colouration of the juice due to reaction of non-sugars
with other substances.
2.4 Coloured non-sugar originally existing in sugarcane:
While the literature refers to the colour substances in cane by a
variety of names, there appear to be about six principal types, i.e.
chlorophylls, xanthophylls, carotenes, sachharetin, tannins and
Anthcyanins.
The colour produced by the pigments is dependent upon the
hydrogen ion concentration of the cell sap. When the sap is acidic the
colour is red and when it is alkaline the colour is blue (Srivastava,
2006).
Chlorophyll, carotene and saccharetin are harmless colouring
matter in white sugar manufacturing. They are insoluble in sugar
solutions and therefore are easily removed by clarification of the juice
(John, 1988).
5
2.4.1 Chlorophyll:
This is present in every green plant. It is a harmless colouring
matter in white sugar manufacture since it does not react with lime aid
and acids have no reaction with it. It is insoluble in water and in sugar
solutions but soluble in alcohol, ether... etc. It is in colloidal nature
and exists as suspension in cane juice, removed by filtration after
clarification of the juice is done without affecting the colour of the
sugar subsequently produced.
2.4.2 Anthocyanin:
This is present only in certain dark varieties of cane. Unlike
chlorophyll, it is readily soluble in water and cane juice and also
during the process of milling, it passes almost completely into the
cane juice giving a dark colouration to the juice. The purple colour of
anthocyanin solution is changed into dark green by the addition of
lime. The pigment, if present in small amounts, is precipitated by a
small amount of calcium hydroxide (lime) used for defecation. If the
pigment is of the amount normally found in dark varieties, then the
quantity of lime used in defecation is insufficient for the elimination
of the colouring bodies. More lime has to be added to precipitate these
pigments completely (John, 1988).
2.4.3 Saccharetin:
The saccharetin is found impregnated in the fiber of the cane.
This colouring substance cannot be extracted with water or sugar
solution from the fiber, but when these media are rendered alkaline
with calcium hydroxide (lime) or with any other alkaline body, the
hitherto colourless saccharetin becomes yellow and extracted by the
liquid.
In the raw juice, there are fine particles of bagasse in
6
suspension and when lime is added the yellow pigment is extracted. It
is, therefore, important to remove as much of 'cush-cush' (fine
bagasse) from juice as possible, before the juice is limed so that the
saccharetin is prevented from entering the clarified juice. Saccharetin
is comparatively a harmless pigment, as it becomes colourless again in
neutral or acidic media below pH 7.0 (John, 1988).
2.4.4 Tannins:
These bodies are located in the actively vegetative portion of
the cells, especially of the 'tops' and the buds. It is soluble in juice. It
is green but when reacts with iron salts present in the juice it becomes
dark in colour. On heating it decomposes with the formation of
catechol and combines with alkalis to form protocatechnic acid.
Heating in acid solution produces pholobaphene and protocatechnic
acid which is similar to saccharetin. John (1988) stated that with
tannin is normally removed by the addition of Saparan to the juice in
the clarification stage.Saparan enhances the formation of flogs
containing tannins and those eventually settle at the bottom of the
clarifier. The flocks are then pumped out to a rotary vacuum filter.
2.5 None coloured in cane which may develop colour
Numerous non sugar materials have been described in the
literature as being present in the cane in colourless form but when
combined or reacted with other substances form colouring matter.
Probably the most significant of such materials can be classified in
two general groups, i.e. polyphenols and amino compounds (Saharia,
1997).
7
2.5.1 Polyphenols:
Polyphenols react with iron (ferric) and oxygen particularly in
alkaline solutions and form dark coloured products. In the raw juice it
is attached to the bagasse particles and can therefore be separated
during clarification.
2.5.2 Amino compounds:
Cane juice contains nitrogenous bodies such as albuminods,
ammonia, amino acids and amides. These compounds can react with
reducing sugars and form coloured compounds.
2.6 Coloured non-sugars from sugar decomposition products:
Rein et al. (2007) stated that with the processing of cane juices,
both the sugars and non-sugars materials are subjected to heat, varying
pH, air, iron "from equipment", added chemical compounds "such as
lime", etc. All these factors have a distinct effect on the development
of colour. Some of this colour may be developed from the chemical
reaction with non-sugars component of the cane juice, and some may
occur as a result of decomposition products formed. These coluored
compounds vary in type and include products from caramalisation,
decomposition of the sugars and the products subsequently formed
with other compounds. Because these reactions are so inter-related, it
is some what difficult to make any separation into particular groups.
For example, sucrose solutions invert when becoming acid, the
reducing sugars formed decompose with heat and in alkaline
solutions, reactions occur with other non-sugar materials such as poly
phenols, amino compounds, etc. The nature and extent of these
various reactions and the final colour compounds formed are
dependent upon the conditions involved.
8
2.6.1 Caramel:
When heated sugar juice temperature is about 200C°a dark
colored material is formed. This is apparently due to hydration and
condensation reactions of the heated sugars. Caramels are formed
from sucrose as well as glucose and fructose. The composition of the
caramel depends upon temperature, pH and time of heating.
2.7 Sugar decomposition products:
When sucrose in solution is subjected to high temperatures and
acid conditions it hydrolyzes to form the reducing sugars, D-glucose
and D-fructose. With prolonged heating and under strongly alkaline
conditions, these hexoses decompose.
The resulting products are
brown colored and acids, causing further inversion of sucrose.
However, in strongly alkaline solutions, dark coloured products
are formed from decomposition of the reducing sugars.
At low
temperature the colour formation is much less than at high
temperature. In the later case, the brown reaction products have the
disadvantage of breaking up into acidic secondary products permitting
further inversion (Hunsigi, 1993).
2.8 Reaction products between reducing sugars and amino
compounds:
Mathur (1993) stated that amino acids react or condense with
dextrose dehydration products such as hydroxymethyl, furfural,
laevulin acid and hydroxymethyl fluoric acid to form coluored bodies
and this reaction is not prevented by the neutralization of the amino
acids.
9
The colour development is distinguishable in heated solutions
of sugar but is much more apparent when amino compounds, such as
asparagines or aspartic acid are present with reducing sugars. The
importance of those compounds in cane products will only appear to
be pronounced where large amounts of reducing sugars are formed
and subsequently destroyed.
2.9 Physical and chemical properties of coloured non-sugars:
2.9.1 Inversion:
Joachim et al. (2000) stated that when sucrose is inverted, by
means of an acid or enzyme, the molecule is broken up to give glucose
and fructose.
C12H22O11 + H2O
Sucrose
water
C6H12O6 + C6H12O6
glucose
fructose
Inverted sugars
This reaction is known as hydrolysis or inversion and proceeds
at varying rates depending on conditions such as temperature, time
and pH. These two reducing sugars develop colour when subjected to
heat and alkaline conditions. If such conditions are extreme the
reducing sugars will be destroyed and various reaction products are
formed. These reaction products unite readily with other compounds
that may be present or occur in process, and the resulting substances
are often the source of the colouring materials found in cane juice and
raw sugar products.
2.9.2 Reaction with phenols:
Very strong colour reactions are obtained between sugars and
various phenols, when concentrated mineral acids are present. This is
10
due to the combination of the sugar decomposition products, such as
furfural, with the condensation products from the phenol derivatives
(Joachim et al., 2000).
Reducing sugars combine with different polyphenols to form
amorphous condensation products. An example of such a reaction
with a rabinose is as follows:
C5H10O5 + C6H10O6
C11H14O6
Arabinose
Arabinose Resorcinol
Resorcinol
+
H2O
Water
The colour obtained with different sugars may be found upon
examination of the decomposition products obtained when heating in
acid solutions. It is mentioned that true glycoside of various phenols
and polyphenols are found in nature.
2.9.3 Reaction with amines:
Sugars combine readily with amino compounds such as the
aromatic amines, aniline, xylonite, and diphenylamine, in the presence
of concentrated hydrochloric acid.
The colour reaction is not as
significant as in the case of polyphenols. They result from the uniting
of the sugar decomposition products, furfural, methyl furfural, and
hydroxymethyl furfural with the amines. =Examples of the reaction in
the case of glucose are as follows:
H-C = O + N2NC6H5
H-C = N – C6H5 +
(HCOH)4
( HCOH)4
CH2OH
CH2OH
Glucose
Aniline
Glucose Aniline
11
H2O
water
Various colours are obtained in such reactions. Glucose gives a
green colour, fructose a pale yellow, etc. Reducing sugars also react
easily with other nitrogen compounds such as phenyl hydrazine (in the
hydrazones osazone reactions), hydroxyl-amine (oxide reaction) and
urea "uried reaction", etc (Joachim et al., 2000).
2.9.4 Reaction with reducing agents:
Reducing agents change the reducing sugars to alcohols. For
example, sodium amalgam reduces mannose to the alcohol mannitol.
When maintained slightly acidic sorbet is formed.
2.9.5 Reactions with oxidizing agents:
Oxidizing agents such as nitric acid change reducing sugars into
dibasic acids. Ketoses sugars decompose into acids such as oxalic and
formic acids. With weak oxidizing agents, monobasic acids are
obtained. Some of these acids react with ferric salt to form dark
coluored compounds (Steindl, 2005).
2.9.6 Reaction with aldehydes:
Reducing sugars react with various aldehydes, such as
formaldehyde,
benzaldehyde,
furfural,
etc.
to
form
various
condensation products. Some of these compounds are unstable and
decompose into different acids. Coluored compounds can result from
any number of these reactions.
2.9.7 Effect of pH on colour:
It is well recognized that the colour of sugar products is greatly
dependent upon the pH of the sugar solution. In general, the colour is
lighter in acid solutions than in alkaline solutions. This has been
observed in many decolourization processes. It has also been noted in
12
investigation on method of colour measurement. In the latter case, the
practice often used is of adjusting solutions to a standard pH of 7 prior
to colour determination in order to avoid the variable effect caused by
different pH values (Griffiths, 1991).
2.10. Colour developments:
The processing of sugar is generally carried out in two stages,
the crystallization of the clarified, concentrated cane juice in the raw
sugar and then refining of the raw sugar to produce white sugar. In
clarifying the raw sugar juice, heat and lime increase the colour due to
decomposition of the reducing sugars. The presence of iron from
equipment tends to increase the colour further because of reaction
with polyphenols. In the evaporation and crystallization steps colour
may be formed from caramalisation and decomposition products due
to overheating discussed by (Hugot, 1990).
Care is needed in the process to avoid colour formation, as far
as possible. Various steps are usually adopted to minimize the
formation of colour. The solutions are maintained close to pH 7 and
excessive temperature is avoided. Clarification with lime, phosphoric
acid and separan and decolourization with bone char, or comparable
methods, are used to remove colour. In the latter cases temperature
and pH are carefully controlled to prevent additional colour formation.
Zerban (2000) discussed colour development in processing of
raw cane juice at one length. He pointed out the colour formation in
liming raw cane juice and the general practice of not adding any more
lime than necessary to secure a good precipitate. He stated that most
of the colouring matter formed from the reducing sugars is removed
with the precipitate but the clarified juice may be darker than the raw
13
juice due primarily to polyphenol- iron compounds. If an excess of
lime is used, neutralization is necessary by means of carbonation or
sulphitation and the precipitates formed strongly adsorb colour. In
regard to colour changes during evaporation and crystallization of the
juice, the colour development is largely due to caramalisation and
Melonoids resulting from heating of the juice. Dissolving of iron also
tends to increase the colour.
From the preceding it is evident that cane juices develop colour
in processing. The extent of darkening depending upon the nature of
the juice and the conditions of processing. It is apparent that excessive
heat and alkalinity must be avoided to prevent excessive colour
development. Juice Colour increased by 50 and 100% with trash and
trash plus tops, respectively (Reid and Lionnet 1989).
2.10.1 Raw sugar colour:
In general, most raw or intermediate sugar products have a
yellow amber, or dark reddish brown colour. The amount and nature
of this depends on the type of original colouring matter and the
reactions occurred during processing. The various factors involved
are the source of raw, operation conditions (pH, temperature, etc.);
adsorbents used in processing and other such variables.
The problem of colour in processing raw sugar is referred to
by Halverson and Bollaert (1987). Particular note is made of the
importance of colour quality and mentioned is made of two types of
raw cane sugar, i.e. the grey and the red variety. He pointed out that
the calmed grey raw as more common than red raw. The red colour is
apparently caused by excessive liming.
14
The amount and nature of colour in a raw sugar is of extreme
importance in refining operations. As indicated previously, the colour
is dependent on many factors such as variety of cane, soil conditions,
method of processing, etc. while the total amount of colour will vary
considerably. The general colour character of present day raw is
similar, this is observed from spectrophotometer analysis made by
heath .
2.10.2 Coluor development in processing raw cane sugar:
In general, some factors that are involved in the darkening of
cane juice and raw sugar are also involved
operations.
apply in refining
In the usual processes, the raw sugar is first washed
melted, limed, filtered, and finally decolorized. Decolourization is
accomplished by several means such as phosphoric acid, lime
defecation, carbonation, bone char, decolorizing carbons. It is
undoubtedly apparent that even though one of the primary objectives
of the refining process is to eliminate colour, complete elimination is
not all together practical. Furthermore, the colour formed during the
process so condition must be carefully controlled to avoid excessive
colour development (Hugot, 1986).
2.10.3 Colour development in white sugar:
In general, the white sugars develop colour very slowly if stored
in cool areas (Nelson, 2005). This is to be due expected as the amount
of their low coluored of the non-sugars material.
2.11 Removal of colour by precipitate and adsorbents:
The coluored non-sugars material present in cane juice cans be
removed by various chemical or physical processes. This may involve
15
removal by precipitating agents such as lime, phosphoric acid and
separan that are used in clarification, or adsorbents such as bone char
that are used in purification (Spri, 2001).
While precipitating or adsorbing agents are used to remove
colour, there is danger of forming more colour if they are not used
under proper conditions.
For example, excessive low pH and
temperature can form highly coluored complexes from decomposition
products resulting from destruction of reducing sugars, as previously
indicated. It is therefore essential to maintain conditions that helped
reducing sugars neither formed nor destroyed.
In commercial
practice, every effort is normally made to avoid such conditions that
lead to formation of dark coluored compounds.
2.11.1 Lime:
Lime is the most commonly used material in clarifying cane
juice and is effective in removing insoluble colouring compounds. It
is only slightly soluble in water but sucrose greatly increases its
solubility. Spencer and Meade (2001) described the purification in
cane juice as follow; lime is added in the range of 450-750g CaO per
ton of cane to neutralize the organic acids originally contained in the
juice, they depending upon conditions. This treatment forms a heavy
complex precipitate, In addition to other non-sugar materials such as
waxes and gums, the insoluble coluored compounds, some in
combination with calcium, are precipitated and subsequently removed.
This is a very important process affecting the colour and quality
of raw sugar produced.
16
The method of clarification has a considerable effect on the amount of
soluble lime salts remaining in the clarified juice. Pieter (1995) stated
that with increasing pH, the lime content increases, particularly above
pH8. It is the P2O5 content at the juice has a significant effect, by
lowering the pH due to combination of lime and phosphate.
Excessive lime addition must be avoided to minimize colour
formation and prevent poor quality dark coluored sugars. This is
usually accomplished by controlling the pH at 8.0 – 8.5.
The principle of using lime clarification of raw cane juices is to
precipitate the impurities. The lime combines with both organic and
in organic compounds present to form numerous insoluble calcium
salts. Among the various substances precipitated may be some of the
coluored compounds, although simple lime defecation is not as
effective as phosphate in colour removal.
2.11.2 Phosphoric acid:
For many years the effectiveness of phosphates in clarification
and removal of colour has been recognized. It has been noted that
cane juice having a high P2O5 content, clarify much more readily and
are lighter in colour than those with a low P2O5 content. Usually, the
amount of phosphate in cane juices is quite small, and the precipitate
will be developed when adding phosphoric acid in conjunction with
lime, particularly in the refining process. The particular reactions
involved related to the formation of heavy tri-calcium phosphate (Ca3
(PO4)2) flocculent precipitate which not only occludes the impurities
but also adsorbs much of the colouring matter Pieter (1995).
17
For good clarification it has been stated that the P2O5 content of
the cane juice should be above 300-350ppm. However, some juices
high P2O5 content do not always clarify readily, presumably due to
the excessive colloidal matter present.
The nature of the flock
formation depends greatly on the pH and calcium content of the juice,
although the effect of pH is less above pH7. Additions of P2O5 have
been found to be effective in lowering the colour of juice and or sugar
(Honig, 1995). In the use of phosphoric acid – lime defecation in
refining raw cane sugar, the colouring material removed consists of
most of the colloidal polyphenol iron compounds which give a
greenish brown colour
to the sugar liquor. They found that affination
syrup treated with 0.1% P2O5 as compared to filtered syrup, both at
pH 7.2, gave 20% more colour removal at 459mµ and 28% at 620mµ.
It is obvious of that the degree of colour removal will vary widely,
depending on the character of the raw product being treated.
Halverson and Bollaert (1987) commented on the effectiveness
of phosphoric acid-lime in the defecation of refining syrup. Similar
comment was made by Franken (2007) in pressure filtration of
defecated liquors. the following colour removal on using different
concentration of p2O5.
% P2O5
0
0.1%
0.2%
0.3%
0.5%
% colour removal
0
47%
50%
55%
56%
18
2.11.3 Flock conditioners:
Flock formation can be improved by the use of high molecular
weight water soluble synthetic resins like "Separan". The use of
polymers in the treatment of refrectometer juices has become normal
practice and less expensive than correcting phosphate deficient juice
by the addition of phosphates.
Separan is usually added to the limed juice at the flash tank at a
concentration of 2 to 3 parts per million. However, the method of the
addition of Separan is of great importance for achieving the required,
clarification. Normally a stock solution of 0.5% is prepared, diluted
further to a working solution of 0.05% and fed to the flash tank via a
metering pump.
Certain functional groups in the Separan molecule ionize in
water, to an anionic or cationic molecule on certain conditions such as
the pH of the solution, presence of electrolytes etc.
Segments of the long molecule absorbed on to flock particles
forming a molecular linkage between flock particles. The larger
particles so formed are thus more readily precipitated (Konkani,
1998).
2.12 Definition:
2.12.1 Primary juice (crushed juice):
All juice obtained from cane prior to dilution.
2.12.2 Secondary juice (mixed juice):
Total juice out put of milling tan demes in clouding imbibitions
water.
2.12.3 Clarified juice: The juice obtained as a result of the
clarification process.
19
2.12.4 Imbibitions:
Addition of dilution water or juice to bagasse being milled
(Kenana Technical Manual, 1984).
2.12.5 PH:
Hydrogen-ion concentration by a logarithmic scale (Saharia
1997)
2.12.6 The sucrose (POL):
As defined by ICUMSA (2005) the pol (polarization) of
solution, is defined as the concentration (in grams of solute per 100g
of solution) of a solution of pure sucrose in water having optical
rotation as the sample at the same temperature .For solution
containing only pure sucrose in water, pol is measure of the
concentration of sucrose present, for solution, for solution containing
sucrose and optically active substances,pol represent the algebraic
sum of the rotation of the constituents present.
2.12.7 The dry matter content (brix):
According to ICUMSA methods (1998) the unit, brix is
intended to represent the dry substance content% mass by mass. Chen
et al. (1993) Stated that the brix is the percentage by weight of
sucrose in pure sugar solution. As they mentioned, the percentage of
solid dissolved could be determined by refrectometer either by direct
sugar scale or refractive indices and percentage sucrose.
2.12.8 Reducing sugar (R.S):
Reduced sugars (monosaccharide) are formed by dissociation of
sucrose.
20
Sucrose
∆
Glucose + Fructose
-OH2
Reduced sugar
2.12.9 Purity:
Purity is the percentage of sugar in brix (Chen and Chou, 1993).
Blackburn (1984) mentioned that the purity of a solution containing
sucrose is the proportion by weight of sucrose to all dissolved solids,
expressed a percentage.
Determination of reducing sugar (RS) in practice sucrose is estimated
as POL and solid as brix.
Apparent purity =
Pol %
X 100
Brix %
2.12.10 Turbidity:
The method applies to the determination of turbidity in clarified
juice and it an indicative of the efficiency of the clarification process
(Perry's 1985). The method measures absorbance due to suspended
solid in clarified juice. The turbidity index, (S), is defined as:
S=A/B
Where the effect of light absorption is assumed to be zero.
A=Abs over at 420nµ
B= the cell length in cm
2.13.11 Colour
Colour= brix × factor × absorbance
21
CHAPTER THREE
MATERIALS AND METHODS
3.1 Materials:
Four types of sugarcane juice were collected and analyzed for
different parameters of the juice e.g. pol (sucrose), brix (dry matter),
colour, turbidly, pH, etc. Out of 3 samples, uses collected from the
factory of crushed, mixed, and clarified juice were as the first sample
was collected from milling of clean cane from Labourites of the
Sugarcane Research Department. Sugarcane variety CO997 was used.
The raw materials of all types were carefully prepared before analysis.
Unless otherwise stated all chemicals and reagents used in this study
are of reagent grade. Cane sample collection is shown in Figure 1.
3.2 Methods:
A specific method for detetermination of each parameter for all types
of juice is standardized.
3.2.1 Determination of pH:
Material:
1.
Sugarcane juice.
2.
Distilled water.
Apparatus:
1.
pH-Meter.
2.
Thermometer.
3.
Beaker.
Reagents:
Buffer solution
22
Fig. (1): Cane samples
23
Procedure:
PH-Meter was standardized
with the buffer solution of
different ranges of PH from 7 to 9, Electrode was rinsed with
apportion of the sample to be tested. A beaker was filled by the juice
solution to be tested to depth covering the bulbs of the electrodes. The
temperature of the solution read and the pH-Meter was adjusted for
temperature correction. The system was allowed to be in equilibrium.
The PH of the juice was then read. Electrodes were washed and stored
in distilled water before dales reach reading.
3.2.2 Determination of the sucrose content (Pol):
Material:
1.
Sugarcane juice.
2.
Distilled water.
3.
Poly meter.
Apparatus:
Balance, volumetric flasks 100ml, filter paper (Whatman 19),
polar meter, funnel.
Reagents
Lead Acetate (1.24g/ml).
Procedure:
The sugarcane juice (26.00g) was transferred to 100ml
volumetric flask. Distilled water was added to obtain 100 ml of
solution. Five drops of lead acetate was then added to the solution.
The solution was shacked well, transferred to funnel lined with filter
paper Whatman 19 and filtered. The filter ate was collected, and its
polarization was recorded.
24
3.2.3 Determination of (soluble solid) the dry matter content
(BRIX):
Material:
1.
Sugarcane juice.
2.
Distilled water.
Apparatus:
Refrectometer, calibrated at 20°c and having water-jacketed
prism.
Procedure:
The prism faces of the refrectometer was cleaned and dried. A
drop of distilled water is transferred to the refrectometer prism to
standardize the zero reading. A drop of the juice solution (sugarcane
juice) was transferred to the prism and the reading was recorded, and
corrected (ICUMSA 2005)
3.2.4 Determination of reducing sugar (RS):
Material:
1.
Sugarcane juice.
2.
Distilled water.
Apparatus:
Plate, pipette 5 ml, burette 50ml, flasks 100ml, stand for the
burette, funnel, filter papers.
Reagents:
1) Fehling solution (A): 34,639g of cuso4.5H2O diluted in 500ml
distilled water and filtrate.
Fehling solution (B): 173g of Rochelle or signet.
2) Salt (Na-K-tart rate) and 50g of Na (oH)
distilled water and filtrated.
25
2
diluted to 500ml by
3) Di-sodium oxalate powder
4) Methylene blue indicator.
Procedures:
Twenty five gram of juice was diluted by distilled water to
100ml in a flask.
The solution was shaken well and filtered through a filter paper.
The filtrate was transferred into burette. A mixture of Fehling solution
(A) and (B) was prepared by mixing 5mls of each and few amount of
distilled water in a flask and transferred to a hot plate. Before the
mixture became hot 15ml of the sugar juice in the burette was drained
in to the mixture of Fehling solution. Thereafter, addition of juice was
continued drop wise till the colour changed to tricky.
At this Point two drops of methylene blue were added to
confirm no further change in colour. The volume of the juice filtrate
used was recorded (ICUMSA, 2005).
RS was then calculated using the following formula:
Calculations:
RS =
Fehling Factor
Volume of titration
X 100
Fehling factor (from table)
3.2.5 Determination of the colour value:
Material:
1.
Sugarcane juice.
2.
Distilled water.
Reagent:
1.
One ml hydrochloric acid solution (HCL), 1ml sodium
hydroxide solution (NAOH) for pH correction.
26
Apparatus:
1.
Refrectometer (for measuring brix).
2.
Telemeter (for measuring absorbance) with wave length 420nm.
3.
Buchrer funnel.
4.
Sucking pump.
5.
0.45mm membrane filter paper.
Procedure:
Fifty gram of the juice sample was weighted diluted according
to the need of the experiment and filtered using bunchier funnel with
0.45mm membrane filter. The PH of filtrate was raised to pH 7. Brix
and absorbance degree of the filtrate was recorded using the
refrectometer, and telemeter receptively.
Colour value= Reading (Telemeter) x brix factor = Mau. (ICUMSA
2005)
3.2.6 Turbidity determination
Material:
1.
Clarified juice.
2.
Distilled water.
3.
Juice sample pipes and containers.
Apparatus
Spectrophotometer- suitable for the measurement of absorbance
at 900 nm with matched 1cm cells.
Procedure
The juice sample pipe and the sample containers were flushed
and rinsed with the hot juice immediately before taking the sample.
The hot samples taken were cooled under running cold water to room
temperature (15-25°C). Then the nester tube filled by the sample that
27
to be determined and read, the reading is in, NTU, units (Icumsa,
2005).
3.2.7 Tannin determination:
Apparatus: flask (100) ml.
Test tube, Shaker, Centrifugal, Incubated and conical flask
Material:
Sugarcane juice.
Reagent:
Methanol. 1% HCL. Vanillin.
Procedure:
Quantitative estimation of tannin for each sample was carried
out using modified vanillin –HCL in methanol method as described by
Price et al. (1978). About 0.2g of the juice sample was placed in
a100ml conical flask. Ten millilitres of 1% HCL in methanol (v/v)
were added, shaken for 20min, and centrifuged at 2500rpm for min.
One millilitre of the supernatant was pipetted into a test tube and 5ml
of vanillin –HCL reagent were added. The optical density was read
using Spectrophotometer (JENWAY 6305 UV/3V) at 500nm after 20
minutes incubation at 30ºC. A standard curve was prepared expressing
the results as catching equivalent, i.e. amount of catching (mg per ml)
which gives a colour intensity equivalent to that given by tannins after
correcting for blank.
Calculations:
Tannin concentration was expressed as catching equivalent
(C.E) as follows:
C.E% =
c x 10 x 100
200
28
Where:
C =
10 =
200=
Concentration corresponding to the optical density
Volume of extract (ml)
Sample weight (mg)
3.2.8 Total polyphenols determination:
Material:
1.
Sugarcane juice.
2.
Distilled water.
Apparatus
Test tube, filter papers, constant shaking, funnel and
spectrophotometer.
Regent:
Methanol, 0.1ml Fecl3, 0.1 N HCL and 0.008MK3Fe (CN)6.
Procedure:
Polyphenols content was determined according to method
described by price and Butlur (1977). Juice sample (0.06 gm) was
extracted with 3ml absolute methanol in a test tube, by constant
shaking for one minute, and then poured in to a filter paper. The tube
was quickly rinsed with an additional 3 ml of methanol and the
contents poured at once in to the filter paper. The filtrate was diluted
to 50 ml with distilled water, mixed with 3 ml 0.1M Fe Cl3 in 0.1 N
HCL for minutes, followed by the timed addition of 3 ml 0.008M
K3Fe (CN)6. The absorption was read after 10 minutes at 720nm on
spectrophotometer (corning, 259). In all cases, tannic acid was used as
a reference standard.
DF--- Dilute Factor
DF =
c x 56 x 100
60
29
3.2.9 Separan dose experiment:
Material:
Mixed juice.
Apparatus:
1.
Sedimentation Study Apparatus.
2.
Beakers (2000 ml).
3.
Cylinder (500 ml)
4.
Pipes.
5.
Distiller Water.
Reagent:
Separan.
Procedure:
Three samples of Separan weighing 1, 2, and 3 gram were taken
in different conical flasks (1000ml). Each flask was then filled with
distilled water to the 1000ml marks, and shacked to obtain even
solution. Samples of 1, 2, and 3 ml from the above were taken and
again diluted in 1000mls conical flasks to obtain Separan solution
with concentration of 1, 2 and 3ppm…etc (Fig. 2).
A sample of mixed juice was obtained from the factory before
addition of Separan, and heated to 90°C. The heated mixed juice was
divided into five Sedimentation Study Apparatus (1000ml size).
Separan either at 1, 2, 3, 4 and 5 ppm was added to each Cylinder, to
obtain a clarified juice. The parameters of clarified juice obtained
from each cylinder were the recorded as determined before, and
compared with parameter of the clarified juice in the factory.
30
Fig. (2): Sedimentation study apparatus in operation
31
3.3 Statistical analysis:
Data generated was subjected to analysis of variance using
randomized complete block design with five replications – Data
analyzed using MSTATC program, means were compared using
the Duncan's Multiple Ranges Test (DMRT), with a probability
(P≤0.05).
32
CHAPTER FOUR
RESULTS AND DICUSSIONS
4.1 Effect of milling on physicochemical properties of green and
burned cane:
Juice physicochemical parameters of both green and burned
cane are presented in Table (1) and Fig. (3).
Cane juice pol (sucrose), brix, reducing sugar (RS), purity and
pH of both green and burned cane were found to be similar and did
not differ significantly (P≤0.05). However there was a significant
(P≤0.05) difference between juice colour of burned (2600) and green
cane (53600) was observed.
Milling of green cane (53600) resulted in significant higher
colour reading than of burned cane (2600). This significant difference
in colour reading between burned and green cane could be due to
presence of chlorophyll.
The results obtained are in agreement with those obtained by
Steindl (2005) who stated that the amount and nature of colour
depends on the variety of sugarcane and also agree with those reported
by John (1988) who declared that chlorophyll is present in every green
plant.
It is noticeable that the reducing sugar level was found to be
higher in burned (1.10) cane than the green one (0.79). This could be
due to sucrose inversion in the presence of microbes in burned cane.
This matches with the findings of Joachim et al. (2000) who reported
33
Table (1): Effect of milling on physicochemical properties of green
and burned cane.
Treatment
Pol %
Brix%
Purity
Color/
Icumsa
R.S
pH
Green cane
18.15
(±1.27)
20.56
(±1.12)
88.28
(±4.70)
5360*
(±0.49)
0.79
(±0.52)
5.40
(±0.09)
Burned cane
18.14
(±0.94)
20.93
(±0.66)
86.67
(±1.88)
2600
(±0.32)
1.10
(±0.36)
5.40
(±0.20)
Values are means (±SD) of five replicates.
Means sharing star superscript are significantly different at (P≤0.05)
34
Green cane
Burned cane
Fig. (3): Sample of green and burned cane
35
That, when sucrose is inverted, as for example by means of an acid,
enzyme and micro organism. The molecule is broken up to give
glucose and fructose, i.e.
C12H22O11 + H2O
Sucrose
water
C6H12O6 + C6H12O6
glucose
fructose
Inverted sugars
4.2 Effect of processing on physicochemical parameters of burned
cane juice:
Physicochemical parameters of crushed, mixed and clarified
juice are presented in Table (2). The results obtained showed that pol,
brix and purity of crushed juice is higher than those of the clarified
and mixed juice.
The above quality parameters of both mixed and clarified juice
were comparable and not different significantly. The higher Brix
reading in the crushed juice (18.26) is due to the presence of high
amount and not easily tolerable colloidal matters as stated by Chen.
et al. (1993).
The results also showed that, the colour reading of both the
crushed (5569) and clarified juices (13009) were significantly
(P>0.05) higher compared to that of the mixed juice (3445). The high
colour value of the crushed juice could be due to the presence of
combinations of dyes in cane and ferric salts present in the crushed
juice as stated by Chen et al. (1993).
36
Table (2): Effect of processing on physicochemical parameters of burned cane juice.
Treatment
Pol %
Brix %
Purity
pH
A. Crushed juice
(untreated)
15.75*
(±1.82)
18.26*
(±1.85)
84.26
(±2.56)
5.42
(±0.81)
Color/
R.S
Turbidity
Icumsa
55.69*
1.04
14.00
(±0.81)
(±0.50)
(±1.04)
B. Mixed juice
(imbibitions water)
12.24
(±2.90)
12.86
(±1.27)
95.18*
(±3.55)
5.36
(±0.11)
3445*
(±0.83)
0.80
(±0.32)
12.09
(±0.75)
C. Clarified juice
(Saparan added)
12.99
(±1.87)
12.99
(±1.87)
94.96*
(±2.80)
6.80*
(±0.20)
13009*
(±0.76)
0.83
(±0.32)
9.47
(±0.73)
Value are means ( SD) of five replicates
Means values having different superscript. Star in columns differ significantly (P≤0.05)
Pol = Sucrose
RS = Reducing sugar
37
The very high colour reading of the clarified juice could be due
to the decomposition of its constituents by the action of added lime
(Kulk, 1998), iron salts present in the juice (Griffith, 1988), and or
subjection of both sugars and non sugars to heat, varying pH, iron
from equipments, added chemicals such as lime (Rein et al., 2007).
The application of heat or addition of chemicals (electrolytes)
during clarification process brings about flocculation or coagulation of
the colloidal matters and reduced clarified brix reading.
The results obtained in this study agree with the result obtained
by Perry’s (1988), who stated that cane juice has an acidic reaction at
pH 5.5.
According to Table (2) there is a significant difference (P<0.05)
between mixed (5.36) and clarified juices (6.80) regarding pH and
also there is a significant difference between crushed (5.42) and
clarified juice (6.80) in pH values. It is clear that, there is no
significant (P<0.05) difference of pH between crushed (5.42) and
mixed juice (5.63).
The change in pH from acidic in mixed juice to nearly neutral
in clarified juice could be due to the addition of lime. Spencer and
Meade (2001) described the purification in cane juice and stated that,
the lime added to neutralize the organic acids originally contained in
the juice.
4.3 Colouring substances in raw and processed materials:
The levels of polyphenols and tannin of different juice types are
presented in Table (3).
The percentage of polyphenol is significantly higher in green
cane (0.216) compared to that of burned cane (0.117). This is due to
38
Table (3): Colouring substances in the raw and processed materials.
Samples
Anti-nutrient
Polyphenols
Tannin
Green cane
0.216c
0.006d
Burned cane
0.117d
0.008d
Crushed juice
1.189a
0.005d
Mixed juice
0.094de
0.011d
Clarified juice
0.006f
0.008d
Syrup
0.037ef
0.008d
Final molasses
0.218c
2.146a
Overall mean
0.334
0.467
SE±
0.025
0.006
CV%
16.84
3.00
LSD
0.075
0.018
39
Juice colour which increased in green may be with trash and trash
tops. Reid and Lionnet (1989) stated that, the coloration in the juice
increased by 50 and 100% with trash and trash plus tops respect.
Regarding Tannin its percentage is higher in burned cane (0.008)
but not significantly compared to green cane.
The levels of polyphenols differ according to different types of
juice. The highest concentration of polyphenols was recorded in the
crushed juice (1.189), and the lowest level was found in clarified juice
(0.006), this colour increase may be due to equipment like juice pump.
Kul (1989) stated that the high level of polyphenols in crushed
juice is due to the presence of soluble iron salt (ferric) from
equipment.
The level of polyphenols in the final molasses (0.218) was
found to be significantly (P≤0.05) higher than that of clarified juice
(0.006), but at the same time is significantly lower than that of the
crushed juice (1.189).
Regarding tannin, the highest level was recorded in the final
molasses (2.146) flow by Syrup (0.468). The level of tannin in both
molasses and syrup is significantly higher than that in crushed (0.005),
mixed (0.011) and clarified juice (0.068). The level of tannin
recorded, in the three types of juices did not differ significantly. The
higher level of polyphenols and tannin in the syrup (0.468) and final
molasses (2.146) was expected, as the addition of separan to the
mixed juice enhances the formation of flogs containing tannins, which
eventually settle at the bottom of clarifier (John, 1988).
40
4.4 Effect of different doses of separan on juice quality parameter:
The effect of different doses of separan on juice quality is
presented in Table (4). The factory sample was taken as control
(3 ppm). As shown in Table (4) the concentration of pol decreases
with increase in separan concentration (ppm). Moreover all
parameters (except purity) were affected by separan concentration.
The highest pol (14.69) was obtained at 0.001 ppm dose of
separan. The highest brix reading (18.05) was recorded at the dose of
3 ppm (standard), which is significantly (P>0.05) higher than all other
samples. Different concentrations of separan showed no significant
effect on purity values.
The highest pH (7.60) was obtained at 0.006 ppm dose of
separan, but this not significantly different from other doses of
separan except the control sample, at which the pH value was 6.91.
The highest colour value (14692 ICUMSA) was obtained when
3 ppm of separan was applied and the lowest colour value (10894
ICUMSA) was obtained at 0.001 ppm of separan.
A technical report by Narspri (2006) stated that coluored nonsugars that are present in cane juice can be removed by various
chemical or physical processes. This may involve removal by
precipitating agents such as lime, phosphoric acid and separan that are
used in clarification.
The highest RS content (0.96) was obtained when 3 ppm of
separan (standard) was used. This level is significantly higher
than that obtained with the rest of separation concentrations. This
could be due to hydrolysis due to the higher temperature in heaters at
41
Table (4): Effect of different doses of separan (ppm) on juice quality parameters
Separan concentration (ppm)
Parameter 0.001
0.003
0.005
0.006
0.008
0.010
0.009
0.012
0.015
3*
Mean SE± CV% LSD
Pol
14.69a
13.58ab
13.53ab
13.55ab
13.50ab
12.47ab
13.12ab
13.07ab
10.18b
12.19ab 13.06
0.86
14.65 2.58
Purity
87.11a
86.17a
82.18a
83.81a
88.08a
85.57a
85.90a
87.43a
85.01a
84.87a
85.61
2.13
5.56
6.39
Turbidity
9.60a
8.53a
9.02a
8.47a
7.92ab
7.56ab
7.87ab
5.10b
4.96b
5.10b
7.358
0.11
3.29
0.33
pH
7.49a
7.43a
7.38a
7.60a
7.57a
7.32a
7.34a
7.29a
7.25a
6.91b
7.36
0.11
3.29
0.33
colour
10894b 12191ab
brix
14.69c
R.S
b
0.6
13068ab 13538ab 13417ab 13497ab 13120ab 13532ab 12570ab 14692a 13068 0.86
15.952bc 15.62bc
0.58
b
0.62
b
15.62bc
b
0.66
16.62abc 16.03abc 16.38abc 16.68abc 16.94ab
0.70
b
0.64
b
b
0.68
0.64
b
0.61
Values showing different superscript in a row are significantly different at (P≥0.05)
• Control sample (factory sample)
42
b
18.05a
0.96
a
14.69 2.58
8.48
1.86
16.36
0.62
0.66
0.051 16.90 0.15
the factory. This level is significantly higher than that of the vestige of
separation concentrations.
4.5 Effect of different doses of Saparan (ppm) on polyphenols and
tannins level:
The level of polyphenols and tannins of different doses of separan
(ppm) are presented in Table (5).
The level of polyphenols decreased as the concentration of
separan was increased. The highest level of polyphenols (0.009) is
recorded when 0.001 ppm separan is added, and when the concentration
of separan increased to 3 ppm (control), polyphenol significantly
(P>0.05) deceased to 0.006%. This is due to colour reaction between
sugars and various phenols, when concentrated mineral acids are present.
Joachim et al. (2000) Stated that the colorization of the clarified
juice is due to the combination of the sugar decomposition products,
such as furfural, and the condensation products from the phenol
derivatives. Tannin content was found to decrease with increase in
separan concentration.
The lowest tannin content (0.01) was found at separan
concentration of 0.010, 0.015 and 3 ppm.
Separan with 0.001, 0.003 and 0.005 ppm resulted in significant
(P>0.05) higher levels of tannins compared, with other separan levels.
The higher reading of tannin in the clarified juice is due to the
Reaction with iron salts. Therefore, the higher the concentration of
separan the lower tannin content. Colouring substances removal to a
great extent is dependent on proper addition of lime and separan. This
43
indicates that the higher the separan, concentration level the lower the
tannins levels in the juice. This in agreement with John (1988) who
stated that, tannin is normally removed by proper addition of separan to
the juice during clarification process.
44
Table (5): Effect of different doses of Separan (ppm) on polyphenols and
tannins level.
Separan
concentration
Anti-nutrient (%)
Polyphenols
Tannin
0.001
0.009a
0.08a
0.003
0.008ab
0.06b
0.005
0.007bc
0.06b
0.006
0.007bc
0.05bc
0.008
0.006cd
0.04c
0.009
0.005dc
0.02d
0.010
0.005de
0.01de
0.012
0.004ef
0.02de
0.015
0.033f
0.01c
3.000*
0.006cd
0.01c
Means
0.006
0.03
SE±
0.0002
0.01
CV%
9.39
30.18
LSD
0.0006
0.03
Means of similar letter(s) are significantly different
* Control sample
45
CHAPTER FIVE
CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusion:
Use of separan at very low concentration rations (0.015ppm)
resulted in a significantly better quality clarified juice as compared to the
standard or factory practice (3 ppm). This indicates the possibilities to
obtain high quality clarified juice with cheap less cost method.
4.2 Recommendation:
*
The results achieved encourage utilization of lower concentration
(0.015 ppm) of separan instead of standard practices applied (3
ppm) for production of clarified juice.
*
Utilization of (0.015) ppm for better sugar quality.
46
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