Journal of Food Processing and Preservation ISSN 1745-4549
EFFECT OF NANOCOMPOSITE PACKAGING CONTAINING AG
AND ZNO ON REDUCING PASTEURIZATION TEMPERATURE OF
ORANGE JUICE
jfpp_558
104..112
1,3
ARYOU EMAMIFAR , MAHDI KADIVAR2, MOHAMMAD SHAHEDI2 and SABIHE SOLIMANIAN-ZAD2
1
2
College of Agriculture, University of Kurdistan, Sanandaj 66177-15175, Iran
Department of Food Science and Technology, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran
3
Corresponding author.
TEL: 00988716620552;
FAX: 00988716620553;
EMAIL: [email protected]
Accepted for Publication February 26, 2011
doi:10.1111/j.1745-4549.2011.00558.x
ABSTRACT
Nanocomposite low-density polyethylene (LDPE) films containing Ag and ZnO
nanoparticles were prepared by melt mixing process through the twin-screw
extruder. Packages prepared from nanocomposite films were then filled with fresh
orange juice, pasteurized (at 55 and 65C for 16 s) and then stored at 4C. Microbial
stability, ascorbic acid (AA) content, browning index and color value of the juice
were evaluated after 7, 28, 56, 84 and 112 days of being stored. The two-way interaction between heat treatment and packaging type on the characteristics of the orange
juice was investigated. Consequently, application of LDPE nanocomposite packaging containing Ag markedly decreased the pasteurization temperature (65C) of
orange juice by 10C. Moreover, the reduced degradation of AA was observed in
orange juice, which was filled in nanocomposite packaging containing nano-ZnO.
PRACTICAL APPLICATIONS
Development of the novel technologies that offer reduced energy consumption and
increased quality of fruit juice are of the interest in the food industry. Compared
with pure packaging, antimicrobial nanocomposite packages containing Ag and
ZnO as an alternative nonthermal-processing technology can reduce the temperature of orange juice light pasteurization while produce juice with higher quality.
INTRODUCTION
Orange juice is the predominant juice manufactured by the
beverage-processing industry with a share of approximately
50% of the total fruit juice trade (Bull et al. 2004). Two type of
pasteurization are traditionally applied to citrus juices: full
pasteurization at 76–99C for a few seconds to 1 min and light
pasteurization at 66–75C for 1–16 s (Alwazeer et al. 2002).
Light pasteurization treatment is sufficient for inactive microorganisms and most enzymes provided that the product is
chemically, microbiologically and visually stable (Sadler et al.
1992). It is suggested that reduced heat may conserve energy
and time during heat processing (Shearer et al. 2002). Therefore, a great interest is increased in the development of novel
nonthermal technologies that offer the advantages of low
processing temperatures, low energy use, the retention of
nutrients and sensory attributes, while still inactivating
104
microorganisms to levels that do not pose a public health risk
(Smith et al. 2002). This has formed the basis of the successful
“hurdle technologies” that have fostered the development of
new routes to food preservation around the world. Proper use
of hurdles can appreciably lengthen shelf life of unpasteurized
juices without unduly affecting quality (Bates et al. 2001). In
accordance with this approach, rather than focusing solely on
an antimicrobial method, several sublethal treatments could
be used to achieve a safety level in the juice (Hodgins et al.
2002). However, sublethally injured cells are more susceptible
to antimicrobial components (Kalchayanand et al. 1994).
Nanotechnology as the new method in food packaging industry can potentially provide solutions to food packaging challenges, such as short shelf life (Joseph and Morrison 2006;
Chaudhry et al. 2008). Antimicrobials active packaging based
on metal nanocomposites, which are made by incorporating
some metal nanoparticles (NPs) such asAg,ZnO and CaO into
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.
A. EMAMIFAR ET AL.
the polymer films, are a new generation of nano food packaging (Chaudhry et al. 2008). The high performance in NPs is
due to high surface area/volume ratio,which is the main reason
for increasing antimicrobial activity of metal NPs (Damm
et al. 2006). NPs of Ag and ZnO are being used industrially for
several purposes (Gajjar et al. 2009). ZnO has been used in
many applications in daily life such as drug delivery, cosmetic
and filling in medical devices (Yan et al.2009),exhibited strong
antimicrobial activity on a broad spectrum of microorganisms
(Jones et al.2008).Moreover,it is currently listed as a generally
recognized as safe (GRAS) by the US Food and Drug Administration (Jin et al.2009).Silver has also long been known to have
antimicrobial inhibition (Lok et al. 2006). The antimicrobial
activity of these NPs may be related to several mechanisms
including, induction of oxidative stress because of the generation of reactive oxygen species (ROS), which may cause the
degradation of the membrane structure of cell (Sawai et al.
1998; Sawai 2003; Sawai and Yoshikawa 2004), the release of
ions from the surface of NPs that has been reported to lead bacterial death based on binding to cell membrane (Feng et al.
2000; Sondi and Salopek-Sondi 2004). However, the mechanism of toxicity is still only partially understood (Li et al.
2008). There are several methods to produce antimicrobial
polymer nanocomposites. Because of the thermal stability of
metal NPs, and the thermal processing method of producing
low-density polyethylene (LDPE) film as a contacting juice
layer in package, melt mixing is a good approach for this nanocomposite (Appendini and Hotchkiss 2002; Damm et al.2006;
Radheshkumar and Münstedt 2006). Recently, extensive
studies have been conducted to develop nonthermal processing techniques (pulsed electric field,high hydrostatic pressure,
ultraviolet [UV], ultrasonic) as replacements for thermal processing in order to keep the freshness of the juice along with
extending its shelf life (Tran and Farid 2004; Baxter et al. 2005;
Elez-Martínez et al.2006;Valero et al.2007).Although some of
these technologies are capable of decontaminating orange
juice, they are energy-intensive and require costly equipment;
hence, their yet relatively limited commercial applications
(Han 2007). Therefore, the main objectives of this research
were to evaluate the capabilities of ZnO andAg NP-filled LDPE
nanocomposite packaging as a new approach to reduction
light pasteurization temperature of orange juice.
MATERIALS AND METHODS
Preparation of Antimicrobial
Nanocomposite Films
Film grade LDPE resin pellets (LF0200, MFI 2 g/10 min,
density 0.92 g/mL, softening point 94C) and antimicrobial
agents including P105 powder (TiO2 95% + metal nanosilver
5% with particle diameters of about 10 nm) and ZnO NP
powder with an average particle diameter of about 70 nm (The
NANOPACKAGING ON PASTEURIZATION OF ORANGE JUCE
transmission electron microscopy [TEM] images can be found
in the previous paper [Emamifar et al. 2011]) were obtained
from Pars Nanonasb (Tehran, Iran). Film grade LDPE resin
pellets (0.9 kg) were directly mixed with each of the antimicrobial agents (P105 and nano-ZnO particles; 0.1 kg) separately
and the mixture was fed into a twin-screw extruder machine
(Cincinnati Milacron, Batavia, OH, USA) with a screw diameter of 55 mm and a screw length/diameter ratio of 30 mm to
be cut into masterbatch nano-granules. The mass fraction of
the filler for each antimicrobial agent was 10%. The heating
profile was set to six heating zones of the twin-screw extruder
including 160, 160, 175, 150, 150 and 140C. Proper amounts of
masterbatch resins were then added to pure LDPE resin pellets
into a single-screw blowing machine with a screw diameter of
45 mm and a length/diameter ratio of 28 mm (Venus Plastic
Machinery, Minsyong Township, Taiwan) to fabricate the final
nanocomposite film (50-mm thick) with the desired nanomaterial concentrations (0.25 and 1% for nano-ZnO and 1.5 and
5% for P105). The temperature profile for the single extruder
was maintained at 190C in the two barrel zones.Film thickness
was measured using a micrometer (Mitutoyo, Kawasaki,
Japan) and reported as the average of five readings taken at five
different points on the film sample.
TEM Analysis
Dispersion quality of nanomaterials into the polymer matrix
film was monitored using the transmission electron microscope (PHILIPS CM 200 kV, Eindhoven, the Netherlands).
Preparation and Processing of Orange Juice
To prepare natural orange juice, 30 kg of oranges (Citrus sinensis cv. Khaf) were purchased from the local market in
Isfahan, Iran. They were juiced using a semi-industrial juice
extractor (M2000A-1, CMEC Food Machinery, Suzhou,
China) equipped with a central fruit-halving knife and a pair
of holding cups, 90 mm in diameter, thoroughly washed with
detergent and hot water. The juice, with an efficiency of
25.8%, was passed through a 1-mm mesh filter and was
immediately transferred into a sterile glass container under
sanitized conditions. Packages were prepared by a hand heat
sealer using antimicrobial nanocomposite and pure LDPE
films 15 ¥ 10 cm in size, similar to Doypack packaging commonly used for packaging fruit juice. The packages were
immediately wrapped in aluminum foil and sanitized at 95C
for 2 min. After cooling and under a sterile laboratory hood,
175 mL of fresh orange juice was poured into each package
and sealed by the heat sealer. Thermal pasteurization of the
samples were performed using steam tunnel, with direct
injection of steam on the packages, at two regimens of pasteurization, 65 and 55C for 16 s, followed by rapid cooling in
an ice water bath to 4C.
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.
105
NANOPACKAGING ON PASTEURIZATION OF ORANGE JUCE
A. EMAMIFAR ET AL.
Storage
Browning Index Measurement
After thermal processing, packages containing orange juice
were stored in dark and cool conditions (4C). The samples
were analyzed for microbiological and physicochemical characteristics immediately after packaging and after 7, 28, 56, 84
and 112 days of storage.
To determine the browning index of the samples, 10 mL of
the sample orange juice was centrifuged (10 min, 7800 ¥ g at
4C) and 5 mL of ethyl alcohol (95%) was added to 5 mL of the
juice supernatant followed by centrifuging the mixture again
under the same conditions. The absorbance of the supernatant was read at 420 nm using a spectrophotometer (2100UV, Unico, Dayton, NJ) according to the method described by
Meydav et al. (1977).
Microbiological Evaluations
Decimal dilutions were prepared from orange juice samples
with sterile peptone water (0.1%). Volumes of dilution
samples (0.1 mL) were then used. Total aerobic plate counts
were enumerated using the pour plate method on the plate
count agar (Scharlau Chemie, S.A., Barcelona, Spain). Incubation was performed at 30C for 3 days. Total yeast and molds
were enumerated using the surface plate method on the potato
dextrose agar (Scharlau Chemie) +10% tartaric acid. Incubation for total yeast and mold counts was performed at 25C for 5
days. Each test was performed in duplicate and results were
expressed as colony-forming units per milliliter (cfu/mL).
Ascorbic Acid Degradation
Most chemical analyses are based on the fact that ascorbic
acid is easily oxidized. The most common method relies on
the reduction of 2, 6 dichlorophenolindophenol reagent.
Ascorbic acid degradation was determined using the titrimetric method (AOAC 2002a, 967.21).
Metal Ions Releasing Measurement
Silver and zinc ions releasing into the orange juice were determined using standard methods (AOAC 2002b,974.27) slightly
modified by Bings et al. (2006) using a graphic furnace atomic
absorption spectrometer (AA800, Perkin-Elmer, Shelton, CT,
USA) operated at 328.1 and 213.9 nm wavelengths.
Statistical Analysis
Analyses of variance of data was carried out using SAS statistical software release 6.12 (SAS Institute, Cray, NC, USA). Factorial experiments including packaging type (five levels),
pasteurization temperature (two levels) and storage duration
(six levels), were done, in duplicate, based on completely randomized designs. Significant differences among data were
represented as P < 0.05.
RESULTS AND DISCUSSION
TEM
Color Measurement
Color was measured using a digital imaging method that used
a combination of a digital camera (Panasonic, Osaka, Japan),
a computer and a graphics software. A petri dish containing
25 mL of orange juice was placed into the lighting system that
consisted of two CIE source D65 lamps 45.0 cm long,
mounted on the two sides of a frame installed on either side of
the Petri dish, 30.5 cm above and at an angle of 45° to the
orange juice sample plane. Images of the bottom surface of
the orange juice were taken and saved using the digital camera
that was placed 30.5 cm above the sample with its lens facing
downwards toward the orange juice. The color was analyzed
using the Photoshop software. By turning on the grid feature
in Photoshop, a grid was superimposed on the sample. As the
computer pointer was placed at a grid point along the x or y
axis, L, a and b-values corresponding to the pixels of that grid
point were obtained from the Info Palette. The total color difference (DE = [(DL)2 + (Da)2 + (Db)2)]1/2) was determined in
duplicate using CIE L, a, and b-values (Yam and Papadakis
2004).
106
The TEM image of nanocomposite indicated that the NPs
were well dispersed in the polymer matrix. As the nano-ZnO
content increased to 1%, the quantity of the agglomerates
increased. Full details can be found in the previous paper
(Emamifar et al. 2010).
Microbial Analysis
Mean initial microbial population immediately after
packaging and before pasteurization was determined to
be 4.93 log cfu/mL for fungi (yeast and molds) and
4.83 log cfu/mL for total aerobic bacteria in orange juice.
However, the final microbial population immediately after
heating at 55C reduced to 2.55 log cfu/mL for fungi (yeast and
molds) and 2.12 log cfu/mL for total aerobic bacteria, and at
65C reduced to 1.73 log cfu/mL and 1.31 log cfu/mL respectively in all the orange juice test packages. In these evaluations,
the treatment of pure LDPE packaging and pasteurization
temperature (65C) was supposed as a control (0.0) as compare
with other treatments. Significant differences (P < 0.05)
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.
A. EMAMIFAR ET AL.
NANOPACKAGING ON PASTEURIZATION OF ORANGE JUCE
5
log cfu/ml
a
a
4
b
3
c
d
g
2
h
d
e
f
1
0
FIG. 1. EVALUATION OF THE TWO-WAY
INTERACTION EFFECTS BETWEEN PACKAGING
TYPE AND PASTEURIZATION TEMPERATURE ON
FUNGI POPULATION OF ORANGE JUICE
LDPE, low-density polyethylene.
Pure LDPE
LDPE+1.5%
P105
LDPE+5%
P105
LDPE+0.25%
NanoZnO
LDPE+1%
NanoZnO
0.0
-0.6
-0.9
-0.4
0.0
65C
1.7
0.1
-0.6
0.8
1.6
55C
packaging type
among the interaction effects data of packaging type and pasteurization temperature on microbial populations in orange
juice were observed. Figures 1 and 2 indicate that in all antimicrobial packages containing 1% nano-ZnO except LDPE, the
pasteurization caused a significant decrease in fungi and total
bacteria populations compared with packages made from
pure LDPE. By increasing nano-ZnO concentration to 1%, the
antimicrobial activity of the film decreased. The reduced antimicrobial activity of ZnO powder might be related to the
increasing particle size, which might decrease the generation
of H2O2 from the surface of ZnO powder (Yamamoto 2001).
When the temperature treatment decreased from 65 to 55C,
cell viability in LDPE pure packages increased to about to
1.2 log cfu/mL and 1.7 log cfu/mL,for total bacteria and fungi
population respectively, as compared with control (65C).
According to Fig. 1, incorporation of 5% P105 in LDPE
reduced the population of fungi in orange juice by -0.6 log
cfu/mL at 55C. However, the films that contain nano-ZnO did
not show this kind of effect. Moreover, application of nanocomposite packaging containing 1.5 % P105-assisted thermal
processing at 55C resulted in fungi population reduction of
0.1 log cfu/mL, which is approximately in the range of control
(0.0).Therefore,it is possible to reduce the pasteurization temperature for fungi to up to 10C. However, the same treated was
shown when total bacterial counts was determined. Combina-
tion of 5% P105 and reduced temperature (55C) exhibited a
pronounced effect on the destruction of bacteria in orange
juice (Fig. 2).Sawai andYoshikawa (2004) have concluded that
ZnO, CaO and MgO powders have satisfactory antimicrobial
effects against a broad spectrum of microorganisms, but that
ZnO has a poor antimicrobial effect on Saccharomyces cerevisiae and other yeasts and molds compared with bacteria.Based
on our results (Figs. 1 and 2),the antimicrobial effect of Ag NPs
is much higher than that of ZnO NPs. However, it seems that
LDPE + 5% P105 has a significantly (P < 0.05) higher antimicrobial activity compared with other nanocomposites for
orange juice at 4C.
NPs of silver can damage cell membranes of microorganisms, by the formation of “pits” on their surfaces. Moreover,
NPs of silver may penetrate into the cell and cause DNA
damage (Sondi and Salopek-Sondi 2004; Morones et al.2005).
Silver ions, which may be released from the surface of these
NPs, can interact with thiol groups in protein, which induce
the inactivation of the bacteria and cause DNA molecules to
become condensed and lose their replication abilities (Feng
et al. 2000). Kim et al. (2007) indicated that the antimicrobial
mechanism of Ag NPs is related to the formation of free radicals, based on electron spin resonance measurements and subsequent free radical-induced membrane damage. TiO2 is
widely used as a photocatalyst because it is relatively highly
4
log cfu/ml
a
a
3
2
b
c
d
d
e
f
g
h
1
0
FIG. 2. EVALUATION OF THE TWO-WAY
INTERACTION EFFECTS BETWEEN PACKAGING
TYPE AND PASTEURIZATION TEMPERATURE ON
TOTAL BACTERIAL COUNTS POPULATION OF
ORANGE JUICE
LDPE, low-density polyethylene.
Pure LDPE
LDPE+1.5%
P105
0.0
1.2
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.
LDPE+5% P105
LDPE+0.25%
NanoZnO
LDPE+1%
NanoZnO
-0.5
-1.0
-0.5
0.0
0.4
-0.2
0.3
1.1
65C
55C
Packaging type
107
NANOPACKAGING ON PASTEURIZATION OF ORANGE JUCE
A. EMAMIFAR ET AL.
efficient, cheap, nontoxic, chemically and biologically inert,
and photo stable (Ubonchonlakat et al. 2008). The antibacterial activity of TiO2 is related to ROS production, especially
hydroxyl free radicals and peroxide formed under UV-A irradiation via oxidative and reductive pathways respectively (Li
et al. 2008). Despite the positive attributes of TiO2, there are a
few drawbacks associated with its use. It has a high bandgap
(e.g., >3.2 eV) and it is excited only by UV light (l < 388 nm)
to inject electrons into the conduction band and to leave holes
into the valence band. In addition, the high rate of electronhole recombination on TiO2 particles results in a low efficiency
of photocatalysis (Sobana et al. 2006). Many studies have been
devoted to the improvement of photoactivity of TiO2 by
depositing noble metals (Xin et al. 2005). Silver has attracted
the interests of several researchers because of its novel effects
on the improvement of photoactivity of semiconductor photocatalysis and its effects on antibacterial activity (Sobana et al.
2006). Ag species simultaneously doped and deposited on the
surface layer of TiO2 can effectively capture the photoinduced
electrons and holes, inhibit recombination of photoinduced
electrons and holes, lead to photogenerated charge carrier
concentration rising and photoinduced electrons can quickly
transport to the oxygen adsorbed on the surface of TiO2 (Xin
et al.2005).However,Ag/TiO2 shows great promise as a photocatalytic material because of its photoreactivity and visible
light response (Li et al. 2008) and are found to be significantly
more photocatalytically and antimicrobially active than a
titania coating (Kumar and Raza 2009). Zhang and Chen
(2009) showed that by doping TiO2 with metallic form of
nanosilver, the bactericidal activity increased because of its
unique structural feature of nanosilver dispersed on the TiO2
surface and indicated that TiO2 serve as a solid antiaggregation
support to maintain the dispersion of nanosilver, which could
also contribute to the antibacterial performance. Kubacka
et al. (2009) described that nanocomposites ethylene-vinyl
alcohol copolymer (EVOH) containing mixed Ag-TiO2 have a
good antimicrobial activity against fungi and bacteria through
a plasmonic effect. The interaction not only optimizes the
UV/visible photon handling (excitation/de-excitation) by the
films but also makes the whole surface of the nanomaterial biocidal and eliminates the necessity of contact between the
primary biocidal inorganic agent and the microorganisms.
Fernández et al. (2009) reported that absorbent pads containing nanosilver are a common component in packaging to persevere poultry meat up to consumption and they can reduce a
log reduction up to 40% of aerobic mesophilic bacteria.
Antimicrobial effects of ZnO NPs may be attributed to
several mechanisms: (1) induction of oxidative stress because
of generation ROS, especially H2O2 interior or out of cell,
which lead to interaction with proteins, DNA, lipids and death
(Sawai et al. 1998; Sawai 2003; Sawai and Yoshikawa 2004;
Adams et al. 2006); (2) membrane disorganization because of
accumulation of ZnO NPs in the bacterial membrane and also
108
cellular internalization of them (Brayner et al. 2006); and (3)
releasing Zn ions that may be responsible for antimicrobial
activity by binding to the membrane of microorganisms
(Gajjar et al. 2009). However, the toxicity of ZnO NPs is not
directly related to enter them into the cell, but the intimate
contact these particles to the cell cause changes in microenvironment in the vicinity of organism–particle contact area and
either increases solubilization of metal or generated ROS that
may damage cell membrane (Heinlaan et al. 2008). Moreover,
the toxicity of ZnO NPs is not only affected by the light via the
production of ROS, but also may happen at dark conditions,
although its mechanism is still not defined (Adams et al.2006).
Jin et al. (2009) studied several approach (powder, film, polyvinylpyrrolidone capped and coating) for application of
nano-ZnO into food systems, and concluded that nano-ZnO
possess antimicrobial activity against L.monocytogenes and
S.enteritidis in liquid egg white and culture media.
Ascorbic Acid and Browning Index
Ascorbic acid is usually degraded by oxidative processes,which
are stimulated in the presence of light, oxygen, heat, peroxides
and enzymes (Plaza et al. 2006). The quantities of AA and
browning index in the fresh orange juice immediately after
packaging was measured at 86 mg/100g, and 0.15. AA destruction beyond pasteurization treatment in whole orange concentrate is known to be affected significantly by storage time
and temperature (Falade et al.2004).Bull et al.(2004) describe
that the browning index of the orange juice increases after
thermal treatments (65C, 1 min). However, Leizerson and
Shimoni (2005) reported that increased values of browning
index by up to 0.367 is still invisible. Increasing temperature
has a major effect on the increased rate of browning reaction in
fruit juice (Koca et al. 2003). Based on Figs. 3 and 4, ascorbic
acid loss and brown pigments development in LDPE + 5%
P105 were significantly higher than other packages while the
rates of these changes were reduced by decreasing nanosilver
concentration in LDPE + 1.5% P105. This indicates that ROS,
which might be responsible for antimicrobial activity may also
increase ascorbic acid losses (Choe et al. 2005). Moreover, it
can be obseved that application of the antimicrobial nanocomposite pacakaging at 55C not only reduced browning
index (-7.5% in LDPE + 0.25% nano-ZnO), but also
improved AA retention (e.g., 13.4% more in compared with
control), indicating the pronounced hurdle effects of NPs and
mild heat to improve the quality attributes of orange juice.
Color
Orange juice color is mainly due to the presence of carotenoid
pigments and is influenced by product ripening, processing
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.
NANOPACKAGING ON PASTEURIZATION OF ORANGE JUCE
Ascorbic Acid (mg /100g)
A. EMAMIFAR ET AL.
42
a
a
b
c
d
39
f
36
g
e
g
h
33
30
Pure LDPE
LDPE+1.5%
P105
LDPE+5%
P105
LDPE+0.25%
NanoZnO
LDPE+1%
NanoZnO
0.0%
-0.3%
-2.0%
1.1%
-4.4%
11.0%
12.9%
9.9%
13.4%
6.7%
FIG. 3. EVALUATION OF THE TWO-WAY
INTERACTION EFFECTS BETWEEN PACKAGING
TYPE AND PASTEURIZATION TEMPERATURE ON
RETENTION OF ASCORBIC ACID IN ORANGE
JUICE
LDPE, low-density polyethylene.
65C
55C
Packaging type
Browning Index (OD)
treatments, storage conditions and browning reactions
(Cortés et al. 2008). As shown in Fig. 5, orange juice were
packed in LDPE + 0.25% nano-ZnO presented the lowest
total color differences at both 55 and 65C. Moreover, the
changes in total color differences of orange juice for all the test
packages at 55C were significantly less than 65C. These
changes correlated well with the reduction of ascorbic acid
and production of brown pigments during storage (Figs. 3
and 4). Bleaching effect in orange juice might be due to the
oxidative degradation of carotenoids (Haugaard et al. 2002);
thus, the free radicals in antimicrobial orange juice packaging
might be responsible for the change in DE.
Metal Ions Releasing Measurement
The quantities of silver and zinc ions in the orange juice after
112 days of storage are shown in Table 1. The quantity of silver
ions migrating into the orange juice after 112 days was less than
its allowable concentration (10 ppm).It has been reported that
silver ions at as low concentrations as 10-9 mole/L have an anti-
0.36
a
0.34
b
c
0.32
c
d
d
e
e
f
g
0.3
0.28
0.26
Pure LDPE
FIG. 4. EVALUATION OF THE TWO-WAY
INTERACTION EFFECTS BETWEEN PACKAGING
TYPE AND PASTEURIZATION TEMPERATURE ON
BROWNING INDEX OF ORANGE JUICE
LDPE, low-density polyethylene.
LDPE+1.5%
P105
LDPE+5%
P105
LDPE+0.25%
NanoZnO
LDPE+1%
NanoZnO
0.0%
-0.9%
2.4%
-3.6%
6.7%
-3.9%
-6.4%
-2.3%
-7.5%
0.8%
65C
55C
Packaging type
200
160
120
E
a
c
b
d
h
e
f
i
g
j
80
40
0
FIG. 5. EVALUATION OF THE TWO-WAY
INTERACTION EFFECTS BETWEEN PACKAGING
TYPE AND PASTEURIZATION TEMPERATURE ON
TOTAL COLOR DIFFERENCE (DE) OF ORANGE
JUICE
LDPE, low-density polyethylene.
Pure LDPE
LDPE+1.5%
P105
LDPE+5%
P105
LDPE+0.25%
NanoZnO
LDPE+1%
NanoZnO
0.0%
-1.1%
8.0%
-5.7%
20.8%
65C
-26.7%
-30.3%
-19.0%
-32.3%
-4.3%
55C
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.
Packaging type
109
NANOPACKAGING ON PASTEURIZATION OF ORANGE JUCE
A. EMAMIFAR ET AL.
TABLE 1. THE QUANTITY OF AG AND ZN IONS (MEAN⫾SD) RELEASED FROM NANOCOMPOSITE LDPE FILMS CONTAINING AG AND ZNO
NANOPARTICLES IN ORANGE JUICE DURING STORAGE
Concentration
ions (mg/L)
Storage
time (days)
Silver
28
56
84
112
28
56
84
112
Zinc
Film type
LDPE + 1.5% P105
LDPE + 5% P105
LDPE + 0.25% nano-ZnO
LDPE + 1% nano-ZnO
ND
ND
ND
ND
–
–
–
–
0.1 ⫾ 0.003
0.11 ⫾ 0.005
0.13 ⫾ 0.005
0.15 ⫾ 0.002
–
–
–
–
–
–
–
–
0.16 ⫾ 0.007
0.26 ⫾ 0.006
0.48 ⫾ 0.002
0.68 ⫾ 0.002
–
–
–
–
0.11 ⫾ 0.003
0.13 ⫾ 0.004
0.30 ⫾ 0.005
0.54 ⫾ 0.005
LDPE, low-density polyethylene; ND, not detected.
microbial effect in water (Damm et al. 2006). Moreover, the
quantity of zinc ions indicated a higher rate of Zn migration
than that of silver but as zinc is proved to be a GRAS compound
for food applications, its low concentration is in the acceptable
range for food consumers (Jin et al. 2009).
CONCLUSIONS
This study showed that application of LDPE nanocomposite
packaging materials containing Ag and ZnO NPs is a new
approach for preserving and extending the shelf life of light
pasteurized orange juice at 4C. The quality of the packaging
film including good dispersion of nanomaterials in the
polymer matrix and being free from agglomeration was
shown to be very effective on the antimicrobial effects of these
packaging materials. However, there was a statistically significant two-way interaction (P < 0.05) between heat treatment
and packaging type on the microbiological and physicochemical characteristics of the packed orange juice. Application of LDPE + 5% P105 packages in combination with both
heat treatments (55 and 65C) showed significantly (P < 0.05)
more antimicrobial performance than others. It was also
noticeable that the most retention of AA and microbial reduction in orange juice was achieved by using the LDPE + 1.5%
P105 packages at 55C as compared with control sample
(LDPE pure and 65C). Moreover, the antimicrobial activity of
nanosilver against fungi (yeast and molds) compared with
ZnO NPs, at the same concentration, was more pronounced.
ACKNOWLEDGMENTS
We gratefully acknowledge financial support from Isfahan
University of Technology.
REFERENCES
ADAMS, L.K., LYON, D.Y. and ALVAREZ, P.J.J. 2006.
Comparative eco-toxicity of nanoscale TiO2, SiO2, and ZnO
water suspensions. Water Res. 40, 3527–3532.
110
ALWAZEER, D., CACHON, R. and DAVIS, C. 2002. Behavior of
Lactobacillus plantarum and Saccharomyces cerevisiae in fresh
and thermally processed orange juice. J. Food Prot. 65,
1586–1589.
Association of Official Analytical Chemists (AOAC) 2002a.
Vitamin C (ascorbic acid) in vitamin preparations and juices: 2,
6 dichloroindophenol titrimetric method final action. Official
Methods of Analysis of AOAC International, W. Horwitz (Ed),
(17th ed). Association of Official Analytical Chemists,
Gaithersburg, MD, Official Method 967.21.
Association of Official Analytical Chemists (AOAC) 2002b.
Cadmium, chromium, copper, iron, lead, magnesium,
manganese, silver, and zinc in water. Official Methods of Analysis
of AOAC International, W. Horwitz (Ed), (17th ed). Association
of Official Analytical Chemists, Gaithersburg, MD, Official
Method 974.27.
APPENDINI, P. and HOTCHKISS, J.H. 2002. Review of
antimicrobial food packaging. Innov. Food Sci. Emerg. Technol.
3, 113–126.
BATES, R.P., MORRIS, J.R. and CRANDALL, P.G. 2001. Principles
and Practices of Small- and Medium-Scale Fruit Juice Processing,
pp. 63–95, FAO, Rome, Italy.
BAXTER, I.A., EASTON, K., SCHNEEBELI, K. and WHITFIELD,
F.B. 2005. High pressure processing of Australian navel orange
juices: Sensory analysis and volatile flavor profiling. Innov.
Food Sci. Emerg. Technol. 6, 372–387.
BINGS, N.H., BOGAERTS, A. and BROEKAERT, J.A.C. 2006.
Atomic spectroscopy. Anal. Chem. 78, 3917–3945.
BRAYNER, R., FERRARI-LLIOU, R., BRIVOIS, N., DJEDIAT, S.,
BENEDETTI, M.F. and FIÉVET, F. 2006. Toxicological
impact studies based on Escherichia coli bacteria in
ultrafine ZnO nanoparticles colloidal medium. Nano Lett. 6,
866–870.
BULL, M.K., ZERDIN, K., HOWE, E., GOICOECHEA, D.,
PARAMANANDHAN, P., STOCKMAN, R., SELLAHEWA, J.,
SZABADO, E.A., JOHNSON, R.L. and STEWART, C.M. 2004.
The effect of high pressure processing on the microbial,
physical and chemical properties of Valencia and Navel orange
juice. Innov. Food Sci. Emerg. Technol. 5, 135–149.
CHAUDHRY, Q., SCOTTE, M., BLACKBURN, J., ROSS, B.,
BOXALL, A. and CASTLE, L. 2008. Applications and
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.
A. EMAMIFAR ET AL.
implications of nanotechnologies for the food sector. Food
Addit. Contam. 25, 241–258.
CHOE, E., HUANG, R. and MIN, D.B. 2005. Chemical reactions
and stability of riboflavin in foods. J. Food Sci. 70, 28–36.
CORTÉS, C., ESTEVE, M.J. and FRÍGOLA, A. 2008. Color of
orange juice treated by high intensity pulsed electric fields
during refrigerated storage and comparison with pasteurized
juice. Food Control 19, 151–158.
DAMM, C., NEUMANN, M. and MÜNSTEDT, H. 2006.
Properties of nanosilver coatings on polymethyl methacrylate.
Soft Mater. 3, 71–88.
ELEZ-MARTÍNEZ, P., SOLIVA-FORTUNY, R.C. and
MARTÍN-BELLOSO, O. 2006. Comparative study on shelf life
of orange juice processed by high intensity pulsed electric fields
or heat treatment. Eur. Food. Res. Technol. 222, 321–329.
EMAMIFAR, A., KADIVAR, M., SHAHEDI, M. and
SOLAIMANIANZAD, S. 2010. Evaluation of nanocomposite
packaging containing Ag and ZnO on the shelf life of
fresh orange juice. Innov. Food Sci. Emerg. Technol. 11,
742–748.
EMAMIFAR, A., KADIVAR, M., SHAHEDI, M. and
SOLAIMANIANZAD, S. 2011. Effect of nanocomposite
packaging containing Ag and ZnO on inactivation of
Lactobacillus plantarum in orange juice. Food Control 22,
408–413.
FALADE, K.O., BABALOLA, S.O., AKINYEMI, S.O.S. and
OGUNLADE, A.A. 2004. Degradation of quality attributes of
sweetened Julie and Ogbomoso mango juices during storage.
Eur. Food. Res. Technol. 218, 456–459.
FENG, Q.L., WU, J., CHEN, G.Q., CUI, F.Z., KIM, T.N. and KIM,
J.O. 2000. A mechanistic study of the antibacterial effect of
silver ions on Escherichia coli and Staphylococcus aureus. J.
Biomed. Mater. Res. 52, 662–668.
FERNÁNDEZ, A., SORIANO, E., LÓPEZ-CARBALLO, G.,
PICOUET, P., LLORET, E., GAVARA, R. and
HERNÁNDEZ-MUÑOZ, P. 2009. Preservation of aseptic
conditions in absorbent pads by using silver nanotechnology.
Food Res. Int. 42, 1105–1112.
GAJJAR, P., PETTEE, B., BRITT, D.W., HUANG, W., JOHNSON,
W. and ANDERSON, A.J. 2009. Antimicrobial activities of
commercial nanoparticles against an environmental soil
microbe, Pseudomonas putida KT2440. J. Biol. Eng. 3,
1183–1189.
HAN, J.H. 2007. Packaging for nonthermally processed foods. In
Packaging for Nonthermal Processing of Food, (J.H. Han, ed.) pp.
213–225, Wiley–Blackwell, Ames, IA.
HAUGAARD, V.K., WEBER, C.J., DANIELSEN, B. and
BERTELSEN, G. 2002. Quality changes in orange juice packed
in materials based on polylactate. Eur. Food Res. Technol. 214,
423–428.
HEINLAAN, M., IVASK, A., BLINOVA, I. and DUBOURGUIER,
H.C. 2008. Toxicity of nanosized and bulk ZnO, CuO and
TiO2 to bacteria Vibrio fischeri and crustaceans Daphnia
magna and Thamnocephalus platyurus. Chemosphere 71,
1308–1316.
NANOPACKAGING ON PASTEURIZATION OF ORANGE JUCE
HODGINS, A.M., MITTAL, G.S. and GRIFFITHS, M.W. 2002.
Pasteurization of fresh orange juice using low energy pulsed
electric field. J. Food Sci. 67, 2294–2299.
JIN, T., SUN, D., SU, J.Y., ZHANG, H. and SUE, H.J. 2009.
Antimicrobial efficacy of zinc oxide quantum dots against
Listeria monocytogenes, Salmonella enteritidis, and Escherichia
coli O157:H7. J. Food Sci. 74, 46–52.
JONES, N., RAY, B., RANJJIT, K.T. and MANNA, A.C. 2008.
Antibacterial activity of ZnO nanoparticle suspensions on a
broad spectrum of microorganisms. FEMS Microbiol. Lett.
279, 71–76.
JOSEPH, T. and MORRISON, M. 2006. Nanotechnology in
agriculture and food. A Nanoforum report, 15PP.
http://www.nanoforum.org (accessed April 13, 2006).
KALCHAYANAND, N., SIKES, A., DUNNE, C.P. and RAY, B.
1994. Hydrostatic pressure and electroporation have increased
bactericidal efficiency in combination with bacteriocins. Appl.
Environ. Microbiol. 60, 4174–4177.
KIM, J.S., KUK, E., YU, K., KIM, J.H., PARK, S.J., LEE, S.J. et al.
2007. Antimicrobial effects of silver nanoparticles. Nanomed.
Nanotechnol. Biol. Med. 3, 95–101.
KOCA, N., BURDURLU, H.S. and KARADENIZ, F. 2003. Kinetics
of nonenzymatic browning reaction in citrus juice concentrates
during storage. Turk. J. Agric. Forest. 27, 353–360.
KUBACKA, A., CERRADA, M.L., SERRANO, C.,
FERNÁNDEZ-GARCÍA, M., FERRE, M. and
FERNÁNDEZ-GARCÍA, M. 2009. Plasmonic
nanoparticle/polymer nanocomposites with enhanced
photocatalytic antimicrobial properties. J. Phys. Chem. 113,
9182–9190.
KUMAR, R.V. and RAZA, G. 2009. Photocatalytic disinfection of
water with Ag- TiO2 nanocrystalline composite. Ionics 15,
579–587.
LEIZERSON, S. and SHIMONI, E. 2005. Stability and sensory
shelf life of orange juice pasteurized by continuous ohmic
heating. J. Agric. Food Chem. 53, 4012–4018.
LI, Q., MAHENDRA, S., LYOUN, D.Y., BRUNET, L., LIGA, M.V.
and LI, D. 2008. Antimicrobial nanomaterials for water
disinfection and microbial control: Potential applications and
implications. Water Res. 42, 4591–4602.
LOK, C.N., HO, C.M., CHEN, R., HE, Q.Y., YU, W.Y., SUN, H.,
TAM, P.K., CHIU, J.F. and CHE, C.M. 2006. Proteomic analysis
of the mode of antibacterial action of silver nanoparticles. J.
Proteome Res. 5, 916–924.
MEYDAV, S., SAGUY, I. and KOPELMAN, I.J. 1977. Browning
determination in citrus products. J. Agric. Food Chem. 25,
602–604.
MORONES, J.R.E., ELECHIGUERRA, J.L., CAMACHO, A.,
HOLT, K., KOURI, J.B., RAMÍREZ, J.T. and YACAMAN, M.J.
2005. The bactericidal effect of silver nanoparticles.
Nanotechnology 16, 2346–2353.
PLAZA, L., SÁNCHEZ-MORENO, C., DE ANCOS, B.,
MARTÍN-BELLOSO, O. and CANO, M.P. 2006. Effect of
refrigerated storage on vitamin C and antioxidant activity of
orange juice processed by high-pressure or pulsed electric fields
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.
111
NANOPACKAGING ON PASTEURIZATION OF ORANGE JUCE
A. EMAMIFAR ET AL.
with regard to low pasteurization. Eur. Food Res. Technol. 223,
487–493.
RADHESHKUMAR, C. and MÜNSTEDT, H. 2006.
Antimicrobial polymers from polypropylene/silver
composites-Ag+ release measured by anode stripping
voltammetry. React. Funct. Polym. 66, 780–788.
SADLER, G.D., PARISH, M.E. and WICKER, L. 1992. Microbial,
enzymatic, and chemical challenges during storage of fresh and
processed orange juice. J. Food Sci. 57, 1187–1192.
SAWAI, J. 2003. Quantitative evaluation of antibacterial activities
of metallic oxide powders (ZnO, MgO and CaO) by
conductimetric assay. J. Microbiol. Methods 54, 177–182.
SAWAI, J., SHOJI, S., IGARASHI, H., HASHIMATO, A.,
KOKUGAN, T. and SHIMIZU, M. 1998. Hydrogen peroxide as
an antibacterial factor in zinc oxide powder slurry. J. Ferment.
Bioeng. 86, 521–522.
SAWAI, J. and YOSHIKAWA, T. 2004. Quantitative evaluation of
antifungal activity of metallic oxide powders (MgO, CaO and
ZnO) by an indirect conductimetric assay. J. Appl. Microbiol.
96, 803–809.
SHEARER, A.E.H., MAZZOTTA, A.S., CHUYATE, R. and
GOMBAS, D.E. 2002. Heat resistance of juice spoilage
microorganisms. J. Food Prot. 65, 1271–1275.
SMITH, K., MITTALL, G.S. and GRIFFIITHS, M.W. 2002.
Skim milk pasteurization by pulsed electrical field and
antimicrobials. J. Food Sci. 67, 2304–2308.
SOBANA, N., MURUGANADHAM, M. and SWAMINATHAN,
M. 2006. Nano-Ag particles doped TiO2 for efficient
photodegradation of direct azo dyes. J. Mol. Catal. A Chem.
258, 124–132.
112
SONDI, I. and SALOPEK-SONDI, B. 2004. Silver nanoparticles
as antimicrobial agent: A case study on E. coli as a model
for Gram-negative bacteria. J. Colloid Inteface Sci. 275,
177–182.
TRAN, M. and FARID, M. 2004. Ultraviolet treatment of orange
juice. Innov. Food Sci. Emerg. Technol. 5, 495–502.
UBONCHONLAKAT, K., SIKONG, L. and KOOPTARNOND, K.
2008. Effect of calcinations temperature on photo catalytic
activity of ag-doped TiO2 coated on tile substrate.
Nanotechnol. 7, 43–50.
VALERO, M., RECROSIO, N., SAURA, D., MUÑOZ, N., MARTÍ,
N. and LIZAMA, V. 2007. Effects of ultrasonic treatments in
orange juice processing. J. Food Eng. 80, 509–516.
XIN, B., REN, Z., HU, H., ZHANG, X., DONG, C., SHI, K., JING,
L. and FU, H. 2005. Photocatalytic activity and interfacial
carrier transfer of Ag–TiO2 nanoparticle films. Appl. Surf. Sci.
252, 2050–2055.
YAM, K.L. and PAPADAKIS, S.E. 2004. A simple digital imaging
method for measuring and analyzing color of food surfaces.
J. Food Eng. 61, 137–142.
YAMAMOTO, O. 2001. Influence of particle size on the
antibacterial activity of zinc oxide. Int. J. Inorg. Mater. 3,
643–646.
YAN, D., YIN, G., HUANG, Z., YANG, M., LIAO, X., KANG, Y.,
YAO, Y., HAO, B. and HAN, D. 2009. Characterization and
bacterial response of zinc oxide particles prepared by a
biomineralizationprocess. J. Phys. Chem. 113, 6047–6053.
ZHANG, H. and CHEN, G. 2009. Potent antimicrobial activity of
Ag/TiO2 nanocomposite powder synthesized by a one-pot
sol-gel method. Environ. Sci. Technol. 43, 2905–2910.
Journal of Food Processing and Preservation 36 (2012) 104–112 © 2011 Wiley Periodicals, Inc.