الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
combination of materials of various chemical natures and physical structures, are used to
fulfill the functions and requirements of pa32ckaged foods depending on their type.
However, there has been ever increasing effort in the development of different kinds of
packaging materials in order to enhance their effectiveness in keeping the food quality with
improved convenience for processing and final use.
Among the four basic packaging materials, petroleum-based plastic materials have
been widely used since the middle of the twenties century. It is mainly because they are
cheap and convenient to use with good processing property, good aesthetic quality, and
excellent physico-chemical properties. More than 40% of the plastics are used for
packaging and almost half of them are used for food packaging in the form of films, sheets,
bottles, cups, tubs, and trays, etc.
After their useful life, it is desirable for the packaging materials to biodegrade in a
reasonable time period without causing environmental problems. Though the synthetic
plastic packaging materials have been widely used for the packaging of various types of
food, they caused a serious environmental problem since they are not easily degraded in
the environment after use.
The present study aimed to investigate challenges and opportunities to increase the
shelf-life of some packaged food using polymeric nanofibers incorporated with
antimicrobial agents.
To fulfill this aim, the following has been adapted:
I. Nanofiber preparation
1. Nanofiber with imbedded chitosan
1. 2 layers of Polyvinyl Chloride (PVC)/THF+DMF polymers were electrospun.
2. Chitosan was evenly spread in-between the 2 PVC fibers.
3. A total of 6 Nanofiber sheets were synthesized.
4. Fibers were observed using a scanning electron microscope (SEM).
2. Nanofiber impregnated in chitosan solution
Nanofiber was soaked in chitosan blend for 1 hour then left to dry for 24 hours. The
same step is repeated to the other face of the fiber.
3. Scanning Electron Microscopy (SEM)
Nanofibers were characterized using Scanning Electron Microscope (SEM) to detect
the most suitable polymer according to fiber’s diameter average, homogeneity and
uniformity.
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II. Preparation of the samples:
1. Meat:
A total of 0.5 kg of fresh meat was purchased from local market and transferred to
the laboratory in cold condition.
The meat was divided into 10 samples 20 gm for each. 5 samples were covered with
cling film and 5 samples were covered with nanofiber. All samples were stored in
refrigerator temperature.
Meat samples were examined 3 times with an interval of a week for physical,
microbiological and chemical tests.
2. Fish:
Two types of fresh fish, Tuna fish weigh 200 gm and Perch fresh weigh 180 gm were
purchased from local market.
Each type of fish was divided into 8 samples 20 gm for each. 4 samples were covered
with cling film and 4 samples were covered with nanofiber. All samples were stored in
refrigerator temperature.
The samples were examined for physical, microbiological and chemical for 2 times,
by the purchase date and after the expiry date.
3. Cheese:
A Domti® package of 1 kg fresh low salt white cheese was purchased from local
market. The package was transferred to the laboratory in cold condition.
The cheese was divided into 16 samples 20 gm for each.
The cheese samples were examined in two different nanofibers. Nanofiber imbedded
with chitosan packaged samples and Nanofiber impregnated in chitosan packaged samples.
The samples were examined for physical, microbiological and chemical for 2 times,
by the purchase date and after the expiry date.
III. Physical evaluation
Samples were examined for appearance, discoloration, texture and odor over the
study time range organoleptically.
IV. Microbiological examination
1. Total aerobic mesophilic plate count.
2. Enumeration of Coliform (Most Probable Number, MPN)
3. Detection of fecal coliform.
4. Isolation of coagulase and Dnase positive Staphylococci.
5. Mold and yeast.
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V. Chemical analysis
Analysis of ash, moisture, carbohydrates, protein and fat.
Results were as follows:
1. Physical analysis:
About the raw meat, there is no change shown in colour, texture and odour in 7th and
12th days of storage of nanofiber packaged raw meat. While Cling film packaged raw meat
at 12th day showed changes in colour because of growth of microorganisms and showed
dehydration and the cling film packaged raw meat was off odour.
Concerning Tuna fish, at the 3rd day, there is a change in cling film packaged raw
tuna fish shown in colour (dark red colour), texture (softening texture) and odour (offodour).
While the nanofiber packaged raw tuna fish showed no change through the storage
time.
While in Perch fish, at the 3rd day, there is a change in cling film packaged raw perch
fish shown in colour (greenish red colour), texture (softening texture) and odour (offodour).
While the nanofiber packaged raw perch fish showed no change through the
storage time.
On the other hand and in low salt white cheese covered with in-between chitosan
nanofiber, . At the 15th day, there is no change in colour in both nanofiber packaged lowsalt
white cheese and cling film packaged low-salt white cheese. While there is a change in
cling film packaged low-salt white cheese shown in texture (hardness texture) and odour
(rancid odour). While the nanofiber packaged low-salt white cheese showed no change
through the storage time.
And in nanofiber impregnated in chitosan solution, at the 15th day, there is no change
in colour in both nanofiber packaged low-salt white cheese and cling film packaged lowsalt
white cheese. While there is a change in cling film packaged low-salt white cheese
shown in texture (hardness texture) and odour (rancid odour). While the nanofiber
packaged low-salt white cheese showed no change through the storage time.
At the 21st day, there is a change in colour (yellowish colour) in cling film packaged
low-salt cheese while the fresh white colour is still in nanofiber packaged low-salt white
cheese at 21st day. While there is a change in cling film packaged low-salt white cheese
shown in texture (hardness texture) and odour (rancid odour) at 21st day. While the
nanofiber packaged low-salt white cheese showed no change through the storage time.
2. Microbiological
Nanofiber inhibited the growth of mesophilic count at 12th day that shows the
nanofiber wrapped meat was 1.4x10٧ CFU/g, while cling film packaged meat was 3.8x107
CFU/g. Coliform count decreased in meat packaged in nanofiber as that in 12th day
coliform count in nanofiber packaged meat was 210 MPN/g, while it was >1100 MPN/g in
cling film packaged meat.
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Staphylococci count at 12th day shows lower count in nanofiber packaged meat
(2.2x104 CFU/g), while in cling film packaged meat was 3.2x105 CFU/g.
Concerning mold and yeast at 12th day, there was no significant variation in their
counts among the cling film packaged meat (2.9x107 CFU/g) and nanofiber packaged meat
(3.1x106 CFU/g).
Nanofiber inhibited the growth of mesophilic count at 3rd day that shows the
nanofiber wrapped raw tuna fish was 1.9x105 CFU/g, while cling film packaged meat was
6.2x105 CFU/g. Coliform count decreased in raw tuna fish packaged in nanofiber as that in
3rd day coliform count in nanofiber packaged tuna was 20 MPN/g, while it was >1100
MPN/g in cling film packaged raw tuna fish.
Staphylococci count at 3rd day shows lower count in nanofiber packaged raw tuna
fish (2.2x104 CFU/g), while in cling film packaged raw tuna fish was 3.2x105 CFU/g.
Concerning mold and yeast at 3rd day, there was no significant variation in their
counts among the cling film packaged meat (2.9x107 CFU/g) and nanofiber packaged raw
tuna fish (3.1x106 CFU/g).
Nanofiber inhibited the growth of mesophilic count at 3rd day that shows the
nanofiber wrapped raw perch fish was 2.25x105 CFU/g, while cling film packaged raw
perch fish was 2.7x105 CFU/g. Coliform count decreased in raw perch fish packaged in
nanofiber as that in 3rd day coliform count in nanofiber packaged raw perch fish was 210
MPN/g, while it was >1100 MPN/g in cling film packaged raw perch fish.
Staphylococci count at 3rd day shows lower count in nanofiber packaged raw perch
fish (1.5x10٥ CFU/g), while in cling film packaged raw perch fish was 1.2x104 CFU/g.
Concerning mold and yeast at 3rd day, there was a significant variation in their counts
among the cling film packaged raw perch fish (1.02x104 CFU/g) and nanofiber packaged
raw perch fish (4.5x106 CFU/g).
Nanofiber with imbedded chitosan inhibited the growth of mesophilic count at 15th
day that shows the nanofiber wrapped low-salt white cheese was 1.2x104 CFU/g, while
cling film packaged low-salt white cheese was 3.1x103 CFU/g. Coliform count decreased
in low-salt white cheese packaged in nanofiber as that in 15th day coliform count in
nanofiber packaged low-salt white cheese was 15 MPN/g, while it was 29 MPN/g in cling
film packaged low-salt cheese.
Staphylococci count at 15th day shows lower count in nanofiber packaged low-salt
white cheese (4.8x103 CFU/g), while in cling film packaged low-salt white cheese was
2.25x104 CFU/g.
On the other hand, cling film packaged low-salt white cheese shows the highest mold
and yeast count at 15th day (2.9x107 CFU/g) while nanofiber packaged low-salt white
cheese was 3.1x106 CFU/g.
Nanofiber impregnated in chitosan solution, inhibited the growth of mesophilic count
at day 21st that shows the nanofiber wrapped low-salt white cheese was 0.78x104 CFU/g,
while cling film packaged low-salt white cheese was 2.2x104 CFU/g. Coliform count
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decreased in low-salt white cheese packaged in nanofiber as that in 21st day coliform count
in nanofiber packaged low-salt white cheese was 9 MPN/g, while it was 39 MPN/g in cling
film packaged low-salt cheese.
Staphylococci count at 21st day shows lower count in nanofiber packaged low-salt
white cheese (4.8x103 CFU/g), while in cling film packaged low-salt white cheese was
2.25x104 CFU/g.
On the other hand, cling film packaged low-salt white cheese shows the highest mold
and yeast count at 21st day (3.1x105 CFU/g) while nanofiber packaged low-salt white
cheese was 1.7x104 CFU/g.
The microbial load of different nanofibers packaged food items depends upon the
initial microbial load, sanitary conditions, time and temperature of storage. The mentioned
storage parameters have been found to affect the initial microbial load. (132)
Results of the total aerobic mesophilic count showed that the most responded food
item to the nanofiber wrapping was reported in the raw tuna fish at the 3rd day (1.9x105
CFU/g), starting at 1st day with microbial load (3.0x104 CFU/g). While the least responded
food item to the nanofiber wrapping was noticed in the raw perch fish at the 3rd day
(2.25x105 CFU/g), starting at 1st day with microbial load (1.1x103 CFU/g).
The initial coliform bacterial count of cling film wrapped raw meat at the 1st day was
(244 MPN/g), which shows high decline in the nanofiber packaged raw meat at the 12th
day (210 MPN/g).
Concerning low-salt white cheese, there is a quite insignificant decline in the
staphylococci count comparing between nanofiber packaged cheese at 1st day (2.4x104
CFU/g) and nanofiber packaged cheese at 21st day (4.8x103 CFU/g).
3. Chemical
Concerning the protein content at 12th day, it was 21.٢٥٠% in nanofiber packaged
raw meat and 24.180% in cling film packaged raw meat. The carbohydrate content at 12th
day of cling film packaged raw meat was 1.848% and it was 0.722% in nanofiber packaged
raw meat. Fat content was 1.25% in cling film packaged raw meat, while it was 1.50% in
nanofiber packaged raw meat. The difference between cling film wrapped raw meat and
nanofiber wrapped raw meat is insignificant.
The ash content in 3rd day of nanofiber packaged raw tuna was 1.2% while it was
1.5% in cling film packaged raw tuna fish.
The table shows a higher loss of moisture content in the cling film packaged raw tuna
fish at the 3rd day (50.0%) in comparison to the nanofiber packaged raw tuna fish (51.2%).
Concerning the protein content at 3rd day, it was 31.1% in nanofiber packaged raw
tuna fish and 30.3% in cling film packaged raw tuna fish. The carbohydrate content at 3rd
day of cling film packaged raw tuna fish was 11.4% and it was 12.6% in nanofiber
packaged raw tuna fish. Fat content was 0.2% in cling film packaged raw tuna fish, while it
was 0.3% in nanofiber packaged raw tuna fish.
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The ash content in 3rd day of nanofiber packaged raw perch fish was 1.4% while it
was 1.6% in cling film packaged raw perch fish. The moisture content was 49.7% and
48.2% in nanofiber packaged raw perch fish and cling film packaged raw perch fish
respectively.
Concerning the protein content at 3rd day, it was 28.3% in nanofiber packaged raw
perch fish and 27.2% in cling film packaged raw perch fish. The carbohydrate content at
3rd day of cling film packaged raw perch fish was 17.1% and it was 16.5% in nanofiber
packaged raw perch fish. Fat content was 0.8% in cling film packaged raw perch fish,
while it was 0.7% in nanofiber packaged raw perch fish.
It is recommended to:
1. Find of low cost technologies for chitosan-based active films preparation is a key
for the success of this unique biopolymer as a real packaging material.
2. There is an urgent need for informed public debate on nanotechnology and food.
3. Nanotechnology can be applied in all aspects of the food chain, both for
improving food safety and quality control, and as novel food ingredients or
additives.
4. As developments in nanotechnology continue to emerge, its applicability to the
food industry is sure to increase. The success of these advancements will be
strictly dependent on exploration of regulatory issues.
5. Assess potential risks related to certain food-related uses of nanotechnology.
6. Assess applications from industry to use engineered nanomaterials (ENMs) in
food additives, enzymes, flavorings, food contact materials, novel foods, food
supplements, feed additives and pesticides.
7. Regulating the use of nanocomponents and nanoscale equipment in food.
8. Research into the consequences of the ingestion of nanoparticles.
9. Inspect food labeling to identify the presence of nanomaterials in products and
provide possible particle size range and relevant safety information.