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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. Summary 77 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. Summary 78 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. Summary 79 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 Summary 80 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. Summary 81 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. |