الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Freshwater crayfish has been considered as seafood for several years, especially in the state of Louisiana, USA. The total annual global harvest of fresh water crayfish is more than 110,000 tons, where USA produces 55% of this quantity, followed by China, which produces 36%. Industrial utilization of freshwater crayfish began in Louisiana where its meat is processed by boiling in water, then it is manually peeled and flesh parts are packaged and stored under cold conditions.
Egypt has only two species of crayfish in the River Nile which they introduced in the early 1980’s; Procambarus zonagulu and Procambarus clarkii where the latter is the most prevalent specie.
This study aims to take advantage of crayfish found in River Nile, which does not have acceptance from the Egyptian consumers in the fresh state for manufacturing of certain fish products, which include (canned crayfish - crayfish burger). The study also aims to use the resulting waste in getting some vital compounds such as chitosan and carotenoids, which increases the quality of the product.
The study was carried out through the following points
1. Studying the chemical composition of crayfish in comparison with shrimp.
2. Studying the chemical composition of crayfish wastes.
3. Extraction of chitosan and carotenoids from crayfish wastes and studying their physicochemical and functional properties.
4. Studying the antioxidant activity of extracted chitosan and carotenoids.
5. Manufacturing of crayfish products such as canned and crayfish burger with different treatments.
6. Studying the quality characteristics of crayfish products as affected by addition of chitosan and carotenoids as well as storage period.
The obtained results could be summarized as follows:
1. The results of chemical, physicochemical and microbiological analysis, for both of freshwater crayfish and shrimp: indicated that the flesh of crayfish contained a 76.81% moisture, 19.18% protein, 1.95% fat, 1.49% ash, 0.57% carbohydrates. For the physicochemical properties 4.06 TVBN, 0.63 TMAN, Microbial content 5.324 Log 10 CFU / g TBC, and pH 6.97. While the shrimp meat contained 76.38% moisture, 19.53% protein, 1.86% fat, 1.55% ash, 0.68% carbohydrates, 4.68 TVBN, 0.79 TMAN, 5.892 Log 10 CFU / g TBC and pH 6.86.Crayfish wastes contained 63.80% moisture, 9.24% protein, 3.25% fat, 11.07% ash, 12.64% carbohydrate.
2. Chemical composition and physicochemical and functional properties for both extracted and commercial chitosan show higher content of moisture, total nitrogen, ash, Degree of Deaceteylation (DDA), solubility in commercial chitosan when compared with extracted one, while extracted chitosan had increase in its ability to bind both oil and water compared to commercial one.
3. The antioxidant activity of the extract chitosan was higher than that of commercial chitosan and carotenoids.
4. Food Applications:
(A) - canning:
1. Canned crayfish: where crayfish meat has been canned by four different treatments as follows:
First,canned crayfish by adding brine, 10% sunflower oil, which represents a baseline sample (Control);second canned crayfish under the same conditionsand adding 0.5% carotenoids to the canning mixture;third canned crayfish by adding spice mixture of concentration of 1g and fours canned crayfish at the same conditions after soaking in a smoking liquid. Canned shrimp by adding brine, 10% sunflower oil which represents the control treatment.
All previous treatments were stored at room temperature 25±5°C and samples were analyzed every 30 days for six months.
1. By studying the chemical composition, it was observed that there was a gradual decline in moisture, protein and fat in all treatments through the different periods of storage, and the highest rate of decline was in the control sample, followed by treatment of a mixture of spices. While, there was a gradual increase in the ash in all treatments and the highest rate was in canned shrimp then in the treatment of carotenoid.
2. All treatments characterized by stable quality standards during the storage period and were within the limits. While, for color, its density decreased gradually in all treatments except in case of canning treatment using carotenoid where the decline in the color did not notice.
3. By studying ranciditystandards, which include: - acid value, peroxide value, anisidene value and total oxidation, results indicated an insignificant increase in the all previous parameters of lipids extracted from the samples during different storage periods and all measures were below critical levels. All treatments showed confirmed high degree of stability against rancidity factors during different storage periods and even after the sixth month of storage.
4. The results showed that there is slightly increase in the logarithm of the number of bacteria during storage at room temperature 20 °C for 6 months in all canning treatments. The most increased treatments in the total number of bacteria during storage are canned shrimp then control canned crayfish sample, followed by canned crayfish using a mixture of spices. The highest bacterial spores during storage at room temperature was recorded in canned crayfish using a mixture of spices, then canned shrimp, followed by the control sample.
5. The obtained results showed that sensory evaluation of the samples of canned shrimp and crayfish by different treatments had high degree of consumer acceptance and the properties of color and quality were improved by adding carotenoid, but the canned smoked crayfish had not acceptance degree of consumer.
(B) –Crayfish burger treatments:
Manufacture crayfish burger products by four different treatments. First, crayfish burger without additives (control); Second,burger plus 0.5% chitosan extracted from the wastes of crayfish;Third,burger plus 0.5% commercial chitosan and fourth, Burger plus 0.5% carotenoids extracted from the wastes of crayfish.
All previous treatments had been frozen and then stored at a temperature of -18° C for 3 months and samples were analyzed every 15 days.
1. Adding 0.5% chitosan (extracted or commercial) and carotenoid to crayfish burger treatments reduced rate of loss of moisture, protein, fat and increased content of ash during frozen storage at -18 °C for 3 months, and the highest rate of increase of ash was recorded in the carotenoid treatment followed by commercial chitosan treatment and extracted chitosan treatment.
2. Physiochemical analyses such as pH, TVB-N, TMA-N of burger treatments showed that the addition of 0.5% chitosan (extracted or commercial) and carotenoid led to maintain product quality and reduce the rate of increase in above parameters of the three treatments compared to the control during frozen storage for a period of three months.
3. The obtained results for the intensity of color in the samples showed that the best burger treatments are that where 0.5% added carotenoid when compared to other treatments.where the low decline rate of color intensity during frozen storage for a period of three months was recorded in the carotenoid treatment when compared to other treatments.
4. The addition of 0.5% chitosan (extracted or commercial) and carotenoids improved the efficiency of the correlation with water in the product. Efficiency correlation with water increased better in the treatment of extracted chitosan compared to the control sample.
5. Cooking loss rate by decreased by adding 0.5% chitosan (extracted or commercial), while increasing the proportion of cooking loss during frozen storage was more seen in the control treatment and carotenoid.
6. The results showed that adding 0.5% chitosan (extracted or commercial) and carotenoid improved degree of stability against oxidation and rancidity of lipids extractedfrom the samples during frozen storage.
7. The addition of 0.5% chitosan (extracted or commercial) and carotenoid to freshwater crayfish burger samples decreased the logarithm of the number of bacteria and coliform bacteria during frozen storage.
8. The results showed that the addition of 0.5% chitosan (extracted or commercial) and carotenoid improved sensory characteristics of the cooked crayfish burger samples by grilling method when compared to the control.
Finally, it could be concluded the following findings:
1. Crayfish it is characterized by high content of protein and fatty acids, especially omega-3 and mineral elements, which match the nutritional value of the most important commercial crustaceans asshrimp.
2. The crayfish was manufactured in the canned image the results indicated that the best treatments for the production of the crayfish on this picture are the canned crayfish with the addition of carotenoids extracted from the crayfishwastes by 0.5%,this improved the color and the sensory properties.
3. Crayfish was manufactured in the form of burger the results indicated that the best treatments for the production of crayfish on this picture arecrayfish burger, which is added to the chitosan powder and carotenoids extracted from the crayfish wastes by 0.5% the result is improved by physicochemical, microbiological and sensory properties.
4. It was possible to take advantage of the industrial of crayfish wastes in the extraction of some vital compounds such as chitosan and carotenoids and was evaluated for use in the processes of the manufacture of canned crayfish and crayfish burger proved to be good natural materials and high efficiency as antioxidants and antimicrobial growth.