Study On Nutrition And Edible Quality And Storage Characteristics Of Braised Chicken During Processing

De Zhou braised chicken is one of the typical traditional chicken products in China, and is famous for its fresh meat, mellow flavor at home and abroad. The traditional processing of braised chicken always lack of systematic and scientific data supports, long time cooking caused protein denaturation seriously, even had serious damage to the quality of products, which included decline in nutritional value and texture deterioration of the product. It’s an urgent problem for enterprises to develop delicious, nutritious and healthy braised chicken, and promote the standardization of De Zhou braised chicken.The study has analyzed the changes of nutrients and protein degradation, moisture distribution, the formation mechanism of flavor during cooking braised chicken, and deleloped a new packaging method to improve the eating quality of braised chicken in storage and circulation. The main contents and results are as follows:1. Changes of key nutritional components of braised chicken during processingIt was investigated the changes of moisture, protein, fat, free amino acids (FAA), fatty acid and mineral content in the processing of braised chicken. The results showed that in the processing of braised chicken, the water content declined significantly (p<0.05), the relative content of protein increased whereas the absolute content decreased, and the content of fat showed the highest value after frying process and decreased in cooking process, which demonstrated that the cooking process had great effects on the contents of protein and fat. The level of FAA reduced gradually and, all of it, the arginine content was highest and glutamate, one of umami taste amino acids, also exceeded its threshold, which suggested an significant (p<0.05) effect of salting and cooking on the FAA contents. The ratio of unsaturated fatty acid, which was in favour of human health, over total fatty acids increased during the cooking process. The changes of mineral content were not significant, however, the contents of Na, Cu and Mn increased slightly in the processing of braised chicken. The above results demonstrated that the processing of braised chicken improved the nutritional components, and more over cooking process was the most effective factor on it and salting had little effect on the other nutritional components except of a slight loss of FAA.2.The Changes of Muscle Protein Degradation and Moisture Distribution of braised chicken during processingThe research discussed the changes of production rate, pH, shear force in the processing of braised chicken. And it also studied the changes in myofibrillar protein composition, micro structure and moisture migration laws with techniques of SDS-PAGE electrophoresis, scanning electron microscopy and NMR. The results showed that the production rate of braised chicken after marinated significantly higher than the other stages (p<0.05), the shear force was declined significant (p<0.05) in the processing. SDS-PAGE electrophoresis analysis showed that the myosin heavy chain (MHC), Vice-myosin and actin proteins degraded significantly in the processing, other bands also have degraded in different degree, especially during cooking. Frying caused muscle fibers rupture, large gap and serious water loss, of muscle fibers it showed obvious separation between endomysial and perimysium. The phenomenon of granulated was significant, The diameter of myofibrils declined in the processing, immobilized water downward trend, free water tended to increase, immobilized water changed into free water, water retention was worse. The production rate and shear force and muscle fiber diameter and A22 were significantly positive correlated (p<0.05), shear force and muscle fiber density was significantly negative correlated (p<0.05), production rate and muscle fiber density was negatively correlated but not significant (p>0.05).3. The Changes of Flavor Compounds in Braised Chicken During Recycling UseThe non-volatile and volatile flavor compounds in braised chicken and marinating liquid were detected using liquid chromatograph, high performance Liquid chromatograph and headspace solid-phase micro-extraction combined with gas chromatography-mass spectrometry (SPME-GC-MS) in order to investigate the changes of non-volatile and volatile flavor compounds in braised chicken leg during recycling use of marinating liquid. The experimental groups were braised in the marinating liquid which was boiled with fresh chicken from 0 to 5 times, and the control group was cooked with distilled water. The results showed that free amino acids and nucleotides contents in the control group and the experimental groups which braised from 0 to 6 were significant increased. The amount of volatile compounds were 15,27,29,30, 32,27 and 25 in the control group and the experimental groups which braised from 0 to 6 times. The peak numbers of volatile flavor compounds were the most and the peak area was the largest in the experimental group by cooking at 4 times.4.The quality changes of braised chicken during refrigeration in package without removing sealing film and suitable for microwave heating.Braised Chicken was packed with different ways of packaging. In order to study the effect of without removing sealing film and suitable for microwave heating packaging material during storage, physical and chemical indicators of braised chicken, such as pH value, total volatile basic nitrogen (T-VBN), microbial counts, surface color changes, and sensory evaluations were conducted. The results indicated that pH value significant decreased (p<0.05) during storage, for without removing sealing film and suitable for microwave heating packaging, the T-VBN values were more than 20mg/100g after 9 days, but after 18 d the TVB-N content of chitosan treatment group was just 16.5mg/100g. The shelf-life of the product without removing sealing film was 9 d, the vacuum packaging group reached 14 d. In the 18 d, the CFU of chitosan group was only 4.79 1g, which has not yet reached the national standard limit. L* and b* value of Vacuum packaging samples were significantly lower than the groups of without removing sealing film (p<0.05), while a* value was significantly higher than the groups of without removing sealing film and suitable for microwave heating packaging (p<0.05).