| Braised pork in brown sauce is one of the Chinese traditional meat dishes because of its cultural heritage,exquisite cooking skills,unique flavor,nutrient-rich and so on.To the traditional process of braised pork in the processing of lean meat fleshy dry wood,serious loss of juice,low yield and other technical bottlenecks as the guide,to explore the appropriate quality improvement methods.In addition,the quality characteristics and ultrastructural changes of the product were investigated when the chain was broken in the cold chain logistics distribution process.Finally,the changes of amino acid composition during the processing of braised pork was studied,and the nutritional value of the protein was evaluated.The purpose of this project is to provide new ideas and technical support for new product development and quality improvement of braised pork,and to guide the healthy and nutritious diet and life of consumers.The researches content as follow:1.The objective of this study was to investigate the effect of different brining crafts on braised pork in brown sauce quality.Injection brining(IB-test group 1)and pressure varied static brining(PVSB-test group 2)with no brining(NB-control 1)as the control were employed to prepare cured meat.The quality indexes of samples including water content,salt content,fat and protein content,pH,shear force,cooking loss,T2 relaxation and microstructure.Results showed that after curing,the group 2 absorption rate is significantly higher than group 1(p<0.05).Moisture of the intermediates and braise in soy sauce pickle products,production rate increased significantly(p<0.05),and two kinds of curing methods are of different level to improve its color,quality and structure,tenderness,and other quality characteristics,improve the quality of products.Pickled intermediates and finished product pH after curing to braise in soy sauce and salt content are rising,and a significant difference between experimental group and control group(p<0.05),of which the group 2 of pH and salt content is the highest.From raw materials to souse hind intermediates and salted meat braise in soy sauce after finished product,water loss rate and loss rate of centrifugal significantly reduced(p<0.05).Low field nuclear magnetic resonance(LF-NMR)T2 relaxation time test results show that after curing of raw meat,not easy to flow water content significantly increased(p<0.05),and the group 2 is not easy to flow water content significantly higher group 1(p<0.05).The results of scanning electron microscopy showed that the finished fabric was cured and the fiber structure was damaged,and the structure of the static varnish was more loose and the fibrous tissue gap was the largest,which was beneficial to improve the water retention.Static varnish can effectively improve the quality of pork processing,to improve the processing technology to provide a theoretical support.2.The objective of this study was to investigate the effect of the freezing and thawing cycles on its quality characteristics and the influence of the ultrastructure and change rule on nursing braise in soy sauce meat products cold-chain logistics distribution process.The micro-self-heating packaging regulate braise in soy sauce meat was used as the research material.The edible and nutritive quality(water content,thawing juice loss rate,pH value,thiobarbituric acid)in the process of freeze-thaw cycle were analyzed by modern food instrumentation by simulated freezing and thawing 0,1,3,5,7 times(TBA),fat content,color,shear strength and texture characteristics),total number of colonies,flavor,water status and ultrastructural changes.Conclusion: when the number of freeze-thaw cycles increased,the water content of the tuned pork was significantly decreased(p<0.05),and the loss of thawing juice was significantly increased(p<0.05),indicating that the water retention of the product decreased(p>0.05),but decreased with freezing and thawing cycles(p<0.05),which indicated that the nutrient loss was serious.The pH value showed a significant decrease(p<0.05).L* and b* were gradually increased,and the value of a* was significantly decreased(p<0.05),which indicated that the pork was gradually lost after repeated freezing and thawing(p>0.05),and the rate of TBA was significantly increased(p<0.05).Compared with the control group,the shear force value was increased and decreased,and the shear force was slightly decreased after freezing and thawing.The shear strength,elasticity,cohesion and chewiness were significantly different(p>0.05),but the shear force decreased significantly after freeze-thawing to the 7th day(p<0.05).The total number of colonies in the product freeze-thaw 5 times,has exceeded the national limit(8×104 CFU/g).Electronic nose can distinguish between different freezing and thawing stage of the pork,and the difference in flavor is mainly reflected in hydrogen sulfide and nitrogen oxides.The results of LF-NMR T2 relaxation time showed that the relaxation time T22 and T23 were significantly decreased(p<0.05),and the flowable water content was significantly decreased(p<0.05)when the number of freeze-thaw cycles increased.Scanning electron microscopy(SEM)analysis showed that the meat-like structure changed obviously after the freeze-thaw cycle,the intimal rupture,the intercellular space of the muscle fibers increased and the structure was chaotic.Freeze-thaw cycle led to the improvement of the consumption of pork and the nutritional quality of serious deterioration,ultrastructure is also destroyed,it should improve the cold chain logistics system engineering,to avoid cold chain logistics and distribution process of temperature fluctuations in a wide range.3.Changes of the amino acid nutritional quality in the stewed pork in brown sauce during processing.Conclusion: The total amount of amino acids in braised pork was 17.60%,and the content of glutamic acid was the highest,which was 2.95%.The proportion of essential amino acids was 41.02% and the ratio of amino acids was 39.66%.Therefore,braised pork is a high quality protein source and delicious meat.The amino acid score of lysine is the highest,the chemical point indicates that egg+cystine is the first limiting amino acid,and styrene-acrylic acid tyrosine is the second limiting amino acid.Therefore,when eating braised pork and egg and cysteine rich in content,lysine relative lack of food to match,in order to maintain a balanced diet and nutrition. |
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