Study On Quality Change Of Stewed Pork During Processing And Storage

Chinese cuisine is an important part of traditional Chinese food,however,currently most of it can only be served in the family or restaurant,which makes it difficult to meet the fast pace of modern life.Traditional Chinese cuisine is developed into prepared convenience dishes and its shelf life is extended by modern food processing and preservation technology to make it more convenient and fast-eating,which is the development trend of Chinese cuisine in the future with broad application prospects.In this paper,the popular Chinese cuisine stewed pork was studied.The quality change during the processing of stewed pork dishes and the way to prolong its shelf life were studied,as well as the product hygienic quality standard was established to lay the foundation of standardized and large-scale manufacturing and quality control of the product.Firstly,the quality change during the processing of stewed pork dishes was studied.The physicochemical indices,fat oxidation and flavor change of stewed pork during the processing stage of pre-cooked for 5 min,stewed for 30 min,60 min,90 min were monitored.Results showed that the moisture content decreased by 17.53% compared with that of raw material,and the fat content decreased.The color and texture characteristics of the lean and fat layers were gradually formed and kept in a good range.TBA showed an upward trend with a final value 0.42 mg MDA/kg;POV increased first and then decreased;cholesterol content decreased.Palmitic acid(C16: 0),stearic acid(C18: 0),oleic acid(C18: 1)and linoleic acid(C18: 2)were main fatty acids in stewed pork,and the fatty acid composition after processing were changed.A total of 129 kinds of volatile flavor compounds were detected during the processing of stewed pork.The number of flavor compounds in the product was up to 65 and the total content was 1948.93 ?g/kg.The types and contents of various flavors in the processing of stewed pork were significantly changed.The correlation analysis results showed that aldehydes and ketones,alcohols,heterocycles and other compounds as well as hydrocarbon compounds were the main contributing components of the volatile aroma compounds of stewed pork dishes.Secondly,the packaging methods of stewed pork convenience dishes were studied.Total number of colonies,TVB-N,TBA,pH,moisture content,color difference and sensory evaluation were determined and analyzed on stewed pork convenience dishes stored under different packaging environments at 4°C.Results showed that both modified atmosphere packaging(35% CO2+65% N2)and vacuum packaging could effectively retard the quality change of the product during storage,and extend the shelf life from 6~9 to 12~15 days.Vacuum packaging and modified atmosphere packaging were found to show no significant differences in physicochemical parameters determined instrumentally,while modified atmosphere packaging performed better in sensory quality control.Finally,the effect of secondary low-temperature sterilization on further prolonging the shelf life of stewed pork convenience dishes product was studied.The effects of 80~85°C for 10 min,80~85°C for 30 min,90~95°C for 10 min and 90~95°C for 30 min on the product quality and shelf life were compared.Results showed that the optimum secondary sterilization parameter was 80~85°C for 30 min considering all indices.80~85°C for 30 min sterilization could effectively kill the vast majority of microorganisms of product during cooling and packaging process and basically retain the original sensory quality and texture,color and flavor characteristics of product.The shelf life was obviously extended.Combined with sensory evaluation the safe shelf life of stewed pork convenience dishes product was 4 weeks at 4°C storage.The microbial safety and all other qualities of the product during the shelf life were in line with national standards and commercial circulation requirements,which improved the added value of convenience dishes food products.