Studies On The Effects Of Muscle Proteolytic Enzymes In The Processing Of Jinhua Ham

Jinhua ham is representative of traditional Chinese meat products and is one of the famous dry-cured hams of the world. However, the laggard processing technology primarily adopted in small-scale workshops has become a great hazard limiting its development. In fact, the key parameters used in traditional Jinhua ham processing technology are still not concrete and little work has been done on the research of its processing theory up till now. This research is a part of a National 863 Program item entitled "Producing technology and products exploitation for Chinese traditional & character food and animal products". The aim is to investigate the changes of muscle proteolytic enzyme activities and their influencing factors, after clarifying the processing parameters of the traditional processing technology, study the rules of muscle proteolysis and the formation of flavor substances, and finally elucidates the roles of muscle proteolytic enzymes in the processing of Jinhua ham.By experiment design, the research comprises three parts. The first, study of the processing parameters of traditional Jinhua ham processing technology and its optimization. The second, time-related changes of muscle proteolysis, proteolytic enzyme activities and flavor substances during processing of Jinhua ham. The third, factors influencing muscle proteolytic enzyme activities and changes of the actual activities of the enzymes. The contents and results are as follows. Optimization of traditional Jinhua ham processing technology and correlation analysis on its main technological parametersSix factors and 3 levels optimization experiment design on the traditional processing technology of Jinhua Ham was performed using DOE Custom Design program of JMP software. Experimental Jinhua Hams were processed according to the design with 144 fresh hams from local cross pigs of Lanxi, Zhejiang province, China. Taking sensory evaluation data of the experiment hams after aging and after post-aging as responses, the experiment data were analyzed by JMP variance analysis program, and correlation analysis was also performed on main technological parameters and sensory evaluation data using SPSS. Theresults showed that salting time, soaking time and ham hanging position in aging-loft were the important factors influencing product quality and the optimum technological combination was salting 30d, soaking 18h and aging in a climate similar to that around the upper ham position in the aging-loft. Fresh ham weight, salt dosage, total ham weight loss after each processing stage and product sensory characters were significantly correlated (P<0.05). According to the results, when processing Jinhua ham with green hams from cross pigs, weight losses after salting, sun-drying and loft-aging should not be less than 11%, 19% and 36% respectively. Time-related changes of muscle proteolysis during Jinhua ham processingExperimental Jinhua hams were processed according to traditional processing technology with 60 local cross green hams weighted 6.2 to 6.9 kg. Biceps femoris samples from 5 hams each time were taken on 1 d. 31 d, 51 d, 124 d, 203 d and 264 d and muscle proteolysis indices were analyzed. The results showed that muscle proteins, especially water-soluble proteins were hydrolyzed continuously during processing of Jinhua ham and small molecular products such as peptides and free amino acids (FAA) were generated. At the end of processing, the proteolytic index (P. I. %) of Jinhua ham was 14 to 20.Each processing stage had its characteristic in muscle proteolysis. The most intense proteolysis process happened at sun-drying stage, followed by the first half of loft-aging and post aging stages. Salting stage was characterized by hydrolyzation of water-soluble proteins and peptides smaller than 1 kDa, while almost all proteins and peptides larger than 1 kDa were hydrolyzed to some extent and smaller peptides than 1 kDa generated during the first half of lost-aging period. The second half of loft-aging was characterized by changes of non-protein nitrogen (NPN) components tha...