Abstract:

The relationship between protein degradation and quality of fermented sour meat was investigated by analyzing the environmental factors, the lactic acid bacteria number and the degraded products of protein in sour meat during fermentation. The results indicated with the increasing fermentation time, the contents of protein, myofibril protein and myosinogen reduce while the content of non-protein nitrogen (NPN) increases. The intermediate products of protein degradation including peptide nitrogen and amino acid nitrogen increase at first and then fall down. The content of total volatile basic nitrogen is 19.56 g /100 g sour meat fermented for 60 d. Analysis on amino acid composition showed that the amino acid score increases during fermentation. The contents of protein, myofibril protein and myosinogen are conversely linked to lactic acid bacteria number or NaCl content, but positively to activity of water (Aw) or pH value. However, the changes of NPN show a different pattern and positively related to the lactic acid bacteria number or NaCl content, but negatively related to Aw or pH value. In this regard, the nutritive value of protein in sour meat can be improved by fermentation and the best fermented time of sour meat is suggested to be between 20 d and 40 d when considering safety and flavour of sour meat.

Key words: sour meat, environmental factors, protein, nutritive value