Effects of Different Protease-Producing Lactic Acid Bacteria on the Degradation of Dried Beef Protein

In order to improve the quality of dried beef products, the impact of protease-producing lactic acid bacteria on the degradation of beef protein was clarified. Three lactic acid bacteria (LAB) strains with high protease-producing ability were inoculated in the dried beef, namely Lactococcus lactis (S-1), Lactococcus gracilis (S-2) and Pediococcus pentosaceus (S-3). The samples without adding starter were used as control group (CK). Instrumental analysis and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were used to detect the protein degradation of dried beef. The results showed that the contents of non-protein nitrogen, amino acid nitrogen and TCA-soluble peptide increased gradually with the extension of fermentation time, and the inoculation group was significantly higher than the CK group (P<0.05). The contents of non-protein nitrogen, amino acid nitrogen and TCA-soluble peptide of protease-production LAB S-1 and S-2 were significantly higher than those of S-3 group (P<0.05). The content of amino acid nitrogen in each group increased, and the amino acid nitrogen in S-1 group increased the most, reaching 577.68 mg/100 g, but there was no significant difference between the inoculation groups (P > 0.05). The total free amino acids in the samples of S-1 and S-2 groups were significantly increased (P < 0.05). SDS-PAGE results showed that the protein degradation degree of the inoculation group was significantly higher than that of the CK group. In the process of dried beef production, inoculation of protease-producing lactic acid bacteria could significantly improve the degree of protein degradation, and S-1 group had the most obvious effect on protein degradation.