Abstract: Fermented sausages were manufactured with a mixed starter culture of Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201, and naturally fermented samples were used as a control. We investigated protein degradation in fermented sausages by the mixed starter culture by determining physicochemical properties, performing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and measuring peptide content, and free amino acid content. In vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cation scavenging and ferric ion reducing antioxidant power (FRAP) assays were used to evaluate the antioxidant capacity of crude peptides and peptide fractions with molecular mass lower than 3 kDa extracted from fermented sausages. The results showed that the content of non-protein nitrogen in the inoculated group was significantly higher than that in the control group (P < 0.05). According to the results of SDS-PAGE, both sarcoplasmic and myofibrillar proteins were degraded in the two groups, and the degree of protein degradation in the inoculated group was higher than that in the control group, notably the accumulation of bands with a molecular mass of less than 20 kDa. The DPPH radical scavenging activity, ABTS radical cation scavenging activity and FRAP value of crude peptides and small molecular peptides extracted from the inoculated group were significantly higher than those in the control group (P < 0.05). The small molecular peptides may be the main contributor to the antioxidant capacity of the peptides extracted from fermented sausages. The release of free amino acids from fermented sausages was promoted by the mixed starter culture. This mixed starter culture could promote protein degradation in fermented sausages to produce more peptides with antioxidant activity, helping inhibit fat oxidation in fermented sausages and thereby reducing the production cost and prolonging the shelf life.

Key words: stability; antioxidant peptides; fermented sausages