Exploring in vitro digestibility of proteins in fresh pork and Chinese sausages: Effects of Staphylococcus carnosus RT6 on peptidomics and bioactivity

This study investigated and compared the differences in gastrointestinal digestion among fresh pork, Chinese sausage, and Chinese sausage inoculated with Staphylococcus (S.) carnosus RT6. The results indicated that fermentation treatment improves gastric digestibility by inducing protein denaturation, transforming β-sheets into random coils and β-turns. The sausages inoculated with S. carnosus exhibited the best protein digestion characteristics, with the highest combined gastric/intestinal digestibility (77.38%). During in vitro gastrointestinal digestion, sausage inoculated with S. carnosus RT6 released more peptides (517) than traditional Chinese sausages (304) and fresh pork (134). The S. carnosus RT6 inoculate also yielded a higher proportion of peptides with molecular weights <1000 Da (36.21%) and more unique peptides. Furthermore, the digested peptides from the S. carnosus RT6 treatment were more widely distributed across the 3D structure of actin than those from the other treatments. The digested products of sausage inoculated with S. carnosus RT6 demonstrated superior radical scavenging activity, with DPPH, hydroxyl (·OH), and ABTS radical scavenging rates reaching 71.3%, 83.2%, and 80.5% respectively, and enhanced overall antioxidant capabilities. This study highlights the potential application of S. carnosus RT6 as a starter culture to enhance the nutritional quality of fermented sausage.