Improvement of quality and flavor profiles: Interaction effects of native Staphylococcus simulans and Staphylococcus equorum in Chinese-style fermented sausages

This study aimed to evaluate the improvement effects of native Staphylococcus simulans HZ01 and S. equorum SL05 on the physicochemical features, microbial parameters, volatile organic compounds (VOCs) and microbial diversity of the fermented sausages. The results demonstrated that individual inoculation of the two strains, as well as combined inoculation, significantly improved the color and inhibited lipid and protein oxidation of the fermented sausages. There were no significant differences among the three inoculating groups. The combined inoculation group significantly increased the nitrite content, compared with the individual inoculated groups. Quantitative PCR (qPCR) analysis results showed that inoculation groups significantly increased the amount of total Staphylococcus , while having no effect on the amount of total bacteria. A total of 46 VOCs were identified in the fermented sausages, and the inoculation groups significantly increased the combined proportions of aldehydes and alcohols to more than 53%, compared with 45% in the control group. Inoculation groups significantly increased the relative abundance of Staphylococcus to more than 6.90%, compared with that of the control (0.22%). In addition, inoculation of S. equorum in fermented sausages significantly reduced the relative abundance of Brochothrix thermosphacta and all six lactic acid bacteria species, while S. simulans had no corresponding effects. Pearson correlation analysis indicated S. simulans and S. equorum had obvious differences in flavor formation. This study provided a theoretical basis for the scientific use of coagulase-negative staphylococci alone or in combination.