The Intraspecies Heterogeneity of Wild Staphylococcus Equorum in Starter Cultures Drives Differences in Physicochemical and Aroma Characteristics in Chinese Fermented Sausage

This study aimed to investigate the impact of intraspecific heterogeneity of Staphylococcus equorum on the physicochemical and aroma characteristics of Chinese fermented sausage. S. equorum strains E-1, NY-3, EH-4, and EH-6 were selected for their environmental resilience, flavor-enhancing potential, and safety, and each was co-inoculated with Pediococcus pentosaceus TP-1 and Staphylococcus xylosus TS-1 to prepare Chinese fermented sausage. The results demonstrated that, compared with the uninoculated fermented sausages, inoculation with starter cultures significantly decreased the pH, moisture content, and water activity ( a w ) of the sausages ( P < 0.05). In particular, the pH declined by approximately 0.14–0.23 units on average, the moisture content decreased by about 0.09–2.5%, and the a w was reduced by 0.004–0.035. Sausage inoculated with S. equorum NY-3, P. pentosaceus TP-1, and S. xylosus TS-1 (TNY-3) exhibited the highest fruity, cheesy, and sweet scores, attributed to elevated levels of ethyl esters and aldehydes. TE-1, inoculated with S. equorum E-1, P. pentosaceus TP-1, and S. xylosus TS-1, showed an increased concentration of ethyl ester compounds. Meanwhile, TEH-4 and TEH-6 exhibited higher levels of methyl esters, which have relatively high odor detection thresholds.