Aroma-oriented starter culture selection reveals strain-dependent flavor formation in fermented chili peppers.

Yeasts play a crucial role in aroma formation during chili pepper fermentation, but strain-dependent insights into yeast-driven flavor formation remain limited. In this study, aroma-producing yeasts were isolated from aged fermented chili peppers and screened using an aroma-oriented strategy. Five representative yeasts were selected and characterized for phenotypic and metabolic traits, esterase activity, and safety. During fermentation, yeast inoculation had limited effects on acidification but significantly influenced sugar utilization, capsaicinoid transformation, taste attributes, and volatile aroma profile. GC-MS analysis identified 108 volatile compounds, and yeast inoculation promoted esters, alcohols, and terpenoid-related compounds in a strain-dependent manner. Notably, Starmerella lactis-condensi and Zygosaccharomyces rouxii were associated with higher ester and alcohol levels. Odor activity value analysis revealed 12 key aroma-active compounds, including ethyl esters, β-ionone, and isoamyl alcohol, contributing to overall aroma. These findings elucidate strain-dependent roles of yeasts in fermented chili peppers and provide a scientific basis for developing aroma-oriented starter cultures.