Effects of brown sugar addition and fermentation time on metabolites and microbial communities of Yibin Yacai

Abstract

Yibin Yacai is one of the most popular pickled vegetables in Sichuan made from special local stem mustard via spontaneous fermentation. The final quality of the Yibin Yacai product depends on every manufacturing process that affects the microbial communities during fermentation. In this study, the effects of brown sugar addition and fermentation time on physicochemical quality, flavor, and microbial communities of Yibin Yacai under five different fermentation conditions were investigated. The brown sugar addition can effectively increase the activities of microorganisms such as Lactobacillus and Debaryomyces, resulting in an increase in lactic acid content, sweet amino acids and umami amino acids. Furthermore, fermentation time plays a critical role in determining their physicochemical quality and flavor. The Yibin Yacai samples fermented for 5 years present the highest content of reducing sugar, amino acid nitrogen, esters, aldehydes, and olefins, while having the lowest salinity. These results indicate that the brown sugar addition and fermentation time could significantly influence the physicochemical and flavor qualities of the Yibin Yacai by tuning microbial communities during fermentation. These findings reveal the importance of controlling manufacturing processes for traditionally fermented Yibin Yacai and provide a new perspective on the technological innovation of fermented Yibin Yacai.