Yunnan traditional rose jam is made from fresh Rosa ‘Crimson Glory’ petals and brown sugar through natural fermentation and has been consumed by local people for years due to its characteristic floral aroma. The present study investigated the dynamics and correlations between the microbial communities and flavor quality during 98-day fermentation at ambient temperature (23.72 ± 1.26 °C). The total titratable acidity (0.20–0.29 g/100 g) and reducing sugars content (0.92–5.37 g/100 g) increased with fermentation, while the pH (4.30–5.47), total phenolics content (0.25–0.72 g/100 g), and total flavonoids content (0.13–0.32 g/100 g) decreased. High-throughput 16S rDNA and ITS sequencing revealed that Klebsiella, Zygosaccharomyces, Starmerella, and Podosphaera were the dominant microorganisms. Esters and terpenoids were the main flavor substances. Based on relative odor activity value evaluation, the relative levels of volatile compounds responsible for rose, sweet, and fruity odors increased during fermentation, while those responsible for a green character diminished. The physicochemical properties, especially the total titratable acidity and reducing sugars, as well as esters and terpenoids were positively related with Zygosaccharomyces. The present study systematically elucidated the correlation between microbial communities and flavor formation during fermentation of Yunnan traditional rose jam, providing key scientific basis for flavor-targeted regulation and standardized production of this traditional fermented food.
Zhou et al. (Mon,) studied this question.