Relationship between microbial community and flavor profile during the fermentation of chopped red chili (Capsicum annuum L.)

To reveal the potential relationship between microbial community and flavor compounds during the fermentation of chopped red chili, microbial diversity and volatile metabolites at different stages were analyzed by high-throughput sequencing and gas chromatography-mass spectrometry. The results showed that Pseudomonas was the most dominant bacterial genus in fermented chopped red chili (FCRC), while unclassified_f__Nectriaceae and Colletotrichum were the most abundant fungal genus initially but were quickly replaced by Wickerhamomyces and Hyphopichia. Besides, citric acid and acetic acid were the most abundant organic acids, and esters were the dominant volatile flavor compounds in FCRC. Notably, the formation of flavor compounds in FCRC can be divided into three stages: the first stage is day 0, the second stage is day 3–10, and the third stage is day 15–20. Based on the O2PLS model, 13 bacterial genera highly correlated (|ρ| > 0.7) with flavor compounds and Exiguobacterium was correlated with 26 flavor components, having the largest numbers of correlated flavor compounds, while only four fungal genera correlated with flavor compounds (|ρ| > 0.7) and unclassified_f__Nectriaceae was correlated with 11 flavor components. Moreover, the correlation analysis suggested that Exiguobacterium and Aureimonas were the core bacteria to produce the key flavors of FCRC, while unclassified_f__Nectriaceae, Wickerhamomyces and Hyphopichia were the core fungus. These findings provide novel insights into the variation of bacterial and fungal communities and increase our understanding of the core aroma-related microbiota involved in manufacturing FCRC with distinctive flavor properties.