Characterisation of flavour profiles and microbial communities of fermented peppers with different fermentation years by combining flavouromics and metagenomics

The changes in flavours, volatile aromas and microbial communities of fermented peppers with different fermentation years and their relationships were investigated in this study. Results indicated a gradual increase in organic acids during fermentation, whereas free amino acids and capsaicinoids reached stability after 1 year of fermentation. Overall, the analysis detected 340 volatile compounds in fermented peppers and regarded 69 of them as differential compounds. Peppers fermented for 2 (FY2) and 4 years (FY4) possessed a greater number of differential volatiles with large odour activity values, thus endowing them with more favourable flavours. Hence, metagenomic analysis compared their microbial communities and functional annotations. Results revealed that Lactiplantibacillus plantarum and Zygosaccharomyces rouaii were the dominant bacterium and fungus, and metabolism was the main Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway in FY2. Correlation analysis demonstrated that Hyphopichia, Kazachstania and Clavispora were highly positively correlated with 12 key aroma flavours.