Physicochemical, volatiles, non-volatiles, and microbial dynamics in dried versus traditional fresh red pepper paste fermentation: A comparative study

Abstract

The utilization of dried red peppers (DRPs) in fermented red pepper paste creation serves as a solution to the season-dependent availability of fresh red peppers (FRPs). Nevertheless, the current understanding of the fermentation disparities between DRPs and FRPs is limited, posing challenges to DRPs application in red pepper paste manufacturing. This study conducted a side-by-side analysis of physicochemical indicators, volatiles and non-volatiles, and microbial composition within DRPs and FRPs during fermentation, deploying a comprehensive multi-omics technique. The study results signified that after two weeks of fermentation, pH levels were significantly heightened (p < 0.05) in FRPs than in DRPs, with total acid presenting an opposite trend. Concurrently, total flavonoid content and the a* value were considerably elevated in FRPs (p < 0.05) during the entire fermentation process. Furthermore, the drying process led to substantial changes (p < 0.05) in red pepper metabolites, with higher total volatiles and non-volatiles found in FRPs throughout fermentation. The PLS-DA modeling indicated that 20 volatiles and 37 non-volatiles were screened as differential metabolites between the two pastes, respectively. The microbial composition analysis showed a similar fungal population in both DRPs and FRPs during fermentation, but drying significantly altered the bacterial composition, resulting in Weissella and Ligilactobacillus becoming dominant post-fermentation, whereas Pantoea and Ligilactobacillus dominated in DRPs paste. This study enriches our understanding of the fermentation process using various raw materials and paves the way for the development of DRPs-based red pepper paste that can be produced year-round.