Fermented vegetable flavors are closely associated with microbial metabolism. Here, shifts in flavor metabolites and their correlations to the structure and function of fermentative microbial communities were explored during the spontaneous fermentation process of potherb mustard ( Brassica juncea var. multiceps ), a traditionally fermented vegetable from China. Halophilic bacteria (HAB, i.e. , Halomonas , Salinivibrio , and Vibrio ) and lactic acid bacteria (LAB, i.e. , Lactobacillus -related genera and Weissella ) became highly abundant after potherb mustard fermentation. Further, HAB and LAB abundances exhibited significant, positive correlations with metabolites important in fermented potherb mustard flavoring (e.g., organic acids, amino acids, alcohols, aldehydes, and nitriles). Metagenomic analysis indicated that Halomonas , Salinivibrio , Weissella , and Lactobacillus -related genera were likely actively engaged in pyruvate metabolism (ko00620) and citrate cycle (TCA cycle, ko00020), leading to higher lactic and acetic acid concentrations, along with lower pH, which would affect levels of volatile isothiocyanates and nitriles that contribute to flavoring of fermented potherb mustard. Further, HAB and LAB were the primary populations inferred to be responsible for amino acid and fatty acid metabolism in addition to the biosynthesis of numerous volatile flavor compounds. This study highlights the predominance and importance of LAB and HAB during spontaneous fermentation of potherb mustard and provides new insights into their roles in this process.
Anaerobically fermented pickled tea (PT) can be produced by spontaneous fermentation (SF) or yeast-enhanced fermentation (YF). Aroma and taste characteristics of PT during YF and SF were investigated using sensory evaluation, odour activity, aroma character impact values, HS-SPME-GC–MS, UPLC-QQQ-MS/MS, and spectrophotometry, annotating 198 volatile and 115 non-volatile components. The main contributing volatile components were β-ionone, and 1-octanol, promoted by YF and SF, and yielding floral and fruity aromas respectively. Additionally, compared with SF, YF promoted the formation of citronellol yielding a floral aroma, inhibited the stale aroma of methoxybenzenes, and reduced bitter, astringent, and sour tastes. Furthermore, partial least-squares regression analysis identified the main components related to the ‘acides aroma’ of PT as linalool oxide, n -decanoic acid, hexanoic acid, 3,7-dimethyl-2,6-octadienoic acid, 3-methyl-1-dodecyn-3-ol, and nerolidol. This application could be used as methodology for the comprehensive analysis of tea aroma and taste and these results can act as guidelines for PT production and quality control.
危险品化学品经营许可证（带存储）