Ester‐synthesis mechanism and activity by Bacillus licheniformis, Candida etchellsii and Zygosaccharomyces rouxii isolated from Chinese horse bean‐chili‐paste

BACKGROUND Esters are indispensable aroma compounds and contribute significantly to fruity-aroma in fermented condiments. The ester-synthesis activity and pathway of Bacillus licheniformis, Candida etchellsii and Zygosaccharomyces rouxii isolated from Chinese horse bean-chili-paste were investigated. Chemical buffer models containing esterification and alcoholysis systems inoculated with extracellular extracts of these three strains were established. RESULTS The ester-synthesis activity of C. etchellsii was stronger than the other two strains. Z. rouxii could synthesize acetate esters via esterification, while the biosynthesis pathways of B. licheniformis and C. etchellsii were esterification and alcoholysis. Esterification exhibited relatively high activity at pH 4, while the alcoholysis activity improved with the increase of pH from 4 to 8. Moreover, C. etchellsii could synthesize C6 -C8 of acetate esters, and its activity improved with the number of alcohol carbon atoms. These three strains could synthesize C10 -C18 of ethyl esters. Their synthesis activity of ethyl esters decreased with aliphatic acid carbon number. CONCLUSION Candida etchellsii is potential to be used in CHCP fermentation in order to the accumulation of esters and the improvement of flavor compared with the other two strains. This research is conducive to understanding the mechanism of ester-synthesis in fermented condiments. This article is protected by copyright. All rights reserved.