Optimizing Baijiu fermentation with high-yield ethyl caproate-producing Candida parapsilosis strain

Ethyl caproate is an important flavor substance of Baijiu. It is effective to increase the content of ethyl caproate to improve the quality of strong-flavor Baijiu. In this study, the high-yielding ethyl caproate Candida parapsilosis strain F-5 was isolated from pit mud. Under optimized fermentation conditions, F-5 achieved an ethyl caproate yield of 53.69 mg/L. A novel strategy was employed by adding caproic acid and F-5 directly to the fermented grain. The application of F-5 in the fermentation of Xiaoqu and strong-flavor Baijiu significantly increased the ethyl caproate content by 24.86% and 17.45%, respectively. Transcriptomic analysis showed that Lip2 and esterase genes in the lipase synthesis pathway, and Fas1 , Fas2 , Eht1 , and Faa4 genes in the acyltransferase pathway were significantly upregulated. These findings suggest that strain F-5 has the potential to contribute to the development of artificial pit mud and improve the flavor quality of strong-flavor Baijiu.