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.