Screening ester-producing yeasts to fortify the brewing of rice-flavor Baijiu for enhanced aromas

Abstract

To enhance the aromas in Guangdong rice-flavor Baijiu, ester-producing yeast was selected to fortify Baijiu brewing. Among eight kinds of ester-producing yeasts selected, Saccharomyces cerevisiae CM15 (CM15) that showed both the stronger ability to utilize substrates to produce esters and the excellent tolerance to industrially relevant stress factors was chosen. When CM15 was synergistically fermented with six kinds of Kojis from distilleries of rice-flavor liquor in Guangdong, the enhanced total esters had happened to the liquors brewing with the fortified four kinds of Kojis, especially with Koji F. When Koji F was fortified with CM15, the resultant Baijiu showed a higher esters proportion and a lower higher alcohol ratio than that of Baijiu brewed only with Koji F, with the content of ethyl acetate and ethyl lactate increasing by 25% and 214%, respectively. This study suggested that CM15 can be used as a functional microorganism to fortify Baijiu brewing, which might also be suitable for other traditional fermented foods.

Strategies and Challenges of Microbiota Regulation in Baijiu Brewing

“…Biofortification of Baijiu microecology with functional strains can optimize the microbial community structure, flavor metabolism, and yield output of the fermentation system [ 71 , 86 ]. The effects of biofortification on Baijiu fermentation are many and varied.…”

“…In order to improve the yield and quality of Baijiu, high production of esters has been used as a requirement for the screening of target yeast strains. After obtaining the target strains, the researchers increased the content of esters such as ethyl hexanoate and ethyl acetate in Baijiu by making fortified Daqu or pure-strain suspensions [ 38 , 71 , 87 ]. It has also been shown that the addition of a single exogenous yeast strain also increases the levels of compounds such as ethanol, phenylethanol, and tetramethylpyrazine in the fermentation system [ 83 ].…”