Screening of aroma-producing Saccharomyces cerevisiae strains and their effects on the flavor profiles of mechanized Huangjiu

Mechanized Huangjiu (Chinese rice wine) is characterized by a stable flavor quality and short fermentation time, yet its flavor quality is inferior to that of traditional Huangjiu. Given the significant market demand for high-quality mechanized Huangjiu and the existing flavor quality gap, this study aimed to isolate and identify highly efficient aroma-producing yeasts from the fermentation mash of traditional Huangjiu for application in mechanized Huangjiu production. From 26 isolated strains, three Saccharomyces cerevisiae strains (OS7302, q1, and NL9) were selected based on their high aroma production capacity in simulated fermentation media. Gas chromatography-mass spectrometry (GC–MS), gas chromatography-olfactometry (GC–O), sensory evaluation, and physicochemical analysis were then combined to systematically verify their abilities to produce aroma compounds. In co-fermentation with mechanized starter cultures, S. cerevisiae OS7302 induced significant increases in the concentrations and aroma intensities of key esters, including ethyl hexanoate, ethyl caprate, and ethyl caprylate, thereby generating an ester aroma profile of mechanized Huangjiu comparable to that of traditional Huangjiu. Furthermore, Huangjiu fermented with S. cerevisiae OS7302 exhibited more intense fruit and ester aromas. In contrast, strains q1 and NL9 promoted the formation of higher alcohols. The use of aroma-producing S. cerevisiae as adjunct cultures for co-fermentation with mechanized starter cultures can improve the flavor quality of mechanized Huangjiu, alleviating the flavor gap between mechanized and traditional Huangjiu.