Effect of low temperature on the shaping of yeast-derived metabolite compositions during wine fermentation

Low-temperature fermentation is considered to enrich the aroma of wine. The metabolism of Saccharomyces cerevisiae responding to low temperatures is intricate and this complexity is further enhanced by various strains and culture media. However, the real effects of low-temperature fermentation on yeast metabolism are unclear. Aiming to clarify the yeast-derived metabolite formation in a low-temperature winemaking range, fermentations were performed at 10, 15, and 20 degrees C, using five wine yeast strains in two media respectively. Tolerance toward low temperatures and metabolite compositions (including basic chemical compositions and volatile aroma compounds) of wine yeasts were analyzed. Results showed that ethanol, ethyl acetate, and ethyl butanoate increased with the temperature decreasing, while acetic acid, phenylethanol, phenylethyl acetate, ethyl decanoate, and ethyl hexadecanoate decreased with decreasing temperature. The linear relationship between fermentation temperature and the formation of ethanol, acetic acid, and phenylethanol might be fundamentally due to the growth changes caused by temperature. The enhanced production of ethyl acetate and ethyl butyrate followed by decreasing temperature probably resulted from low-temperature-stimulated enzymes in metabolic pathways. These findings reveal a typical profile of yeast-derived metabolites at low-temperature fermentation and provide evidence to support the application of low-temperature winemaking in the wine industry.