This year marks the 200th anniversary of the birth of Dr. Louis Pasteur (1822–1895), who revealed that alcoholic fermentation is performed by yeast cells. Subsequently, details of the mechanisms of alcoholic fermentation and glycolysis in yeast cells have been elucidated. However, the mechanisms underlying the high tolerance and adaptability of yeast cells to ethanol are not yet fully understood. This review presents the response and adaptability of yeast cells to ethanol-induced protein denaturation. Herein, we describe the adverse effects of severe ethanol stress on intracellular proteins and the responses of yeast cells. Furthermore, recent findings on the acquired resistance of wine yeast cells to severe ethanol stress that causes protein denaturation are discussed, not only under laboratory conditions, but also during the fermentation process at 15°C to mimic the vinification process of white wine.

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Winemaking is a dynamic and complex process in which ethanol concentrations gradually increase to reach >10% (vol/vol) through alcoholic fermentation. However, there is little information on protein damage in wine yeast during winemaking.

Since yeast research under laboratory conditions is usually conducted at 25–30°C (moderate temperature range), most of the findings on yeast physiology are based on analyses in this temperature range. Due to inefficiencies in cultivation and analysis, insufficient information is available on yeast physiology in the low‐temperature range, although alcoholic beverage production is often conducted at relatively low temperatures (around 15°C). Recently, we reported that severe ethanol stress (10% v/v) inhibits proteasomal proteolysis in yeast cells under laboratory conditions at 28°C. In this study, proteasomal proteolysis at a low temperature (15°C) was evaluated using cycloheximide chase analysis of a short‐lived protein (Gic2‐3HA), an auxin‐inducible degron system (Paf1‐AID*‐6FLAG), and Spe1‐3HA, which is degraded ubiquitin‐independently by the proteasome. At 15°C, proteasomal proteolysis was not inhibited under severe ethanol stress, and sufficient proteasomal activity was maintained. These results provide novel insights into the effects of low temperature and ethanol on yeast physiology.