Role of Tween 80 and Monoolein in a Lipid-Sterol-Protein Complex Which Enhances Ethanol Tolerance of Sake Yeasts

An exogenous ternary complex composed of Tween 80, ergosterol, and albumin increased the final ethanol concentration of fermentation by sake yeasts from 17.2 to 19.0% (vol/vol) and reduced the fermentation time from 30 to 25 days. Likewise, a complex of monoolein, albumin, and either ergosterol or ergosteryl oleate increased the final ethanol concentration of fermentation to 19.7 or 19.8% (vol/vol), respectively, and reduced the fermentation time to 25 days. Both Tween 80 and monoolein promoted the fermentative activity (Q_CO2) of cells, and the effect was enhanced by the presence of ergosterol.