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Summary: The ethanol fermentation efficiency was affected by multiple stress tolerance of yeast during brewing and bioethanol industry. The effect of KCl on the multiple stress tolerance of yeast cells was examined. Results showed that KCl addition significantly enhanced the tolerance of yeast cells to osmotic and ethanol stress, which correlated with the decreased membrane permeability, the increased intracellular ergosterol and ATP content, and the improved activity of complex II and complex III in yeast cells. Biomass and viability of yeast cells under osmotic and ethanol stress were increased significantly by KCl addition. Supplementation of 4 and 10 g L−1 KCl exhibited the best promotion activity for yeast cells present in medium with 500 g L−1 sucrose and 10% (v v−1) ethanol, respectively. These results suggested that exogenous potassium addition might be an effective strategy to improve yeast tolerance and fermentation efficiency during industrial very‐high‐gravity (VHG) fermentation. [ABSTRACT FROM AUTHOR]

Wheat gluten hydrolysates (WGH) and KCl were used to examine their effects on fermentation performances and physiological characteristics of brewer's yeast during very high gravity (VHG) fermentation. Results showed that all supplementations exhibited a notable promotion in yeast growth, glucose utilization, ethanol production, and physiological characteristics. Combination supplementation of 0.3% WGH and 0.5% KCl showed the best promotion effect with 6.38%, 9.41% and 8.68% of increases in biomass, glucose utilization and ethanol production, respectively. Moreover, combination addition of WGH and KCl also enhanced significantly membrane integrity and mitochondrial functionality of brewer's yeast. Amino acid compositions of WGH and intracellular metabolites analysis indicated that active nitrogen metabolism and high levels of stress resistant substances might be responsible for the improvement of growth and fermentation performances in brewer's yeast by nutrient supplementation. • WGH and KCl supplementations promoted cell growth and fermentation of yeast. • WGH and KCl addition improved membrane integrity and mitochondrial functionality. • Combination of 0.3% WGH and 0.5% KCl showed the best bioactivity for yeast. • Active nitrogen metabolism and stress resistant substances were related to activity. [ABSTRACT FROM AUTHOR]