碱性和支链氨基酸对啤酒高浓酿造酵母发酵性能的影响

研究分别考察添加三种碱性氨基酸：精氨酸（Arg）、赖氨酸（Lys）、组氨酸（His）与支链氨基酸：缬氨酸（Val）、亮氨酸（Leu）、异亮氨酸（Ile）对24 °P高浓酿造过程中酵母发酵性能及啤酒风味的影响。结果表明，六种氨基酸的添加可促进酵母生长并提高活细胞率，显著提高麦汁发酵度及乙醇产量。其中，添加Val、Leu与Arg的高浓麦汁发酵性能较好，与对照组相比，发酵结束时总CO2失质量分别为92.4 g/L、92.7 g/L与91.2 g/L；发酵度极显著提高（P＜0.01），分别为83.65%、82.95%和82.93%；乙醇产量极显著提高（P＜0.01），分别为11.97%（V/V）、11.90%（V/V）和11.83%（V/V）。添加Arg可显著提高酵母总细胞数（1.64×108 cells/mL）（P＜0.05），His、Val与Leu的添加对风味物质影响较大，可提高啤酒的醇酯比，其中，Val的添加可显著提高异丁醇含量（P＜0.05），降低总酯含量；Leu的添加则可同时提高异戊醇及乙酸异戊酯的含量。

Effect of alkaline and branched chain amino acids on fermentation performance of yeast during beer high gravity brewing

The effects of three alkaline amino acids (Arg, Lys, His) and three branched chain amino acids (Val, Leu, Ile) supplementations on yeast fermentation performance and flavor formation during beer high gravity brewing (24 °P) were studied. The results showed that six amino acids supplementations could promote yeast cell growth, increase yeast cell viability, and significantly increase wort fermentation degree and ethanol yield. Compared with control, Val, Leu and Arg supplementations showed better fermentation performance. At the end of fermentation, the total CO2 loss was 92.4 g/L, 92.7 g/L and 91.2 g/L, respectively, and the fermentation degree and ethanol yield were highly significantly improved (P＜0.01), which were 83.65% and 11.97% (V/V), 82.95% and 11.90% (V/V), 82.93% and 11.83% (V/V), respectively. Arg supplementation resulted in a significant increase in the total number of yeast cells (1.64×108 cells/ml) (P＜0.05). His, Val and Leu supplementations showed a great influence on the flavor substances, and increased the ratio of alcohols to esters. Among them, Val supplementation significantly increased the content of isobutanol and reduced the content of total ester (P＜0.05), while Leu supplementation increased the content of isoamyl alcohol and isoamyl acetate.