Lei Hongjie, Xu Huaide, Feng Li, Yu Zhimin, Zhao Haifeng, Zhao Mouming
College of Food Science and Engineering, Northwest A&F University, No. 22 Xinong Road, Yangling 712100, China.
School of Biological Engineering, Dalian Polytechnic University, No. 1 Qinggongyuan Road, Dalian 116034, China.
J Biosci Bioeng. 2016 Nov;122(5):583-588. doi: 10.1016/j.jbiosc.2016.05.004. Epub 2016 Jun 18.
The effects of glucose, sucrose and maltose supplementations on the fermentation performance and stress tolerance of lager yeast (Saccharomyces pastorianus) during high gravity (18°P) and very high gravity (24°P) fermentations were studied. Results showed that throughout 18°P wort fermentation, fermentation performance of lager yeast was significantly improved by glucose or sucrose supplementation, compared with maltose supplementation, especially for sucrose supplementation increasing wort fermentability and ethanol production by 6% and 8%, respectively. However, in the later stage of 24°P wort fermentation, fermentation performance of lager yeast was dramatically improved by maltose supplementation, which increased wort fermentability and ethanol production by 14% and 10%, respectively, compared with sucrose supplementation. Furthermore, higher HSP12 expression level and more intracellular trehalose accumulation in yeast cells were observed by maltose supplementation with increase of the wort gravity from 18°P to 24°P, indicating higher stress response of yeast cells. The excretion of Gly and Ala, and the absorption of Pro in the later stage of fermentation were promoted by maltose supplementation. In addition, with increase of the wort gravity from 18°P to 24°P, higher alcohols level was decreased with maltose supplementation, while esters formation was increased significantly with glucose supplementation. This study suggested that the choice of optimal fermentable sugars maintaining better fermentation performance of lager yeast should be based on not only strain specificity, but also wort gravity.
研究了葡萄糖、蔗糖和麦芽糖添加物对贮藏酵母（巴氏酵母）在高浓度（18°P）和超高浓度（24°P）发酵过程中发酵性能和耐胁迫能力的影响。结果表明，在18°P麦芽汁发酵过程中，与添加麦芽糖相比，添加葡萄糖或蔗糖可显著提高贮藏酵母的发酵性能，尤其是添加蔗糖可使麦芽汁发酵度和乙醇产量分别提高6%和8%。然而，在24°P麦芽汁发酵后期，添加麦芽糖可显著提高贮藏酵母的发酵性能，与添加蔗糖相比，麦芽汁发酵度和乙醇产量分别提高了14%和10%。此外，随着麦芽汁浓度从18°P提高到24°P，添加麦芽糖可使酵母细胞中HSP12表达水平更高，细胞内海藻糖积累更多，表明酵母细胞的应激反应更高。添加麦芽糖可促进发酵后期甘氨酸和丙氨酸的排泄以及脯氨酸的吸收。此外，随着麦芽汁浓度从18°P提高到24°P，添加麦芽糖可降低高级醇含量，而添加葡萄糖可显著增加酯类的形成。本研究表明，选择能保持贮藏酵母更好发酵性能的最佳可发酵糖不仅应基于菌株特异性，还应基于麦芽汁浓度。
