Casey G P, Ingledew W M
Crit Rev Microbiol. 1986;13(3):219-80. doi: 10.3109/10408418609108739.
It is now certain that the inherent ethanol tolerance of the Saccharomyces strain used is not the prime factor regulating the level of ethanol that can be produced in a high sugar brewing, wine, sake, or distillery fermentation. In fact, in terms of the maximum concentration that these yeasts can produce under batch (16 to 17% [v/v]) or fed-batch conditions, there is clearly no difference in ethanol tolerance. This is not to say, however, that under defined conditions there is no difference in ethanol tolerance among different Saccharomyces yeasts. This property, although a genetic determinant, is clearly influenced by many factors (carbohydrate level, wort nutrition, temperature, osmotic pressure/water activity, and substrate concentration), and each yeast strain reacts to each factor differently. This will indeed lead to differences in measured tolerance. Thus, it is extremely important that each of these be taken into consideration when determining "tolerance" for a particular set of fermentation conditions. The manner in which each alcohol-related industry has evolved is now known to have played a major role in determining traditional thinking on ethanol tolerance in Saccharomyces yeasts. It is interesting to speculate on how different our thinking on ethanol tolerance would be today if sake fermentations had not evolved with successive mashing and simultaneous saccharification and fermentation of rice carbohydrate, if distillers' worts were clarified prior to fermentation but brewers' wort were not, and if grape skins with their associated unsaturated lipids had not been an integral part of red wine musts. The time is now ripe for ethanol-related industries to take advantage of these findings to improve the economies of production. In the authors' opinion, breweries could produce higher alcohol beers if oxygenation (leading to unsaturated lipids) and "usable" nitrogen source levels were increased in high gravity worts. White wine fermentations could also, if desired, match the higher ethanol levels in red wines if oxygenation (to provide the unsaturated lipids deleted in part by the removal of the grape skins) were practiced and if care were given to assimilable nitrogen concentrations. This would hold true even at 10 to 14 degrees C, and the more rapid fermentations would maximize utilization of winery tankage.(ABSTRACT TRUNCATED AT 400 WORDS)
现在可以确定的是，所用酿酒酵母菌株固有的乙醇耐受性并非调节高糖酿造、葡萄酒、清酒或蒸馏酒发酵中所能产生的乙醇水平的主要因素。事实上，就这些酵母在分批发酵（16%至17%[v/v]）或补料分批发酵条件下所能产生的最大浓度而言，乙醇耐受性显然没有差异。然而，这并不是说在特定条件下，不同的酿酒酵母之间在乙醇耐受性方面没有差异。这种特性虽然是由基因决定的，但显然受到许多因素（碳水化合物水平、麦芽汁营养、温度、渗透压/水分活度和底物浓度）的影响，而且每个酵母菌株对每个因素的反应都不同。这确实会导致所测耐受性的差异。因此，在确定特定发酵条件下的“耐受性”时，考虑这些因素中的每一个都极为重要。现在已知每个与酒精相关的行业的发展方式在决定对酿酒酵母乙醇耐受性的传统看法方面发挥了重要作用。有趣的是，可以推测如果清酒发酵没有随着大米碳水化合物的连续糖化和同时糖化发酵而发展，如果蒸馏麦芽汁在发酵前进行澄清而啤酒麦芽汁不进行澄清，如果带有相关不饱和脂质的葡萄皮不是红葡萄酒原汁的一个组成部分，那么我们今天对乙醇耐受性的看法会有多大不同。与乙醇相关的行业利用这些发现来提高生产经济性的时机现在已经成熟。在作者看来，如果在高浓度麦芽汁中增加氧化（导致不饱和脂质）和“可用”氮源水平，啤酒厂可以生产出酒精度更高的啤酒。如果进行氧化（以提供因去除葡萄皮而部分缺失的不饱和脂质）并注意可同化氮的浓度，白葡萄酒发酵也可以根据需要达到与红葡萄酒中更高的乙醇水平相匹配。即使在10至14摄氏度的温度下也是如此，而且更快的发酵将使酿酒厂罐体的利用率最大化。（摘要截选至400字）
