酵母自溶的成因及其对啤酒质量的影响

酵母自溶由酵母胞内蛋白分解酶外泄引起，影响酵母自溶的因素有：(1)酵母菌种；(2)麦汁营养成分组成不合理；(3)酵母使用代数过高；(4)酵母添加量过多；(5)温度、压力、pH值等发酵工艺条件控制不当；(6)酵母回收时间、方法、压力、酵母贮存条件；(7)微生物污染。酵母自溶会影响啤酒风味稳定性，使啤酒苦味、涩味加重；啤酒双乙酰含量增加；啤酒的泡持性下降；啤酒总酸偏高；啤酒pH值升高；增加啤酒过滤成本。防止酵母自溶的方法有：(1)选择优良强壮的出发菌株；(2)控制酵母添加量和使用代数；(3)制备营养丰富、组成合理的麦汁；(4)严格发酵工艺奈件；(5)加强酵母质量管理；(6)加强卫生管理，保证纯种发酵。

Causations of Yeast Autolysis and Its Effects on Beer Quality

The release of intracellular album clastic enzyme resulted in yeast autolysis and the causations of yeast autolysis covered:1.yeast species;2.irrational composition of nutritional components in wort;3.application of yeast of higher generation;4.excessive ad-dition of yeast;5.inadequate control of fermentation techniques including temperature,pressure and pH value etc.;6.the recovery time ,method,pressure,and storage conditions of yeast;7.contamination with wild microbes.The yeast autolysis would influence the stability of beer flavor,result in bitterness and acerbity of beer,increase the diacetyl content in beer,reduce the durability of beer foam,cause higher total acid content and pH value in beer,and raise beer filtration cost.The methods to prevent yeast autolysis cov-ered:1.selection of superior primary microbial strains;2.adequate control of yeast addition quantity and yeast generation;3.prepa-ration of the wort with abundant nutrition and rational composition;4.operation of fermentation techniques strictly;5.strengthening the management of yeast quality;6.intensification of sanitary management to ensure fermentation of pure species.(Tran.by YUE Yang)