高浓发酵和酸洗对酿造酵母的影响

Effects of High-gravity Brewing and Acid Washing on Brewer's Yeast

用磷酸类杀菌物质来洗涤接种酵母， 以避免细菌污染是许多啤酒厂通用的方法， 使用不正确的方法洗涤酵母将使其发酵特性下降并产生不良影响。酵母酸洗后接种于１２‘Ｐ麦汁，发酵特性没有明显下降；而接种于２０‘Ｐ麦汁，在发酵的第一个２４ 小时，酵母的活力就有所下降，但酵母的发酵特性没有变化。通过检测２０‘Ｐ麦汁的糖，发现葡萄糖的利用率下降，导致麦芽糖的利用滞后，在１２‘Ｐ麦汁中，葡萄糖和麦芽糖的利用没有这种现象。

Washing pitching yeast with bactericidal substances such as phosphic acid to eliminate bacterial contamination is common practice in many breweries.Washing pitching yeast incorectly will adversely effect the yeast and result in decreasing the ferrmentation peformance.When yeast was washed with acid and repitched into 12P wort,no decrease in fermentation performance was observed but after repitching in 20P wort,a small decrease in viability was observed over the first 24 hr of the fermentation.The fermentation profile of yeast serially repitched in 20P wort matched that of the control yeast.On examination of the wort sugars, a decreased rate at which glucose was removed from the wort was observed,which resulted in a log phase before maltose could be utilized from 20P wort.No adverse effect on glucose and maltose utilization from 12P wort noted.