The usaul contaminate in beer are bacterium,fungus and wild yeast, most of them are anaerobion causing the muddy, flavor chaging and turning sour, Beer anaerobic culture medium should be found out.

啤中污染的常见有细、霉、野生酵母,但要存在危害性较大的是细中的大部分,会使啤产生浑浊、变味、变酸等。