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.

啤酒中污染的常见有细、霉、酵母,但要存在危大的是细中的大部分厌氧,会使啤酒产浑浊、变味、变酸等。