变酸

Milk clots when it turns sour.

变酸就凝块。

If you leave milk in the sun, it goes sour quickly.

如果放在阳光下，它会很快变酸。

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.

啤酒中污染的常见菌有细菌、霉菌、野生酵母菌,但主要存在害较大的菌是细菌中的大部分厌氧菌,会使啤酒产生浑浊、变味、变酸等。