What causes milk to curdle?

1 Answer
Aug 7, 2016

Milk curdles due to microbial activity.

Explanation:

Milk is composed of fats, proteins and sugars. Caesin ( milk protein)
is normally suspended in a colloidal form.
In warm and favourable temperatures Lactic acid Bacterium present in milk uses enzymes to produce energy ( ATP ) . The by - product of ATP production is lactic acid.
Increased acidity or decrease in pH causes caesin to tangle into solid masses of "curdles". The remaining liquid which contains only whey proteins is called whey.
Artificial curdling of milk can be achieved by adding rennet, lime juice or vinegar.