Multiple choice

When milk turns sour, one of the products formed is

  1. tartaric acid

  2. lactic acid

  3. citric acid

  4. ascorbic acid

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When milk turns sour, bacteria (mainly Lactobacillus) ferment lactose (milk sugar) into lactic acid through the process of fermentation. This is what gives sour milk its characteristic tangy taste and is the principle behind yogurt production.