Multiple choice

Milk tastes sour when kept in the open for sometime due to formation of

  1. carbonic acid

  2. citric acid

  3. lactic acid

  4. malic acid

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

When milk is left open, bacteria (especially Lactobacillus) ferment the lactose sugar into lactic acid through anaerobic respiration. The accumulation of lactic acid lowers the pH, giving milk its characteristic sour taste. Carbonic, citric, and malic acids are not produced in this process.