A. lactic acid
B. citric acid
C. acetic acid
D. carbonic acid
¨ Milk tastes sour when kept in the open for some time due to the formation of lactic acid.
¨ This is because the lactose (a type of sugar) present in milk is converted into lactic acid by the action of bacteria, specifically Lactobacillus spp. and Streptococcus spp. These bacteria consume lactose as a source of energy and produce lactic acid as a byproduct. As the concentration of lactic acid increases, the pH of the milk decreases, making it more acidic and causing it to taste sour.
Submitted by :- Jamil Ahmed