Question

Fresh milk has a pH of $6$. How do you think the pH will change as it turns into curd?

• A. pH will reduce
• B. pH will increase
• C. It becomes same as milk
• D. None of the above

Answer 1

The correct option is A

pH will reduce

The correct option is option A

The explanation for the correct option:

1. Fresh milk has an acidic character due to its pH of $6$.
2. By the action of bacteria, this milk is transformed into curd, which further increases the curd's acidity and lowers its pH from 6 to less than 6.
3. The lactose in milk is converted to lactic acid which is present in curd.
4. A type of organic acid is lactic acid. Lactic acid is water soluble. When it is solid, it has a white appearance, but when it is liquid, it loses its color.
5. Lactic acid is also referred to as milk acid and it has a pH level of $3.51$.
6. Hence, the curd is more acidic than fresh milk.

Explanation of incorrect options:

Option (B): pH will increase

1. pH gets increased for a basic solution.
2. Whereas curd is acidic.
3. Hence, it is an incorrect option.

Option (C): it becomes the same as milk

1. Curd is more acidic than fresh milk, so the pH will get decreased.
2. Hence, it is an incorrect option.

Therefore, the pH will reduce when milk is converted into curd.