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

The pH value of milk will decrease.

Explanation

Fresh milk has a pH 6, during curdling, the lactobacillus keeps growing and it breaks down the lactose (the natural sugar in milk) into lactic acid which acidifies the milk even further. Therefore, the pH of the milk will drop (decrease). As the more acidic the substance the lower the pH.