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

(N/A) The $pH$ of fresh milk is $6$. As milk turns into curd,the process involves the fermentation of lactose sugar into lactic acid by bacteria such as $Lactobacillus$. Since lactic acid is acidic in nature,the concentration of hydrogen ions $(H^+)$ increases in the solution. Consequently,the $pH$ value will decrease to below $6$ as the milk becomes more acidic.