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(b) Fresh milk has a pH of 6. How does the pH will change as it turns to curd? Explain your answer.
Answers
The pH of fresh milk is 6. As milk turns into curd, lactic acid is formed due to which it become more acidic. Therefore, the pH of milk will reduce.
As the milk turns into curd, its pH will fall below 6 (it will become more acidic). This is because an acid (lactic acid) is produced when milk turns into curd.
Explanation:
The pH of milk is 6 while that of curd is of the range 4.5 - 5.5. The pH decreases as milk changes into curd. This is because of the formation of lactic acid which as the name suggests is acidic in nature. When it changes to curd its pH will decrease.When the milk is converted into curd due to the action of bacteria, lactic acid is formed which is more acidic in nature. Therefore the pH value of the milk is reduced as it turns to curd.Yogurt is a product of the acidic fermentation of milk. The lactose in the milk is converted to lactic acid, which lowers the pH. When pH drops below pH 5, micelles of caseins, a hydrophobic protein, loses its tertiary structure due to the protonation of its amino acid residues.