we can measure how acidic something is by measuring its pH the lower the pH the more acidic it is the pH of milk is often 6.7 the pH of yoghurt is 4.5 explain what causes this change in pH as milk is changed to yoghurt

The causes of changing the pH of milk into yogurt are that the lactose in the milk is converted into lactic acid, which leaves the pH.

Explanation:

When the pH drops below pH5. The micelles of the caseins, a hydrophobic protein, lose its territory structure due to the protonation of the amino acid residues.

So the production of the amino acids forms the basic structure and texture of the yogurt. To turn the milk into the yogurt the first process is to ferment the milk and turning the lactose sugar in the milk into the lactic acid, then the lactic acid converted into the yogurt.