Explain the changes that milk undergoes when suitable starter/inoculum is added to it. How does the end product formed prove to be beneficial for human health?

Lactobacillus is involved in settling milk into curd. At first, some amount of curd is placed in a milk which is used as inoculum. The bacteria use the sugar lactose in the milk. Oxidation of lactose to lactic acid takes place. Milk proteins coagulate to form curd. Vitamin B₁₂ is increased by the bacteria. Hence it is beneficial for human health.