Question

Can you describe what happens when milk is converted to curd or yoghurt from your understanding of protein?

Answer 1

Hint: Curd is a dairy product obtained by calculating milk in a process called curdling. The yoghurt is formed by the bacterial fermentation of milk. In India Yoghurt is commonly called Dahi and Curd.

Complete answer:
Milk is converted into Dahi, curd, or Yoghurt by the process of fermentation. Milk consists of globular proteins called casein. The curd forms because of the chemical reaction between the lactic acid bacteria and casein. During fermentation, the bacteria use enzymes to produce energy (ATP) from lactose. The byproduct of ATP production is lactic acid. Lactic acids act on the globular proteins present in the milk and denature them. This denaturation destroys the tertiary and quaternary structures of proteins and the globular proteins are converted into fibrous proteins thus giving a thick texture to the milk due to coagulation of the proteins. In cow’s milk, 90% of the proteins are caseins. The preparation of curd required a lactobacillus bacteria, while yoghurt is made using two specific strains of bacteria called Lactobacillus Edelbrock subs Bulgaria and streptococcus thermophilus bacteria.
Using rennet to make curd attaches the lactose to the solid coagulated proteins. Thus it is not recommended for people with lactose intolerance. This curd is the commercial cheese available in markets such as Cheddar, Mozzarella, Parmesan.

Note: The chemical formula for curd is \[2 - \] hydroxy propanoic acid \[\left( {{C_3}{H_6}{O_3}} \right)\]
> Formation of new substance takes place hence curd is a chemical change.
> The curd forms because of the chemical reaction between the lactic acid bacteria and casein.
> The yogurt itself has a generally aldehydic flavor, which is a result of the fermentation process.