Question

Process of ……….. of milk proteins occurs due to lactic acid.
A. Gluconic acid
B. Coagulation
C. Amino acid
D. Acetic acid

Answer 1

Hint: Lactic acid is also called milk acid. When lactose undergoes fermentation, then the lactic acid is produced. It is an organic acid with formula $C_3H_6O_3$. It is found in sour milk, yogurt, etc.
In 1780, Carl Wilhelm Scheele (Swedish chemist) isolated lactic acid from the sour milk. Calcium lactate is used as the source of calcium and it is the soluble salt of lactic acid.

Complete answer:
Milk is a natural food that is present in liquid and is very necessary for the growth because it contains calcium and proteins (casein and whey). The protein is present due to the structures (primary, secondary and tertiary).
Now, according to the question we have to look upon options one by one.
Gluconic acid – It adds the flavor or acts as a flavoring agent in various food items – wine, dairy products, meat, etc.
Coagulation – It helps to separate the protein part from the non-protein part and the process called coagulation. In the presence of Lactobacillus the conversion of milk into curd occurs. This causes the coagulation and partial milk protein digestion.
Amino acids – There are 9 essential amino acids that are present in milk. But amino acid is not a process that causes milk protein.
Acetic acid – The acetic acid increases, then the yield of casein also increases. It is used to make the milk acidic in nature.

So, the correct answer is option (B) coagulation.

Note –
Lactobacillus is a gram-negative and anaerobic-bacteria. It is present in the form of a rod and is a non-spore forming bacteria. The dairy products that are produced in the presence of Lactobacillus we can easily consume due to their friendly nature.
Many other friendly bacteria are found in our guts other than Lactobacillus. The friendly bacteria, is also called as probiotics and they are responsible for digestion without harming the stomach.