Question

Lactic acid bacteria grow in milk and convert it into curd increasing its nutritional value by increasing
A. Vitamin A
B. Vitamin $B_6$
C. Vitamin $B_{12}$
D. Both A and C

Answer 1

Hint: Lactic acid bacteria or Lactobacillus produce lactic acid as a metabolic byproduct of carbohydrate fermentation. This has various other uses.

Complete answer:
Option A: Vitamin A is fat-soluble retinoids. Carrots, animal liver, etc are some excellent sources of vitamin A. Deficiency of vitamin A will cause night blindness. Dairy products also contain vitamin A, but not in a rich amount. Therefore, this is the incorrect option.

Option B: Vitamin B6 is water-soluble vitamins obtained through a variety of food items such as poultry, soybean, etc. They help in gluconeogenesis and facilitate many enzymatic reactions. Deficiency of vitamin $B_6$ will result in anemia, skin rashes, and a weakened immune system. Dairy products are not a major source of vitamin $B_6$. Therefore, this is the incorrect option.

Option C: Vitamin $B_{12}$ is a very essential nutrient. It helps in the synthesis of DNA. Vitamin $B_{12}$ also helps red blood cells synthesis and through this it prevents anemia. Some strains of Lactic acid bacteria are capable of synthesizing water-soluble vitamin $B_{12}. The fermentation of milk with the help of Lactic acid bacteria will enrich vitamin $B_{12}$ in it. Therefore the curd will have a high bioavailability of vitamin $B_{12}$ . Therefore this is the correct answer.
The other vitamin abundant in curd is vitamin $B_2$.

Option D: Since curd is not a major source of vitamin A, option A is wrong. Therefore, this is the incorrect option.

Hence, the correct answer is option (C)

Note: 1)The use of lactic acid bacteria with the help of biotechnology can facilitate vitamin enrichment in desired products.
2)Also the byproducts of fermentation can be used to make alcohols.