The convertion of milk to curd improves its nutritional quality by increasing which one of the following vitamin ?

Vitamin B₁₂

The conversion of milk to curd does not significantly affect the levels of vitamin C, vitamin D, or vitamin K. However, it can increase the levels of vitamin B₁₂ in curd. Vitamin B₁₂ is produced by certain bacteria present in the curd culture during the fermentation process.

During the fermentation of milk to make curd, lactic acid bacteria, such as Lactobacillus spp. and Streptococcus spp., convert lactose (the sugar present in milk) into lactic acid. These bacteria also have the ability to synthesize vitamin B₁₂. Therefore, when milk is converted to curd, the vitamin B₁₂ content may increase due to the metabolic activity of these bacteria.

It's important to note that the increase in vitamin B₁₂ content in curd during fermentation may vary depending on factors such as the specific curd culture used and the fermentation conditions.