Question

How does the addition of curd to a small amount of fresh milk help in the formation of curd? Mention a nutritional quality that gets added to the curd.

Answer 1

Hint: Curd is a dairy product made by coagulation of milk by a process called curdling. Small amount of curd that is added to milk contains millions of lactic acid bacteria and LAB plays a very important role in checking disease causing microbes.

Complete answer:
Microorganisms like Lactobacillus and others, often called lactic acid bacteria, grow in milk and turn it into cottage cheese. As they grow, LAB produces acid which thickens and partially digests milk protein. The starter, or inoculum, contains millions of LAB which will multiply at the right temperature, turning milk into curd.
Nutritional quality - Curd is more nutritious than milk as it contains a number of vitamins especially vitamin B12. In our stomach LAB plays a very beneficial role in disease causing microbes.

Additional Information:
Other fermented milk products:
Yogurt is made by fermenting whole milk using a mixed culture of Lactobacillus bulgaricus and Streptococcus thermophilus. L. bulgaricus produces acetaldehyde which gives it a distinctive taste, while S. thermophilus causes the formation of lactic acid which gives it a sour taste.
The popularity of acidophilus milk is primarily related to its health effects, which are believed to be related to the ability of Lactobacillus acidophilus to colonize the intestines. It is a thermophilic homo-fermenter, but it ferments slowly, is uncompetitive, and grows easily.
Kefir and koumiss are typical fermented milk products obtained by fermentation of mixed lactobacilli and fermented alcoholic yeast. Kefir is also distinguished by the fact that the excitatory microflora is unevenly distributed in milk, and is added in the form of a separate "grain" of kefir.

Note:
The process of making milk curd with the help of lactic acid bacteria is called curdling, while yogurt is formed by fermentation of lactobacilli bacteria. Yogurt can be diluted into buttermilk by adding water. Commonly Lactobacillus acidophilus is used for converting milk to curd.