Question

While preparing curd, a little curd is added to warm milk. The reason behind this is:
a. Curd contains several microbes which promote the formation of curd.
b. Only lactobacillus present in curd promotes curd formation in milk.
c. Lactobacillus multiplies in milk and converts it into curd.

A) a,b
B) b,c
C) a,c
D) All of the above

Answer 1

Hint: Lactobacillus belongs to lactic acid bacteria group which means they convert sugars to lactic acid. It is prominently found in probiotic foods such as curd and yoghurt. It undergoes the process called fermentation.

Complete answer:
Lactobacillus is a gram-positive, rod-shaped and non-spore-forming bacteria, which belongs to the group of lactic acid bacteria that are used to convert sugars into lactic acid. They undergo the process of multiplication that converts milk into curd. The curd formation can be done by two methods. Firstly, some sort of acidic substances like lemon juice or vinegar is added to the milk. Another method includes preparing by addition of lactic acid bacteria inoculum from the previous curd stock to the raw or boiled milk. For making curd, leftover non-refrigerated milk can also be used. To the warm or unrefrigerated milk, little curd is added and it is left to coagulate. The process of coagulation of milk to form curd is known as curdling. The curd protein gets tangled into a solid mass called curd. During curd formation, whey is formed. It is the liquid part of the milk which is separated out and later drained off to retain the only card. The process that is involved in the formation of curd is known as fermentation. It occurs in the absence of oxygen.
Hence, the correct answer is option B.

Note: Lactobacillus is considered to be probiotic food which is good for human health. Such bacteria are responsible for maintaining gut health. It is mostly found in foods such as curd and yoghurt and it helps to treat conditions such as diarrhoea, vaginal infection and skin disorders such as eczema.