Question

Which one is not used in the production of yogurt?
(A) Streptococcus lactic
(B) Streptococcus thermophilus
(C) Lactobacillus bulgaricus
(D) Acetobacter aceti

Answer 1

Hint: The milk is used by the people in many ways as raw milk, yogurt, cheese, butter and ghee. These products are obtained by changing the physical and the chemical properties of the milk. The products mentioned above are obtained by the continuous and the series of reactions.

Complete answer:
The production of yogurt is done by culturing the bacteria in the milk. When the milk is kept at proper temperature and when a small amount of yogurt is added, the bacteria present in the previous yogurt, start culturing in the milk and produce the lactic acid in it. This lactic acid formation causes the sour taste and the coagulation of the milk forming the curd.

The bacteria which are involved in converting the milk to curd are Streptococcus lactic, Streptococcus thermophilus and Lactobacillus bulgaricus. But the Acetobacter aceti is not used in yogurt production. This is useful to produce the vinegar by making the ethanol get converted into the acetic acid. Hence except Acetobacter all the others are used in the yogurt production.

Thus the correct answer is option (D).

Note:Basically these bacteria are present in the surrounding air. Hence when the milk remains unpreserved, these bacteria in the air enter the milk and start culturing itself. It is the spoiling of the milk. But some amount of the previous yogurt is provided into the milk, for the fast culturing of the bacteria.