Question

Which of the following is correct about fermentation?
A. Bread gets fermented due to formation of lactic acid.
B. Pulled up appearance of dough is due to production of $C{O_2}$.
C. Fermentation in muscles produces alcohol.
D. Both A and B.

Answer 1

The metabolic process which produces chemical changes in an organic substrate by the action of enzymes can be termed as Fermentation. Fermentation has been used by humans since the Neolithic age to produce foodstuffs and beverages. The process of fermentation can also occur within the gastrointestinal tracts of all animals, which includes humans.

Complete answer:
Option A Bread gets fermented due to formation of lactic acid: The process of lactic acid fermentation takes place in some strains of bacteria and in skeletal muscle and produces lactic acid. But for making bread, usually yeast is added. In yeast, alcoholic fermentation takes place and produces ethanol and carbon dioxide.
So, there is no formation of lactic acid in bread production and option A is not correct.
Option B Pulled up appearance of dough is due to production of $C{O_2}$: In bread making, during the process of fermentation, yeast feeds on the sugar contained with the dough which produces carbon dioxide and alcohol. The Carbon dioxide produced is trapped as tiny pockets of air within the dough. This causes the dough to rise. At the time of baking, carbon dioxide expands and the bread rises further.
Hence option B is the correct answer.
Option C Fermentation in muscles produces alcohol: The process of fermentation in muscle cells produces a lactic acid, which builds up during intense exercise. Lactic acid buildup contributes to fatigue in muscles.
Hence option C is not correct.
Option D Both A and B: Even though option B is correct, option A is not correct.
Hence option C is also not correct.

So, Option B. Pulled up appearance of dough is due to production of $C{O_2}$, is the correct answer.

Note:
Dough is left in a warm place during the process of bread making. The heat causes the fermentation process to take place. But, if the temperature is raised too high during the cooking process, yeast gets killed. The alcohol produced during fermentation gets evaporated during the process of baking bread. The characteristic flavors and aroma of bread is due to alcohol produced by the yeast during fermentation along with a multitude of other reactions.