Question

A food stall owner was preparing dough for making bhaturas. He added a pinch of yeast and sugar to the dough and left it in a warm place. After few hours, the dough had risen. There was a sour smell too.

(a) Why did the dough rise?

(b) Why did the dough smell sour?

(c) Why was sugar added to the dough?

(d) What would have happened if the dough was kept in the refrigerator, soon after it was prepared?

Answer 1

a) Yeast:

1. Yeast are the single cell organisms which perform anaerobic respiration.
2. The dough rose because of the release of carbon dioxide which is a product of anaerobic respiration.
3. In anaerobic respiration, glucose is broken down to produce energy, carbon dioxide and alcohol.

b) The dough had a sour smell because of the production of alcohol in it.

c) A little bit of sugar is added to the dough as yeast feeds upon the sucrose present in it and produce carbon dioxide, thus amplifying the fermentation process.

d) If the dough is kept in refrigerator as soon as it is prepared there would be no change in it because yeast needs warm culture to proliferate and multiply but there is low temperature inside a refrigerator, which would inhibit the growth of yeast.