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) The CO2 released during respiration by the yeast results in the rise of dough.
(b) During anaerobic respiration, yeast produces alcohol resulting in sour smell.
(c) Sugar acts as food for yeast.
(d) At low temperatures, yeasts will not multiply and respire because of which the dough will not rise or become sour.