Question

Renuka's mother made dosa batter. Instead of storing it in the fridge, she left the container with the batter in the kitchen overnight. While making breakfast in the morning, when Renuka opened the container, the batter was puffed up. What is the reason behind this?

• A. The batter must have absorbed moisture from the air and puffed up
• B. Renuka's mother must have added extra water in the batter
• C. Release of carbon dioxide by fermentative microbes growing in the batter must have caused the batter to puff up
• D. Renuka's mother must have added salt and extra rice in the batter

Answer 1

The correct option is C Release of carbon dioxide by fermentative microbes growing in the batter must have caused the batter to puff up

Many household food items like curd, dosa, idli, are made with the help of the fermentative activities of microbes.

Renuka's mother left the dosa batter (dosa batter is prepared by finely grinding the soaked rice and black gram) in a container overnight, before preparing the dosa, to allow it to ferment. Storing it in the fridge would have stalled microbial growth.

The microorganisms naturally present in the batter grow rapidly which ferment the sugars present in the batter and release carbon dioxide. The released carbon dioxide rises through the batter causing it to increase in volume and puff up.

The warmer room temperature causes faster fermentation due to the rapid growth of the microbes.

The addition of extra water or rice to the batter will disturb the right consistency that is needed to make the dosa but will not cause it to puff up.

Addition of extra salt would affect the taste of the batter but will not cause it to puff up.