Idli is healthy food that is made of rice or sooji batter through a process called Fermentation.
Fermentation is a science that happens with the rapid growth of micro-organisms. Hot steamy sambhar and fluffy idli are marvellous quick fix for chilly mornings. Fermentation makes food light on tummy and make food easily digestible. We make idli batter a night before, grind pulses and rice night before and let it ferment overnight. Perfect fermentation is essential for perfect fluffy idlis.
Before going into the details of the science behind Fermentation, let’s take a quick review on how Idli is made. For quicker result, one can also add ENO which is a fruit salt, but slow overnight fermentation is preferred as it is good from nutrients perspective too.
Traditional Form of Making Idlis
1. Take desired quantity of rice and urad daal (black gram), and soak them separately in water overnight
2.Drain excess water, grind rice and black gram separately with occasional addition of water during grinding process
3. Two batters are then mixed together with addition of a little salt
4. Keep mixture to ferment overnight at room temperature
5. Fermented batter is dispensed in special idli pans and allowed for steaming for 5–8 min
Science of Fermentation of Idli
Overnight fermentation of idli batter allows the rapid growth of the naturally occurring microorganisms viz. Leuconostoc mesenteroides and Streptoccous thermophilus in grains/legumes/utensils. These microorganisms divide and produce lactic acid and carbon dioxide that make the batter anaerobic and leaven the product. Bubbles of carbon dioxide form a Froth on top of the fermentation mixture.
You can add small amount of yeast also which helps in fermentation and the batter comes out very nice resulting into best idlis.
Changes during fermentation are highly significant for nutritional point of view:
- During fermentation, vitamins B (Riboflavin, Thiamine and folic acid) and Vitamin C increase.
- Increase in free sugar, non-protein nitrogen, free nicotinic acid, methionine and chlorine
- Phytate is hydrolyzed almost to 50%
- An increase in methionine, a limiting essential amino acid in legumes, greatly improves protein value