Fermenting batter
te: పులియబెట్టడం · hi: खमीर उठाना · en: fermentation
Why it matters
Idli and dosa batter is left overnight so that the wild yeasts and lactic bacteria that live on the rice and urad dal — and on your hands — feed on the starch. They produce carbon dioxide, which lifts the batter and makes idli soft and dosa lacy, and lactic acid, which gives the sourness and helps keep the batter. Nothing is added; the microbes come with the grain.
Fermentation is a question of warmth and time. In a Telangana summer, eight hours is plenty and twelve is too many. In a cold kitchen it may need a day, or a warm spot: inside the switched-off oven with the light on, or wrapped in a towel near the stove. The batter tells you when it is ready: it has risen by half or more, smells pleasantly sour, and is full of tiny bubbles when you stir.
Pesarattu is the exception among Telugu dosas — it is not fermented. Green gram batter is ground and used within the hour, which is why pesarattu is a same-morning breakfast.
Steps
- 1
Grind the batter a little thicker than you will cook it; it loosens as it ferments.
- 2
Add salt now if your kitchen is cold, later if it is hot — salt slows fermentation.
- 3
Mix the batter with your clean hand for a full minute; this adds air and the microbes that start the ferment.
- 4
Fill the vessel no more than half; the batter will rise. Cover loosely with a plate, not a tight lid.
- 5
Leave it in a warm, still place — 8 to 12 hours in summer, up to 24 in winter — and do not stir it while it works.
- 6
It is ready when it has risen by half, smells sour but clean, and shows bubbles when you tilt the vessel.
- 7
Stir gently once, then refrigerate; fermented batter keeps three to four days and turns sourer each day.
Tools
- Wide steel vessel with room to rise
- A plate to cover it loosely
- A warm corner of the kitchen