The traditional method for fermenting batter for Assamese 'pitha' involves using a clay pot (locally called a 'kalsi') and allowing the batter to ferment naturally at room temperature for 12-24 hours, depending on the weather.
The fermentation process is crucial for achieving the desired texture and flavor of Assamese 'pitha'. Here's a step-by-step breakdown of the traditional method:
Preparation of the Batter: The batter typically consists of rice flour (usually soaked and ground rice), water, and sometimes a small amount of baking soda or fenugreek seeds to aid fermentation. The consistency should be similar to that of pancake batter.
Using a Clay Pot ('Kalsi'): A clean, dry clay pot is essential. Clay pots provide a porous environment that encourages the growth of beneficial microorganisms responsible for fermentation. The pot is believed to harbor natural yeasts and bacteria that contribute to the unique flavor profile of the 'pitha'.
Fermentation Process: The batter is poured into the clay pot, leaving some space at the top as the batter will expand during fermentation. The pot is then covered with a clean cloth or lid to prevent contamination while still allowing air circulation.
Incubation: The pot is placed in a warm, undisturbed location in the kitchen. The fermentation time varies depending on the ambient temperature. In warmer weather, 12-18 hours may be sufficient, while in colder weather, it may take up to 24 hours or longer.
Checking for Fermentation: The batter is considered fermented when it has increased in volume, has a slightly sour aroma, and shows small bubbles on the surface. The consistency will also be lighter and more airy.
If you don't have a clay pot, you can use a glass or stainless steel container, but the flavor might not be exactly the same. Adding a small amount of leftover fermented batter from a previous batch can help kickstart the fermentation process and ensure a more consistent result.