Yes, dosa batter can be stored in the fridge after fermenting. Refrigeration slows down the fermentation process, preserving the batter for later use.
Once your dosa batter has fermented to your liking (typically indicated by a slight sour smell and increased volume), you can transfer it to an airtight container and store it in the refrigerator. The cold temperature significantly slows down the activity of the microorganisms responsible for fermentation. This prevents the batter from becoming overly sour or developing an undesirable taste. Properly refrigerated dosa batter can typically last for 3-4 days. Before using the refrigerated batter, allow it to sit at room temperature for about 30 minutes to an hour. This will help to slightly reactivate the fermentation process and improve the texture of your dosas. Give the batter a gentle stir before using, as some separation may occur during refrigeration. If the batter appears too thick after refrigeration, you can add a small amount of water to achieve the desired consistency.
To further extend the shelf life of your dosa batter, consider freezing it. Divide the fermented batter into smaller portions and freeze them in airtight containers or freezer bags. Thaw the batter in the refrigerator overnight before using, and remember that the texture might be slightly different after freezing and thawing.