Properly fermented appam batter will have a light, airy texture with tiny bubbles throughout and a slightly sour aroma. It should have almost doubled in volume.
Fermentation is crucial for achieving the characteristic spongy center and crispy edges of appam. Here's how to check if your batter is ready:
Visual Inspection: Look for small bubbles throughout the batter. These bubbles are a sign that the yeast and bacteria are actively producing carbon dioxide, which creates the airy texture.
Volume Increase: The batter should have increased in volume, ideally almost doubling. This indicates sufficient gas production.
Texture: The batter should be light and fluffy, not dense or heavy. When you stir it, it should feel airy and slightly elastic.
Aroma: A slightly sour, fermented aroma is a good sign. It shouldn't smell overly yeasty or unpleasant.
Taste Test (Optional): You can taste a tiny amount of the batter. It should have a slightly sour taste, but not bitter or off-putting.
If the batter hasn't fermented enough, it will be dense, lack bubbles, and won't have the characteristic sour aroma. In this case, you can let it ferment for a few more hours in a warm place. If it has over-fermented, it will have a very strong sour smell and may have collapsed. Over-fermented batter can still be used, but the appams might be too sour.
The fermentation time depends on the ambient temperature. In warmer climates, the batter will ferment faster. In colder climates, you may need to place the batter in a warm spot, like near a stove or in a slightly warmed oven (turned off!), to encourage fermentation.