Over-fermenting dhokla batter results in a sour taste, a collapsed or dense texture, and an unpleasant ammonia-like smell, making the dhokla unappetizing.
Dhokla batter relies on fermentation to create its characteristic light and fluffy texture. During fermentation, microorganisms, primarily bacteria and yeast, consume sugars in the batter and produce carbon dioxide gas. This gas creates air pockets, giving dhokla its spongy quality. However, if the fermentation process goes on for too long, several undesirable changes occur.
Firstly, the bacteria produce excessive amounts of lactic acid and other acidic byproducts, leading to a sour or acidic taste that overpowers the other flavors. Secondly, the gluten structure in the batter weakens due to prolonged enzymatic activity. This causes the dhokla to collapse during steaming or result in a dense, less airy texture. Finally, over-fermentation can lead to the production of ammonia, resulting in an unpleasant smell and taste. The ideal fermentation time depends on the ambient temperature and the specific recipe, but it's crucial to monitor the batter and steam it when it has risen sufficiently and has a slightly tangy, but not overly sour, aroma.
To prevent over-fermentation, especially in warm climates, refrigerate the batter after it has fermented for the recommended time. This slows down the fermentation process significantly, allowing you to steam the dhokla later without compromising its taste and texture.