Introduction:
Curd and idlis are both popular food items in India. Curd is a dairy product made by fermenting milk, while idlis are a type of steamed rice cake made by fermenting a batter of rice and lentils. Both curd and idlis are examples of fermented food.

Fermented food:
Fermentation is a natural process that involves the breakdown of carbohydrates by microorganisms like bacteria, yeast, or fungi. This process produces beneficial compounds such as organic acids, vitamins, and enzymes, which enhance the nutritional value and taste of the food. Fermented foods are known to have several health benefits and are an integral part of many cuisines worldwide.

Why curd is a fermented food:
Curd is made by adding a culture of beneficial bacteria, typically lactobacillus, to milk. These bacteria convert the lactose (milk sugar) in the milk into lactic acid through fermentation. This fermentation process gives curd its tangy taste, creamy texture, and characteristic aroma. The presence of lactic acid also helps in improving digestion and promoting the growth of healthy gut bacteria.

Why idlis are a fermented food:
Idlis are made by soaking and grinding a mixture of rice and lentils. This mixture is then left to ferment overnight or for a few hours. During fermentation, the naturally present microorganisms on the rice and lentils convert the carbohydrates into organic acids, carbon dioxide, and alcohol. The carbon dioxide produced creates air pockets in the batter, making the idlis light, fluffy, and spongy. Fermentation also enhances the nutritional value of idlis by increasing the bioavailability of certain nutrients and improving digestibility.

Conclusion:
In conclusion, curd and idlis are both examples of fermented food. The fermentation process involved in making curd and idlis not only enhances their taste and texture but also provides various health benefits. Including fermented foods like curd and idlis in our diet can contribute to a healthy digestive system and overall well-being.