IIT-Madras professor explains why dosas are crispy on outside & soft on inside
Dosa, a traditional South Indian dish, has been a staple in many Indian households for centuries. The crispy exterior and soft interior of a perfectly cooked dosa is a delight to the senses. However, have you ever wondered what makes a dosa crispy on the outside and soft on the inside? A professor from the Indian Institute of Technology (IIT) Madras has shed some light on this age-old question.
Prof Mahesh Panchagnula, a professor at IIT-Madras, has explained the science behind the perfect dosa. According to him, the practice of sprinkling water on a hot tawa before pouring the dosa batter is linked to the Leidenfrost Effect. This phenomenon was first identified in Germany in the 18th century by Johann Leidenfrost. The Leidenfrost Effect is a physical phenomenon in which a liquid, in this case, water, comes into contact with a surface that is significantly hotter than its boiling point. This causes the water to evaporate rapidly, creating a thin layer of vapor between the liquid and the surface.
When the tawa is not hot enough, the water evaporates slowly, and the dosa batter sticks to the surface. However, when the tawa is at the right temperature, the water glides and floats on a thin vapor layer, preventing the dosa from sticking. This is the key to creating a crispy exterior and a soft interior. The vapor layer acts as a barrier between the dosa and the tawa, allowing the dosa to cook evenly and preventing it from sticking.
The Leidenfrost Effect is not unique to dosas, and it can be observed in many everyday situations. For example, when you sprinkle water on a hot skillet, you may have noticed that the water droplets seem to dance on the surface before evaporating. This is also an example of the Leidenfrost Effect.
So, how can you apply this knowledge to make the perfect dosa? According to Prof Panchagnula, the key is to heat the tawa to the right temperature. If the tawa is too hot, the dosa will burn, and if it’s too cold, it will stick. The ideal temperature for cooking a dosa is around 200-250°C. Once the tawa is heated to the right temperature, sprinkle a few drops of water on the surface. If the water droplets glide and float on the surface, you know the tawa is ready for cooking.
Another important factor in making the perfect dosa is the batter. The batter should be of the right consistency, neither too thick nor too thin. If the batter is too thick, the dosa will be dense and heavy, and if it’s too thin, it will be fragile and prone to tearing.
In addition to the Leidenfrost Effect, there are other factors that contribute to the crispy exterior and soft interior of a dosa. The type of rice and lentils used in the batter, the ratio of rice to lentils, and the fermentation process all play a crucial role in determining the texture and flavor of the dosa.
In conclusion, the secret to making the perfect dosa lies in the combination of the right temperature, the right batter, and the right technique. By understanding the science behind the Leidenfrost Effect and applying it to the cooking process, you can create a crispy exterior and a soft interior that will delight your taste buds. So, the next time you cook a dosa, remember to sprinkle a few drops of water on the hot tawa and watch as the magic unfolds.
News Source: https://x.com/iitmadras/status/1993901259925909929
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