IIT-Madras Professor Explains Why Dosas are Crispy on the Outside and Soft on the Inside
The dosa, a staple of South Indian cuisine, has been a topic of fascination for food enthusiasts and scientists alike. The unique texture of a dosa, crispy on the outside and soft on the inside, has puzzled many. Recently, Prof Mahesh Panchagnula from IIT-Madras shed light on the science behind this phenomenon. In a fascinating explanation, he revealed that the key to achieving the perfect dosa texture lies in the practice of sprinkling water on a hot tawa before pouring the dosa batter. This practice, he explained, is linked to the Leidenfrost Effect, a phenomenon identified in Germany in the 18th century.
For those who may not be familiar, the Leidenfrost Effect is a phenomenon where a liquid, in this case, water, comes into contact with a surface that is significantly hotter than its boiling point. When this happens, the water evaporates rapidly, creating a thin layer of vapor between the water and the hot surface. This vapor layer reduces the contact between the water and the surface, allowing the water to glide and float on top of the vapor. This effect is named after Johann Leidenfrost, a German scientist who first observed and documented this phenomenon in 1756.
Now, let’s apply this concept to the art of making dosas. When a hot tawa is sprinkled with water, the water droplets come into contact with the hot surface. If the tawa is not hot enough, the water evaporates slowly, and the dosa batter sticks to the surface. However, when the tawa is heated to the right temperature, the water droplets create a thin vapor layer, allowing them to glide and float on top of the vapor. This is where the magic happens.
As the dosa batter is poured onto the tawa, it comes into contact with the hot surface, but the vapor layer created by the water droplets prevents the batter from sticking. The heat from the tawa cooks the dosa batter, causing it to crisp up on the outside, while the inside remains soft and fluffy. This is because the vapor layer created by the Leidenfrost Effect allows for a gentle and even heat transfer, cooking the dosa batter uniformly.
But that’s not all. The Leidenfrost Effect also plays a crucial role in preventing the dosa from becoming too crispy or burnt. As the dosa cooks, the vapor layer continues to reduce the contact between the dosa and the hot surface, preventing the formation of a hard, crusty layer. This ensures that the dosa remains crispy on the outside, while maintaining a soft and delicate interior.
In addition to the Leidenfrost Effect, there are other factors that contribute to the perfect dosa texture. The type of batter used, the temperature of the tawa, and the cooking time all play a crucial role in achieving the perfect balance of crispiness and softness. However, the practice of sprinkling water on a hot tawa before pouring the dosa batter is a critical step in creating the ideal conditions for the Leidenfrost Effect to occur.
In conclusion, the science behind the perfect dosa texture is fascinating, and the Leidenfrost Effect plays a crucial role in achieving the ideal balance of crispiness and softness. By understanding the science behind this phenomenon, we can appreciate the art of making dosas in a whole new light. Whether you’re a seasoned chef or a culinary enthusiast, the next time you make dosas, remember the Leidenfrost Effect and the importance of sprinkling water on a hot tawa before pouring the batter.
Source: https://x.com/iitmadras/status/1993901259925909929
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