IIT-Madras professor explains why dosas are crispy on outside & soft on inside
Dosa, a traditional Indian dish, has been a staple in many households for centuries. The crispy exterior and soft interior of a perfectly cooked dosa have always been a topic of fascination for food enthusiasts. Recently, Prof Mahesh Panchagnula from IIT-Madras shed light on the science behind the perfect dosa, explaining why it is crispy on the outside and soft on the inside.
The secret to a perfect dosa lies in the way it is cooked on a hot tawa. The practice of sprinkling water on the hot tawa before pouring the dosa batter is a common technique used by many cooks. But have you ever wondered why this technique is so important? According to Prof Panchagnula, this practice is linked to a phenomenon known as the Leidenfrost Effect.
The Leidenfrost Effect was first identified in Germany in the 18th century by Johann Leidenfrost. It 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 does not immediately evaporate. Instead, it forms a thin layer of vapor between the water droplets and the hot surface. This layer of vapor reduces the heat transfer between the water and the surface, allowing the water to float on top of the vapor layer.
In the context of cooking a dosa, the Leidenfrost Effect plays a crucial role. When the tawa is not hot enough, the water sprinkled on it evaporates slowly, and the dosa batter sticks to the surface. However, when the tawa is heated to the right temperature, the water glides and floats on a thin vapor layer, preventing the dosa from sticking to the surface. This is what gives the dosa its characteristic crispiness on the outside.
But how does the dosa remain soft on the inside? The answer lies in the way the heat is transferred to the dosa batter. When the dosa is cooked on a hot tawa, the heat is transferred to the batter through a process known as conduction. The heat from the tawa is conducted through the dosa batter, cooking it evenly. However, the heat transfer is not uniform, and the surface of the dosa batter is cooked more quickly than the interior.
As the surface of the dosa batter is cooked, it becomes dry and crispy, while the interior remains soft and moist. The starches in the batter absorb the water and swell, creating a soft and fluffy texture. The combination of the crispy exterior and the soft interior is what makes a perfectly cooked dosa so delicious.
Prof Panchagnula’s explanation of the science behind the perfect dosa has sparked a lot of interest among food enthusiasts. The use of the Leidenfrost Effect to explain the crispiness of the dosa exterior has shed new light on the traditional cooking technique. It has also highlighted the importance of temperature control in cooking a perfect dosa.
In conclusion, the perfect dosa is a result of a combination of factors, including the right temperature, the use of the Leidenfrost Effect, and the even transfer of heat to the dosa batter. The next time you cook a dosa, remember the science behind the perfect crispiness on the outside and softness on the inside. And if you are struggling to get the perfect dosa, try adjusting the temperature of your tawa and sprinkling a little water on it before pouring the batter.
News Source: https://x.com/iitmadras/status/1993901259925909929
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