DT Next Campus: The physics of crispy dosas
Formally discovered in the 18th century in Germany, the Leidenfrost effect has helped make dosas for centuries. It is nothing but science in action
Prof Mahesh Panchagnula
CHENNAI: The kitchen is alive with the morning bustle. The heavy iron pan sits on the stove, slowly heating, while the familiar smell of dosa batter fills the air. Before she does anything else, Grandma reaches for a small bowl of water.
With a practised flick, she sprinkles a few drops onto the pan. You lean closer and watch carefully. At first, the droplets just sit there and fizzle into steam.
Grandma smiles knowingly — “Not yet,” she says. A minute later, she tries again. This time, the water beads leap up and skitter across the pan like tiny dancers.
“Now,” she nods, and only then does she ladle the batter onto the surface, spreading it thin in a swift, circular motion.
What you just witnessed is science in action — the Leidenfrost effect. Formally discovered in the 18th century in Germany, this effect has, however, helped make dosas for centuries before.
When a surface is heated beyond a certain temperature, droplets of water no longer stick and evaporate quietly. Instead, they form a thin cushion of vapour that keeps them from touching the hot surface directly. That’s why they dance around on Grandma’s pan.
And that same effect is what ensures her dosa doesn’t stick. If the pan is too cool, the batter clings stubbornly, tearing into messy lumps. If it’s too hot, the batter never grips at all, leaving burnt spots and holes. But at just the right temperature, the pan is hot enough to keep the batter from sticking, yet not so hot that it floats away. The result? A dosa that is crisp at the edges, soft in the centre, and perfect all around.
So the next time you eat a dosa, remember Grandma’s little ‘dance test’. It’s not just a tradition — it’s physics, making your breakfast possible.
(THE AUTHOR: Prof. Mahesh Panchagnula is a Professor in the Department of Applied Mechanics and Biomedical Engineering, IIT Madras. He is also the Head, Center of Excellence on Sports Science and Analytics)
You can listen to his podcast in the following link - https://www.youtube.com/@ProfMaheshPodcast
