WHY DO CHAPATHI HAVE TWO LAYERS AFTER COOKINGThe wheat flour is mixed with salt and water and let to stand or rest for half an hour or more . The wheat flour then soaks up the water and gelatinizes. Gluten a protein in wheat absorbs water and forms a sticky network which gives the dough elasticity and helps it to stretch like a balloon. This is possible only by addition of water here. Oil too gives this elasticity.

This is not possible in flour which is mixed with water and immediately made into chapathis or rotis. However kneading the dough well increases the strength and spread of the gluten network in the dough. That is why “barotta masters” are seen kneading the dough.

When chapathis or rotis are rolled out the water trapped in the dough forms steam which is a gas. Many such gas pockets join together to rise up as a single unit of hot steam.

Meanwhile if you turn the chapathi it puffs up completely like a well filled cushion . Since the other side is already cooked the steam cannot break the layer and escape. So it stays there trapped between two layers.. The upper and lower layers. That is why you get two sheets of chapathi or roti. When cooled, the steam cools and the puff collapses but the two layers remain as their insides are cooked and cannot join together again.

The same thing happens in pooris, panipuris and bhaturas. Here too the dough should be rested or kneaded well if there is no time . In bhaturas a little yeast is also added.

But  if you dont let the dough stand for sometime or don't nicely beat it up or knead throughly like the shop cooks do, this steam may break the soft upper layer and escape. That's because in this case the wheat flour is not elastic enough. Then you get only one thick layer of chapathi with one or two small pockets of puffs or torn layers of escaped steam.