A lot of recipes for biryani involve sealing the edges of the pot with dough. I generally used a kitchen towel and weigh down the lid with something heavy and don't bother with the dough. I was wondering if there is any benefit to using the dough over the towel.
I use the towel method for some other rice dishes as well as I find the towel helps to absorb some of the moisture as opposed to it condensing on the lid of the pot and dripping back in.
I have used both methods. I don't really know why but the one cooked with dough tasted bit better than kitchen towel method for me.
I believe it was because the container was sealed very well and no room for air to escape. The meat is cooked to perfection too.
You are right the towel absorbs moisture which may even dry out the rice and meat so moisture is important for slow cooking.
A dough seal is a good way to stop (most)steam from escaping the dish, but kitchen towel is a poor substitution. It is pretty porous and will stop very little steam when its wet. Heavy thing on the lid will not work good too because the lid and pot does not match 100% in the edges, leaving channels where steams escape.
Another way is to put the lid on and crumple aluminium foil around the pot-lid edge, this works much better than kitchen towel.
Keeping steam in the pot ensures the rice and meat are succulent inside.
