Chana dal. Why skim off the white foam?

As for microscopic dust, isn't that what we take in every time we inhale? I'll trust the aunties.

Just to clarify -- I was thinking about regular white chickpeas (for chana masala, chole etc) but the same goes for chana dal, which is (I think!) the split black chickpea. I've never skimmed any dal, to no ill effect.

I have watched many an auntie make chana in North India, and I don't know anyone who would skim it -- they all made it in pressure cookers. They would just rinse the chickpeas well, soak them overnight, rinse again and then throw them in the pressure cooker the next day.

I was always lead to believe that the reason for both rinsing and skimming was that it would help to reduce the.... Flatulent qualities of the lentils/split peas etc... I could be completely wrong, but figure it best to do what I've been taught on that one!

Thanks everyone! I will try not skimming (and I do thoroughly wash the dal before cooking) and see if I notice a difference in flavor. I will report my findings!

The foam is denatured protein from the lentils. Its not harmful, but the soapy nature tends to accumulate microscopic dust etc that may have been sticking to the dals

As to what the foam is, I don't know. I've looked at several recipes for chana dal that do not call for skimming the foam, so I can't imagine it's harmful. I say, don't skim it and see how it goes. If you think it tastes better with skimming you can always do so in the future, but if you can't tell a difference then you can just save yourself the hassle from now on.