Question

why does there is appearance of yellow colour after sometime on surface of boiled milk?

Answer 1

the ghee of the milk is comes out so the colour of ghee is yellow. If you boil for more time the ghee will come out (all).

Answer 2

There was a gallon of milk in my fridge that turned yellow, and I can't figure out why. It is still several days before the expiration date. It didn't freeze. It didn't smell weird. I can't figure it out. It is now down the drain, but the mystery is bothering me. Google only tells me that milk turns yellow when frozen and back to white when thawed, so that is not helpful.