Does anyone know why if you let Ovaltine sit out for a litle while, it turns pink?

Answer 1

Yes I do. Ovaltine is supplemented with iron, not a ton but enough if left out it will oxidize and turn pink. It appears pink and not red because of the color of the milk tends to dilute the sharp red color. In the lab we also observed this, but there isn't a whole lot one can do about it. When packing the dry powder out in cans nitrogen gas is entrained in the product to prevent oxidation of the iron and other minerals in the powder, so when you open the can, it is not red or some other color. It will not harm you and in no way affects the product negatively.

Answer 2

It's probably the red food color in the product, separating and leaking into the milk, giving it a pink hue.