Alum in the traditional food application mechanism

Mainly as a foaming agent role, because alum is containing 12 crystalline water aluminum potassium sulfate, heating will lose water to produce bubbles, in addition and alkali can generate aluminum hydroxide and so on, is not it can also foam ah? ~~~~ just don't eat more of this food is good, because too much aluminum intake will make people get Alzheimer's drops oh ~~~~~~~:)