There is no need to skim the foam on boiled soybean milk. It is harmless. However, it will cause the phenomenon of false boiling of soybean milk. So when you see the foam appear, do not turn off the fire. You should first heat it with a small fire to remove the foam and then heat the soybean milk to boiling.
When we beat soybean milk manually, we will find that a large amount of floating foam will appear on the surface when heating soybean milk. It is said that it is the essence of food, and it is also said that it is a poisonous substance.
In fact, the floating foam of boiled soybean milk is due to a component called saponin in soybean. It has no problem in itself. There is no problem if you don't want to throw it away, but its appearance will cause false boiling of soybean milk.
So when we see the foam appear, do not turn off the fire immediately, because this will cause the soybean milk to be heated thoroughly. We should first adjust the fire to the small fire until the foam has disappeared, and then the soybean milk will be heated to boil until it is ready to drink.