Why does fine powder (like flour or powder milk) mixes evenly when stirred in cold water, but not in hot water (where the mixture becomes lumpy)?

Question

Why does fine powder (like flour or powder milk) mixes evenly when stirred in cold water, but not in hot water (where the mixture becomes lumpy)?

In: Chemistry

Answer 1

Because hot water causes starches to expand like inflatable spring snakes. They end up getting tangled together and you end up with clumps. Cold water allows the mixture to evenly distribute themselves before expanding.