How many of you like powered sugar donuts? Jelly filled donuts? I know I do. Boy howdy, do I. Have you ever noticed that when you bite into the donut it cools your mouth? I'd noticed this before, but never really thought much about it. I came across something interesting tonight in my reading.
But first a little background...dextrose is the dried form of glucose. Powered dextrose is also called "doughnut sugar" because it's better at coating things (like the front of my shirt) and doesn't dissolve easily. Now, onto the science!
"Dextrose crystals require a relatively large amount of energy to dissolve, because they are held together with strong bonds. When dextrose crystals are placed in the mouth, the energy needed to break the bonds and dissolve the crystals comes from the heat of the mouth. So much heat is needed that the temperature inside the mouth drops briefly, creating a cooling sensation."
-from How Baking Works by Paula Figoni