Hi! i know what glycerin is used for as i have seen it in fondant recipes, but what does it do, specifically? i always thought knowing the science behind something helps a person be better at their craft, yes?
Glycerin is a very mild sweetener, and may help preserve foods.
Primarily, it helps hold in moisture and makes the fondant soft & pliable. It's used in soaps and hand lotions for the same reason.
I keep a bottle of glycerin handy to add a few drops to gel food colors that have gotten thick or dried out a bit. Stir, stir, stir! It helps to get them back to a usable state.