I, like most people, have wondered what makes fondant "melt" in the center of chocolates. In The Joy of Cooking, next to the recipe, they claim it's the egg whites. Just thought I would put that out there since I see the question all the time.
I don't know, but here is a bump for you!
Sugar, with any sort of moisture, will melt. Example, liquid center cherries. You wrap dry fondant mixture (mostly sugar) around a cherry and dip it in chocolate. In a relative short time, the fondant will absorb the moisture in the cherry and be liquid.