Noncrystalline sugar confections are the most hygroscopic of all centers. They readily pick up moisture from any source they contact, including centers with higher Aw, inclusions, or even the atmosphere. Once they pick up moisture, they gradually crystallize, destroying their quality. Noncrystalline sugar centers should only be combined with fat systems that contain no moisture unless great care is taken to protect them from damage. They must often be deposited while very hot; they should therefore be allowed to cool fully before they are layered with centers that are sensitive to heat, like gianduja or ganache.