In spite of their high sugar content, crystalline sugar centers like fudge are not particularly hygroscopic. Crystalline centers resist moisture because the sugar they contain is in a crystalline—rather than amorphous—state. In fact, crystalline centers have a tendency to lose moisture to hygroscopic centers or inclusions, not to absorb it. Such centers are usually deposited while warm, and they give off further heat as they continue to crystallize. (See Latent Heat of Crystallization.) They must be allowed to cool completely before they are layered with centers like gianduja or ganache that cannot tolerate heat.