Chocolate should be kept in a cool, dry place. Heat can cause bloom, which is a grayish-white coating formed from the cocoa butter compounds separating and crystallizing on the surface. If the chocolate is used for baking, the bloom will disappear once the chocolate melts. Bloom can also arise from humidity. Sugar bloom, as this type is known, results when moist air draws the sugar to the surface, where it recrystallizes to form a gray substance. Unlike heat bloom, sugar bloom does affect taste ...