Chocolate contains cocoa butter, a vegetable fat that is sensitive to heat and humidity. Temperatures above 75°F will cause chocolate to melt. The cocoa butter can rise to the surface and form a discoloration called "cocoa butter bloom." Condensation on milk or semi-sweet chocolate may cause the sugar to dissolve and rise to the surface as "sugar bloom." Chocolate that has "bloomed" is certainly safe to use, but flavor loss and texture changes may be noticed.