Why does chocolate melt in your mouth?

Cocoa butter, the fat in chocolate, can crystallise in six different forms, each with a different melting point. Chocolatiers use a process called tempering, heating and cooling the chocolate carefully, to produce Form V crystals, which melt at about 34°C. Our mouths are around 37°C, so well-tempered chocolate melts smoothly on the tongue while staying snappy and glossy at room temperature. Poorly stored chocolate can develop a white coating called bloom when fat or sugar rises to the surface. It is safe to eat but has a dull, crumbly texture.