Chocolate has a very low melting point and will melt at 40-50°C. Therefore, the chocolate is usually melted by heating with insulated water. If heated on direct fire, it is likely to scorch, so be very careful. Chocolate has poor thermal conductivity and needs to be cut into relatively uniform pieces to accelerate melting. Aside from temperature, the biggest enemy of chocolate is water. Mix a small amount of water in melted chocolate, and the water gets locked in the chocolate and solidifies into a lump, producing small hard lumps. Unless you add a lot of high-temperature liquid, it becomes a chocolate sauce, like a ganache.
The cocoa butter in chocolate is composed of a variety of fatty acids. It begins to soften at 28°C and melts into a liquid at 33°C. Its freezing point and melting point are very narrow. Do we hold the chocolate in our hands or is it solid and melts in the mouth for a while? It is because the body temperature promotes the transformation of cocoa butter from solid to liquid. The properties of cocoa butter are the most important properties of chocolate.
The optimum temperature for chocolate storage is 15-18°C. After the chocolate is stored for a period of time, the surface will turn white and look like a layer of frost. This is the fat bloom, which is the crystallization of cocoa butter, commonly known as oil spots. This is because unstable cocoa crystals melt and move to the surface, where they recrystallize. Chocolate needs to be tempered. The surface point is to make the chocolate look better at room temperature, taste better, avoid oil spots, and facilitate reshaping.