I don't if other countries has them, but Galaxy just melts in my mouth!
Anything that doesn't melt in the mouth can't be chocolate. The chemical feature that makes cocoa butter virtually unique among animal and vegetable fats and oils is that it is mainly composed of a single triglyceride, which has the old-fashioned name of palmito-, oleo-, stearin (it does have a modern systematic name, but it's so long that you might fall asleep before you finished reading it or I might fall asleep before I finished typing it).
This means that cocoa butter has a relatively sharp melting point, unlike all the other fats and oils which are mixtures of many triglyceride molecules, so they slowly get softer if the temperature rises, like butter, or throw down solids if the temperature drops, like olive oil. Moreover, cocoa butter melts a little below 37°C (blood temperature): so it melts in your mouth, but not on your skin, which is rather cooler.
Confectioners aim to mix cocoa butter with cheaper fats to reduce the cost of a chocolate bar, without adding so much that the chocolate softens at too low a temperature. The taste of the chocolate comes from traces of other chemicals in the cocoa butter. The added fats are virtually tasteless, so the flavour is boosted by adding cocoa powder, which is basically the residue of the cocoa beans after the cocoa butter is extracted. I think that white chocolate stays white and has a milder flavour because no cocoa powder is added to it. Sugar is also usually added, along with other flavourings, milk powder etc. These components are melted together, mixed thoroughly and then cooled slowly ('tempered') to prevent them crystallising separately as the chocolate solidifies.
Very simple science really
Alan
