We have done a few classes in chocolate in recent weeks, and so I spent some time this weekend experimenting with some of the things we’ve tried.
Chocolate is very odd stuff. Good dark chocolate consists only of cocoa solids, cocoa butter, sugar and probably a little vanilla and lecithin (an emulsifier) to help it all stay together. It is particularly the cocoa butter which gives chocolate such unique properties. It is solid at room temperature, but melts quickly at around body temperature, giving it those melt-in-the-mouth properties.
The fats in cocoa butter tend to form large crystals, which can be of 4 different types. Only one of these types, the beta crystals, is a stable form. When you buy chocolate, it is tempered, meaning that the fat is mostly in beta crystals. This means that the chocolate is shiny, will snap when you break it, and will melt at a slightly higher temperature (95F/ 35C). Once you melt the chocolate, other crystal types will prevail, and the cocoa butter might separate from the cocoa, forming white blotches or streaks (you sometimes see this when you leave a chocolate bar in the sun and then cool it down again).
So the trick is to melt the chocolate, so that you can make shapes, or truffles whilst maintaining that shiny glossy look of tempered chocolate. And let me tell you, it’s quite tricky! The idea is to melt the chocolate enough to disrupt all the crystals, then to cool it to just the temperature where the beta crystals will readily form, and then raise the temperature enough to melt any unstable crystals, but not so far as to melt the beta crystals.
As you can see from the photo, I was successful at least a couple of times. The particularly shiny finish is due to moulding the tempered chocolate in plastic moulds.