Okay, one (1) person asked for this infodump, so here goes! Ever wondered why people temper chocolate (heating and cooling it to very specific temperature ranges) to make it shiny, and why it’s such a fiddly process? Or why chocolate sometimes goes crumbly and dull? Well, it’s all to do with the structure of the cocoa fats.
Triglyceride molecules are shaped like this:
And it turns out that there are lots of possible ways that you can “stack” molecules that are shaped like that:
(This is from Stuff Matters by Mark Miodownik, it’s an excellent little book on basic materials science)
The structures like the ones on the left, where the molecules are quite loosely packed together, are separated either by force or by applying heat, which means that they tend to be quite crumbly in texture and have lower melting points.
The structure on the right, where the crystals are super densely packed together, is what we’re after when we temper chocolate. It is shiny, it doesn’t crumble and has a nice “snap”, and , best of all, its melting point is very close to that of the human body, so it starts to melt as soon as it touches your mouth. Fundamentally, that’s what’s so special about chocolate, why we love it so much.
And speaking of melting points, the lower grade crystals on the left are useful in chocolate chip ice creams, because the lower melting point means that it will also melt in your mouth, and it doesn’t matter that it isn’t shiny.
