Blogging a crystal structure a day in 2014


Contributed by

Helen Maynard-Casely

The chocolate you don't want – cocoa butter form VI

What does it look like?

Image generated by the VESTA (Visualisation for Electronic and STructual analysis) software

Image generated by the VESTA (Visualisation for Electronic and STructural analysis) software

What is it?

We feature the structure of cocoa butter elsewhere. But unlike that first form (type V), you won't be too happy to find this arrangement of cocoa butter in your chocolate. This is type VI cocoa butter, which is the cause of fat bloom when chocolate heats up. We've all left a chocolate bar out in the sun at some point, seen it's gone a bit squidgy and popped it into the fridge – only to be disappointed later when eating it that it doesn't quite taste right. Part of the reason for that is that type VI cocoa butter has a higher melting temperature, so this one doesn't quite melt on our tongues. When tempering chocolate, it's important to keep the temperature at the right value to promote the crystallisation of the 'right' form, type V. There’s a super description of this process here.

Where did the structure come from?

This structure is from a paper by van Mechelen et al. This journal, one of those published by the International Union of Crystallography, makes it easy to access the 3D structures of all the structures published in it, you can play with the 'wrong' cocoa butter structures here.

Tags: cocoa butter   food   molecular