The Chemistry of Chocolate


If you’ve got a sweet tooth, like me, you’ll be interested in this article published in Chemistry World this month outlining the chemistry behind perfectly tempered chocolate.

Tempering of chocolate involves the alteration of the crystal structure of the cocoa butter within chocolate to the highly desired V polymorph, and maintaining this high-gloss state means tempering must be carried out every time chocolate is heated and manipulated.

With cocoa butter being able to crystallise in 7 different polymorphs, the temperature of the chocolate must be carefully controlled and held between 27 and 35 degrees Celsius to achieve the desired effect. The process sounds simple, but is in fact terribly tricky.

Indeed, Matt Hartings, who teaches the chemistry of cooking classes at  American University, Washington DC, states that ‘Chocolate is one of the more demanding things chemically to work with.’

The changing crystal structures of cocoa butter explains why chocolate tends to go white over time, as the more stable polymorph VI is formed, which diffuse light and give the paler, less glossy colour. They can even explain how flavour can be changed, as smaller crystals release flavour more slowly into the mouth. It’s then down to the organic molecules within the chocolate to fully define what the flavour will be like.

The article goes on to describe how water emulsions can be used instead of traditional chocolate fillings such as creams and butter to give a creamy sensation in the mouth without taking over the chocolate flavour and giving the chocolates fewer calories.

The chemistry of chocolate is more complex and more intricate than I’m sure many of us imagined, and I found it fascinating reading about the level of control and thought required to make high-quality chocolate.


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