How Great British Bake Off's Josh Smalley tempers chocolate

In 2023, Josh Smalley reached the final round of The Great British Bake Off, finishing with his showstopper bake, “A Slice For All Seasons”. However, Smalley is more than just a great baker, he is also a chemistry researcher at the University of Leicester, UK, and now runs a science kitchen, where he uses baking to teach fundamental chemistry theory, with delicious results. “I wanted to really try and use that little platform that I’ve got on the back of Bake Off to do something really good,” says Samlley.

The Science Kitchen is a really great way of showcasing chemistry and all the related sciences in the real world, Smalley explains when we visit his new lab. He shows us how to temper chocolate while explaining the chemistry that underpins it. In essence, through controlled heating and cooling, tempering isolates a particular crystal form of the cocoa butter, which has specific desirable properties. “It has a lovely snap, it has a beautiful sheen to it and it melts in the mouth,” says Smalley. This, he adds, is the same chemistry that applies to tempering metals. Then comes the reveal – we are learning through eating.