Thank the chemists for Violet Crumble

An Aussie favourite is the delicious Violet Crumble—similar to a Crunchie chocolate bar, but with lighter and more friable honeycomb.

The Violet Crumble bar was invented by Abel Hoadley, who originally made jams and pickles. He branched out into making confectionery, and the Violet Crumble’s humble beginnings were a simple piece of honeycomb on its own among an assortment of chocolates. The popularity of the honeycomb made Hoadley decide to make and sell it on its own. There was a problem though—the hygroscopic (water-loving) nature of the honeycomb meant that it absorbed moisture from the air, making it sticky.

The solution? Chocolate! By coating the honeycomb in a layer of delicious chocolate, Hoadley was not only creating the amazing choc-honeycomb taste sensation, but also giving the honeycomb a protective barrier that prevented it from absorbing moisture and turning gooey.

Photo of melted chocolate on a spoon — Chocolate is often the answer to problems, especially if the issue is keeping honeycomb from absorbing water and becoming sticky. Image adapted from: Peter Pearson; CC BY-SA 2.0 .

The great thing about this one is that you can make it yourself! It probably won’t taste exactly like a Violet Crumble, but you will end up with a delicious sweet treat and it’s fun to make. What makes it fun? Chemistry again. The process involves heating sugar to boiling point, then adding bicarb soda (sodium bicarbonate—NaHCO₃). The heat of the sugar syrup makes the bicarb break down in what’s called a thermal decomposition reaction, releasing carbon dioxide gas (CO₂) that causes the mixture to froth and foam spectacularly. The chemical reaction is:

There are lots of recipes on the internet—choose one that uses glucose syrup rather than honey or golden syrup if you prefer a lighter honeycomb.