If one of your favourite chocolate bars is a Cadbury’s Crunchie, then you’ve probably spent a lot of time staring at those holes and bubbles inside it before you take your next bite. How do the bubbles get there? How are Crunchie bars made?
The bubbly centre underneath all that delicious chocolate is called honeycomb. It’s also called cinder toffee or hokey pokey. So let’s learn how make some honeycomb and find out the science behind the bubbles.
- 100g caster sugar
- 2 1/2 tbsps golden syrup (about 45g weighed out)
- 1 tsp bicarbonate of soda
- Large saucepan
- Wooden spoon
- Greaseproof paper on a tin/baking tray
Making homemade honeycomb requires standing at a hob and the temperature of the sugar mix in the pan gets really hot. Please make sure that a grown-up is with you at all times, and NEVER touch the contents or the pan.
Let’s Get Going
1.Put your sugar and golden syrup into your saucepan.
3. Continue to heat gently and stirring often. The mix will start to bubble.
4. Keep your eye on the color of the syrupy mix in the pan. Once it starts to turn to a darker, more maple syrup type of brown, then get a grown-up to remove it from the hob. This takes between 5-10 minutes. If you have a sugar thermometer you need to wait until the temperature gets to the hard crack stage.
5. Add your bicarbonate of soda and stir it in. You’ll see the mix transform instantly into a puffy mass. Once it’s all stirred in, get a grown-up to transfer your honeycomb mix to the greaseproof paper quickly.
TIP: This will make pieces of about 1cm or so in depth. If you want chunkier pieces, then put your greaseproof paper inside a loaf tin and put your mix in there to stop the mix from spreading.
6. When the honeycomb has cooled (about 1 hour), tap it with the back of a spoon to break it up into golden pieces. You can dip these in melted chocolate, to make them just like a Crunchie bar, or eat them as they are. Keep them in an airtight container either way.
You’ve probably worked out that it’s the bicarbonate of soda that is the magic ingredient in honeycomb.
Because the sugar mix is so hot, it gets working with the bicarbonate of soda straight away. The heat from the sugar mix breaks down the bicarb, forcing it to release carbon dioxide (a kind of gas) immediately. This gas is what causes the bubbles in honeycomb, and the bubbles make the mix expand to create the light, bubbly texture we know as honeycomb.
We only used a teaspoon of bicarb in our recipe, but what do you think would happen if we added twice as much bicarbonate of soda? Post your guesses below, or maybe even try it and let us know how you get on! (HINT: You might need a bigger pan.)