Did you know there’s chemistry involved in making candy? Candy requires the making of what is called a “supersaturated solution.” In a nutshell, when it comes to making candies, that means dissolving more sugar into a liquid than would normally be possible by using heat! With winter break coming up, and many families taking it easy at home due to the pandemic, now is a great time to engage in some fun chemistry experiments that reward kids for doing STEM with a treat they can eat.
Because of the temperatures involved in candy making and the risk of accidental burns, all of these experiments should be under adult supervision. But beyond that, all you need is a grocery list and a candy thermometer to get started. Be sure to test your thermometer in a pot of boiling water when you get started. Water boils at 100 degrees Celsius at sea level, so you may have to note any difference in your thermometer reading and adjust accordingly.
Chemistry experiments never tasted so sweet.
1 – The Sugar Stages of Candy Making
The first step in making any candy is understanding that there’s 7 stages based on the temperature and the concentration of sugar: Thread, Soft Ball, Firm Ball, Hard Ball, Soft Crack, Hard Crack, and Caramelization. Here’s a handy guide to the different types of stages.
Different kinds of candy require different concentrations of sugar, because the different concentrations make the candy behave in different ways when it cools. You can try making all seven to see how a supersaturated sugar solution behaves at different concentrations! It’s pretty cool to see how the same solution with more or less water can become completely different kinds of candy.
2 – Homemade Lollipops
When making lollipops and “glass candy,” a simple syrup will need to be brought all the way up to the hard crack stage – a 99% sugar solution very close to caramelization, so be careful not to go over!
These freeform “Psychedelic Lollipops” from Food Network require no special mould, but you can get moulds if you want to make lollipops in certain shapes. Just be certain that you’ve ordered a mould meant for hard candy, as this syrup will be extremely hot.
3 - Make your own Peppermint Rock Candy!
Rock candy is cool on so many different levels – you not only need to make a supersaturated solution, but you also get to observe how crystals can form over time right on your own countertop. This experiment takes a couple of weeks to pay off… but this recipe from Food & Wine is also great to give away as gifts to dip in cups of hot cocoa and other hot drinks for the holidays.
4 – Fudge
Did you know fudge is candy too? The secret of fudge is that it forms crystals, which help it gives it firm texture. But care in preparation keep the crystals very very small, ensuring that the texture feels smooth too. There’s dozens of delicious fudge recipes on the internet – make some to share with friends and family!
5 – DIY Marshmallows
Made yourself, marshmallows are AMAZING – and the extra flavours you can give to them are truly endless (we highly recommend raspberry marshmallows, they’ll blow your mind). The candy-making process involved in marshmallows is to help stabilize a foam produced by beating egg whites. Scientific American has some really neat facts about marshmallows in addition to some extra science experiments you can do with them, but if you’re just looking for an easy recipe that you can have fun with flavourings, check out Epicurious.
In addition to having the best topping for hot chocolate ever, you can enjoy a bonus chemical reaction called the Maillard Reaction by toasting the marshmallow over a stovetop or a firepit.
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