How does popping candy work?

How does popping candy work?


If you’ve increased your consumption of popsicles in recent weeks (we certainly have in Cosmos), you may have tried some candy. It’s a treat and a science experiment all in one, causing a tingling sensation on the tongue and a delicious crunch as you eat it.

But what causes that popping feeling?

You might think it’s a chemical reaction, but it’s actually a cool combination of gases and heat. The precise recipes vary from brand to brand, but popped candies are usually a mixture of a few different types of sugar and small, pressurized bubbles of a gas, usually carbon dioxide. For this reason, in some patent applications it is also known as “carbonated candy”.

The gas is added to the melted sugar under high pressure, at least two to three times the typical air pressure at sea level, and sometimes much higher. With the right combination of temperature and pressure, sugar forms tiny crystals, each containing several gas bubbles about one-tenth to one-fifth of a millimeter in diameter.

Sugar dissolves in water, so when the candy comes into contact with the tongue, the water in the saliva breaks these bubbles. The pressurized gas escapes, sometimes with enough force to break the rest of the candy crystal. This is what causes the tingling and popping sensation.

Both bubbles and crystals are very small, so the amount of force involved in these cracks is unlikely to cause any problems. But as a bit of bad news, at least one lab study has found that popped candies can have an effect on tooth enamel.

If you want to see fizzy candy but are worried about your teeth, you can add it to plain water; this will also activate it.

This is particularly good news, because it means that popped candies can be used in chemical reactions. Last year, a group of Chinese and Australian chemists used candies to extract some key molecules from vinegar and two alcoholic beverages: beer and baijiu, a liquor made from fermented grains. This opens the way for a range of potential applications in food or pharmaceutical additive manufacturing.

The carbon dioxide released by the popped candy turned out to be the perfect way to stir the mixtures and disperse the relevant substances. And, because it uses edible sugars, the method is more environmentally conscious and leaves the safe-to-eat ingredients last.

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There are no stupid scientific questions, but sometimes the answers can be hard to find.

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