With Halloween just around the corner, store shelves are full of a variety of candies to satsify every sweet tooth. If you've ever wondered how your certain candies make your tongue burn or lips pucker, read on for the science behind some of your favorite sweets.

What makes Atomic Fireballs so hot?

This classic candy, which was released in 1954 and aptly named during the Cold War, packs a double whammy when it comes to spice.

First, it contains cinnamaldehyde, the oil that gives cinnamon its taste. Cinnamaldehyde affects a protein in your mouth called TRPA1 that senses irritants.

But Atomic Fireballs also contain capsaicin, the compound that makes hot peppers spicy. The burning sensation you feel when eating the candy is caused by capsaicin binding with a protein called TRPV1.

TRPV1’s primary purpose is to detect body temperature, and when it’s activated, it sends a signal to your brain that your mouth is too hot.

Although your tongue might feel like it’s melting, eating hot candy like Atomic Fireballs doesn’t actually cause any tissue damage. However, frequent exposure to spicy foods can decrease TRPV1 activity and desensitize you to it.

The spice content of foods that contain capsaicin are measured on the Scoville scale in Scoville heat units.

At the low end of the spectrum are foods like bell peppers which score about a zero. Jalapenos are in the 3,500-8,000 Scoville heat unit range while industrial pepper spray can score in the 5 million range.

Atomic Fireballs are a 3,500 on the Scoville scale.

WarheadsWhat makes Warheads so sour?

These candies are so sour that some people have reported being unable to distinguish among the different flavors.

Warheads’ sourness comes from the malic, citric and ascorbic acids they contain, but malic acid is the main culprit behind the strong flavor.

The acid was first isolated in 1785 by Carl Wilhelm Scheele from apple juice. It’s responsible for the sourness of green apples, and it also provides a tart taste to wine.

Eating too many of the sour candies can cause irritation on the tongue, which prompted the candy manufacturer to include the following warning on wrappers: Consuming large quantities within a brief period may cause temporary irritation to sensitive tongues. Avoid contact with eyes.

Pop RocksWhat makes Pop Rocks pop?

Hard candy is made from sugar, corn syrup, water and flavoring, and the ingredients are mixed together and then boiled to drive off the water. Candy makers let the temperature rise, and what they’re left with is pure sugar syrup. When the mixture cools, it’s hardened candy.

However, when making Pop Rocks, the hot sugar blend is mixed with carbon dioxide gas at around 600 pounds per square inch. The gas forms tiny bubbles in the candy.

Once the candy has cooled, the pressure is released, which shatters the candy, but the pieces still contain the bubbles.

When you place the candy in your mouth, it melts just like regular hard candy, but this releases the bubbles. When you eat Pop Rocks, the pops you hear and feel is the carbon dioxide gas being released form those tiny bubbles.

This candy-making process is even patented.

Wint-O-Green LIfe SaversWhat makes Wint-O-Green Life Savers spark?

All hard candies produce some degree of light when you bite into them, but the light is typically very faint. This effect is called triboluminescence, a phenomenon in which light is generated through the breaking of chemical bonds when a material is ripped or torn.

Triboluminescence occurs when molecules — such as molecules in the sugar of Life Savers — force electrons out of their atomic fields. The freed electrons smash into nitrogen molecules in the air, and during this collision, the electrons impart energy to the nitrogen, causing them to vibrate.

The nitrogen molecules get rid of their excess energy by emitting light. It’s mostly ultraviolet light, which isn’t visible; however, they also produce a tiny amount of visible light.

The blue spark of a Wint-O-Green Life saver is brighter than most hard candies because of its wintergreen flavoring, or methyl salicylate. Methyl salicylate is fluorescent, meaning it absorbs light of a shorter wavelength and emits it as light of a longer wavelength.

Ultraviolet light has a shorter wavelength than visible light, so when you bite into the Life Saver, the methyl salicylate absorbs the ultraviolet light produced by the nitrogen. It then re-emits it as visible blue light.

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