CRUNCHY BEARS: Gummy bears become puffy and crunchy after expanding in a vacuum chamber.

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STANDARDS

NGSS: Core Idea: LS3.B, LS3.A, PS3.A

CCSS: LS.4

Standards

Crunchy Candies

Freeze-dried candy is popping up everywhere. Find out how these puffed-up sweets are made.

AS YOU READ, THINK ABOUT how temperature and pressure can transform foods.

EVAN-AMOS VIA WIKIMEDIA COMMONS

THE ORIGINAL FREEZE-DRIED SWEET

Food for astronauts is often freeze- dried to make it lighter and easier to transport. In 1973, NASA started selling freeze-dried ice cream so the public could try astronaut food. It is still sold at museums—although astronauts have never actually taken it to space.

When you bite into a gummy bear, you expect it to be chewy and soft. But imagine chomping down on one of these sweets and—CRUNCH! It crumbles into a tangy powder. That’s what happens when you eat freeze-dried candy!

A few years ago, freeze-dried candy exploded in popularity on YouTube and TikTok. People experimented by putting different candies in a freeze dryer—a machine used to remove moisture from food. In some cases, this would create “a puffed-up, crunchy version of the original candy, with a more intense flavor,” says Richard Hartel, a professor of food engineering at the University of Wisconsin, Madison. Candy companies caught on to this trend. Now freeze-dried sweets are available at most grocery stores.

Bite into a gummy bear. You expect it to be chewy and soft. But imagine chomping one of these sweets and—CRUNCH! It crumbles into a tangy powder. That happens when you eat freeze-dried candy!

A few years ago, freeze-dried candy became extremely popular on YouTube and TikTok. People experimented with different candies. They put them in a freeze dryer. This machine removes moisture from food. In some cases, this would create “a puffed-up, crunchy version of the original candy, with a more intense flavor,” says Richard Hartel. He’s a professor of food engineering at the University of Wisconsin, Madison. Candy companies picked up on this trend. Now most grocery stores carry freeze-dried sweets.

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FOOD PRESERVATION

Freeze-drying is used to preserve things like meats, fruits, and vegetables—fresh foods that contain a lot of water. Freeze-dried foods can go long periods without spoiling because removing water prevents bacteria and mold from growing.

Freeze-dryers normally remove water from food by freezing it and turning the solid ice directly into gas. But candies contain very little water. Their transformation occurs when exposed to a vacuum. After all the air is sucked out of the machine’s main chamber, any air trapped inside the candy will start to expand. If the candy is malleable enough, the escaping air will cause it to puff up. Sweets that contain very little air, like Nerds or rock candy, won’t change shape. Gummy candies expand until they resemble cheese puffs. Chewy candies, like Skittles, caramels, and taffy, inflate into light, crispy balls. Sweet!

Freeze-dryers normally remove water from food. First they freeze it. Then they turn the solid ice directly into gas. But candies contain very little water. They change when exposed to a vacuum. All the air is sucked out of the machine’s main chamber. Then any air inside the candy will start to expand. If the candy is malleable enough, the escaping air will puff it up. Some sweets contain very little air, like Nerds or rock candy. They won’t change shape. Gummy candies expand to look like cheese puffs. Some candies are chewy, like Skittles, caramels, and taffy. They inflate into light, crispy balls. Sweet! 

ARGUING FROM EVIDENCE: What food or candy would you want to put in a freeze dryer? Do you think it will puff? Why or why not?

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