The Science of Glassy Hard Candy

Hard candy is not actually a solid crystal but a supercooled liquid that resembles glass. By heating sugar syrup to 320 degrees Fahrenheit, chefs create a stable, non-crystalline structure that stays brittle at room temperature.

When you bite into a piece of hard candy, you are crunching through an amorphous solid. Unlike chocolates which rely on precise fat crystals, hard candy is essentially sugar glass held in a disordered state. The lack of crystal structure is what gives these treats their signature transparency and sharp, glassy snap. Because of this unique chemistry, these sweets can last for years if kept away from humidity.