The Science of Candy: Sugar Chemistry
According to the National Confectioners Association, 80 percent of people plan to share chocolate and candy with their loved ones during Valentine’s Day. Chocolate and conversation hearts are just some of the candies and confections shared during this holiday.
The primary ingredient in most candies is sugar. Sugar is a general term used to describe a class of molecules that includes sucrose, as well as fructose and glucose.
The first step to making most candies is typically to dissolve sugar into boiling water. This forms a sugar syrup that can be cooled by removing it from the burner. However, the way the syrup is cooled determines the type of candy produced. For example, rock candy is made by allowing the sugar syrup to cool over several days, while fudge requires continuous stirring of the cooling syrup so that the sugar crystals that form remain small.
The two main categories of candy, crystalline and non-crystalline, result from the arrangement of sucrose molecules in the candy.
Crystalline candy, such as fudge and fondant, normally has a lower sugar concentration than non-crystalline candy and may contain small fine crystals of sucrose.
Fudge is made by heating sugar and water to a temperature above the boiling point for water, which is 212° Fahrenheit. The candy maker pours the syrup into a pan so it can cool faster; this technique helps prevent sucrose molecules from forming into a large crystal. Once cooled to 122° F, the syrup is stirred and scraped, forming many crystals at once. Continued stirring helps the sucrose molecules spread among and bind to the crystal seeds. This helps keep the size of the crystals small and creates the fudge’s milky texture.
Glass candy, cotton candy and gummies are examples of non-crystalline candy, which generally has a higher sugar concentration than crystalline candy.
To make glass candy, sugar syrup is cooled rapidly to prevent crystals from forming. The dissolved sucrose molecules bind with one another, which causes the candy to become amorphous and take on the appearance of glass.
Fun fact: glass candy was historically used for stunts that involved people breaking windows. Gummies are made in a similar way to glass candy, but with gelatin added to the sugar syrup to give it a rubbery consistency.
While sugar is typically the primary ingredient in candy, many candies also include preservatives and other ingredients to keep treats sweet and edible. For example, the University of Hawaii’s Food Safety and Technology newsletter article, Common Food Additives in Candy, identifies several candy additives, including the following:
· Butylated hydroxyanisole (BHA) – An antioxidant that prevents fats and oils from becoming rancid in candies such as peanut-butter cups.
· Gum base – One of the main ingredients in chewing gum, it’s made by blending and heating several vegetable or synthetic fibers with a softener such as paraffin and antioxidants.
· Potassium sorbate – A preservative that is the potassium salt of sorbic acid, which is also a preservative.
Other common ingredients in candy can include caffeine, ascorbic acid and citric acid, which gives candies like lemon drops their tart flavor.