Invented in 1954, Atomic FireBall candies are famous for their red-hot flavor. To achieve their fiery heat, candy makers use two ingredients designed to interact with your mouth in different ways.
First, the candy delivers an explosion of spice that comes from the chemical cinnamaldehyde, the oil that gives cinnamon its flavor. Cinnamaldehyde triggers taste receptors on your tongue that detect irritating compounds. Raw garlic and horseradish can set off the same receptors.
Behind the cinnamon flavor is a deeper heat. It comes from capsaicin, the compound that makes chili peppers spicy. An Atomic FireBall contains slightly more capsaicin than a jalapeño pepper. Capsaicin activates a protein, or large biological molecule, in your mouth that usually detects temperatures greater than 43°C (110°F) to alert you that something you’re eating is hot. When sucking on an Atomic FireBall triggers this protein, your body may react by sweating in an attempt to cool down, even though you’re not actually overheating.