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How do antioxidants called free-radical scavengers protect foods?

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A woman reads the nutrition labels on two brightly colored boxes of cereal. — food additive Labels provide information on a food product's ingredients and nutritional value.

Antioxidants known as free-radical scavengers protect foods by terminating the oxidative chain reaction that leads to rancidity in fats and oils.12

In many foods, autoxidation occurs when unsaturated fatty acids react with oxygen, creating highly reactive free radicals—molecular fragments with unpaired electrons. These radicals propagate a cycle of chemical degradation that produces volatile compounds responsible for off-flavors and off-odors.132

Free-radical scavengers, such as tocopherols, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT), interrupt this process by donating hydrogen atoms to the chain carriers. By reacting with these radicals, the antioxidants convert them into stable, nonpropagating products, thereby slowing the rate of oxidation and preserving the quality and shelf life of the food.123