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How do BHA, BHT, and TBHQ slow rancidity in 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.

BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), and TBHQ (tertiary butylhydroquinone) slow the development of rancidity in foods by acting as free radical scavengers.12

Rancidity in fatty foods is primarily caused by the autoxidation of unsaturated fatty acids, a process that proceeds through a self-sustaining chain reaction. This reaction relies on highly reactive intermediate molecules known as free radicals, which contain unpaired electrons and propagate the breakdown of lipid molecules into compounds that produce off-flavors and off-odors.341

BHA, BHT, and TBHQ function by reacting with these free radical chain carriers, effectively terminating the oxidative chain reaction. They achieve this by donating hydrogen atoms to the radicals, which stabilizes them and prevents the cycle of degradation from continuing. By interrupting this process, these synthetic antioxidants delay the chemical deterioration of fats and oils, thereby preserving the quality and shelf life of various food products.142