Ability of iron to promote surfactant peroxide decomposition and oxidize alpha-tocopherol

Peroxides are an important factor in oxidative reactions in foods because t heir decomposition can result in formation of highly reactive free radicals . Emulsifiers such as the Brijs, Tweens, and lecithin were found to contain 4-35 mu mol of peroxides/g of surfactant. Peroxide concentrations in Tween 20 micelles increased in the presence of low iron concentrations but decre ased when iron concentrations were high, suggesting that iron was capable o f promoting both peroxide formation and decomposition. Oxidation of alpha-t ocopherol was observed in micelles high in peroxides (Tween 20) but not in micelles where peroxide concentrations were low (Brij). Transition metals a ccelerated the oxidation of alpha-tocopherol in Tween 20 micelles, whereas EDTA stabilized alpha-tocopherol in the presence of added Fe2+. These resul ts suggest that surfactant peroxides could decrease the oxidative stability of food emulsions by acting as a source of free radicals, especially in th e presence of transition metals.