Effect of alkyl chain length on the antioxidant activity of alkylresorcinol homologs in low-moisture crackers

Abstract

Alkylresorcinols (ARs) are a naturally occurring homologous series of phenolipids extracted from rye bran which have previously shown antioxidant activity in lipid-containing foods. This study extends previous work to consider their use in low-moisture foods using crackers as a model system. ARs (153 μmol) were capable of inhibiting lipid oxidation reactions based on the delayed generation of lipid hydroperoxides and headspace hexanal compared to a control treatment and were more effective than α-tocopherol which displayed prooxidant behavior. The antioxidant activity of ARs was observed to increase as a function of increasing alkyl chain length, with optimum activity at an alkyl chain length of C23:0; however, ARs were lost at a rate independent of alkyl chain length. A mixture of ARs displayed comparable antioxidant activity to the C23:0 and C25:0 homologs, all of which exerted stronger activity than butylated hydroxytoluene providing an effective alternative to synthetic antioxidants. These findings suggest that ARs are effective antioxidants in low-moisture foods likely because of their hydrophobicity, which allowed them to localize in the lipid phase, the purported site of lipid oxidation in the model cracker system.