The effect of herb extracts on the off-odor formation from lipid oxidation

Abstract

Hexanal has been widely used as an index of oxidized odor. However, off-odor components have different threshold values, and the antioxidant mechanisms for lipid oxidation and off-odor formation might differ. This study investigated the antioxidative activity of herb extracts for inhibiting various off-odor components, including hexanal, derived from lipid oxidation. Linoleic acid emulsions to which each herbal extract (spearmint, German chamomile, echinacea or lemongrass) was added were subjected to an oxidation reaction at 37 °C for 5 h. Hydroperoxide was evaluated by the ferric thiocyanate method and the volatiles were analyzed by high-performance gas chromatography. As a result, spearmint (Perillaceae herbs) showed high antioxidant activity for lipid oxidation and off-odor formation. The catechol structure of rosmarinic acid, the main component of spearmint, contributed to its activities. Moreover, the degree of inhibiting off-odor formation differed depending on the precursor of the off-odor component or the antioxidants used.