On-line LC-NMR-MS characterization of sesame oil extracts and assessment of their antioxidant activity

Sesame lignans were isolated by solvent extraction and subsequently purified by solvent crystallization from crude, unroasted sesame oil, and a sesame oil deodorizer distillate. In addition, an aliquot of the purified sesame oil extract was treated with camphorsulfonic acid to obtain a sesaminol-enriched extract. The sesame lignan composition of the extracts was characterized by on-line liquid chromatography nuclear magnetic resonance spectroscopy mass spectrometry coupling (LC-NMR-MS). The effect of the sesame oil extracts as well as pure sesame lignans and γ-tocopherol on the oxidative stability of sunflower oil (lignan-free) was studied by the Rancimat assay. The Rancimat assay revealed the following oxidative stability order: sesame oil extract < sesame oil deodorizer distillate < sunflower oil (no added sesame oil extracts) < sesamol < sesaminol-enriched sesame oil extract. In addition, the radical-scavenging capacity of these extracts was assessed by the Trolox® equivalent antioxidant capacity (TEAC) assay. The TEAC assay revealed a slightly different AOX activity order: sesamin < sesame oil extract < sesaminol-enriched sesame oil extract < sesamol. In conclusion, the sesaminol-enriched extract revealed strong antioxidant activity and is therefore suitable to increase the oxidative stability of edible oils high in polyunsaturated fatty acids.