The use of sesame oil unsaponifiable matter as a natural antioxidant

Individual components of sesame oil unsaponifiable matter isolated from two different coloured seed varieties (white and brown) were identified and quantified. Unsaponifiables from the brown sesame variety were markedly different in their composition from those of the white variety. The brown variety contained higher amounts of total sterols and tocopherols but lower amounts of sesamin, sesamolin and total hydrocarbons than the white variety. The seeds were roasted at 180 °C for 30 min. Roasting increased some effective antioxidant compounds. These included relatively higher percentages of sesamol, Δ24,28 ethylidene sterols (Δ5 and Δ7-avenasterols), squalene, as well as tocopherols and some active browning substances. These antioxidative components are effective via synergistic action. Additionally, unsaponifiable matter from unroasted (USM) and roasted white sesame seeds (RSM) was added individually to sunflower oil at levels of 0.02, 0.05 and 0.1% and their effectiveness was compared with a control (no additives) at 63 °C. Results indicated that both USM and RSM had antioxidant activity which increased with increasing concentration. Compared to USM, the RSM was a better antioxidant in most cases. Moreover, the addition of 0.1% RSM gave a strong antioxidative efficiency and this could be used as an alternative natural antioxidant for food applications.