BLENDING OF ROASTED AND UNROASTED SESAME SEEDS OILS WITH SUNFLOWER AND OLIVE OILS FOR IMPROVING THEIR ANTIOXIDATION POTENCY

Oils extracted from sesame seeds (roasted and unroasted), sunflower seeds as well as virgin olive oil (cold press) were evaluated for their oil contents, unsaponifiable percentage, iodine and saponifiction values. GLC analysis of fatty acids composition and sterols components were evaluated. In addition, lignans and tocopherols were identified by TLC. The extracted oils from roasted and unroasted sesame seeds were characterized by higher percentages of unsaponifiables (1.9 and 1.6% respectively) compared to sunflower oil (0.3%).Total sterols of roasted and unroasted sesame seeds (450.0 and 440.0 mg/100g of oil) were higher than sunflower and olive oils (370.0 and 260.0 mg/100g of oil respectively). Oils extracted from   sesame seeds (roasted at 180ºC for 30 min) and unroasted seeds were blended with sunflower and olive oils at two levels (5 and 10 %) for raising the antioxidation potency of these oil blends. The mixed oils were subjected to accelerated oxidation through heating in electric oven at 63ºC for different periods (2, 4, 6, 8, 10, 12 and 14 days). Peroxide values (PV, primary oxidation products) were followed during course of heating. From plotted curves (PV versus time) the induction period (IP) was calculated by determining the break point of the plotted curves (intersection point of the extraplotted parts of the curve). It was found that sesame oil contained powerful antioxidants (lignans), as determined by TLC, and when mixed with individual sunflower and olive oils generally, the antioxidative stability of oil mixtures was increased. Generally, the oil extracted from roasted sesame seeds was considered much more antioxidative than unroasted sesame seeds.