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Keywords:

  • Antioxidant activity;
  • Bene hull oil;
  • Rice bran oil;
  • Sesame oil;
  • Sunflower oil;
  • Unsaponifiable matters

Abstract

Chemical composition of sesame (SEO), rice bran (RBO) and bene hull (BHO) oils was determined. During oven test, peroxide value on day 8 (PV8, meq/kg) and carbonyl value on day 6 (CV6, µmol/g) were considered as measures of resistance to the formation of primary and secondary oxidation products, respectively. The SEO and BHO showed statistically the same PV8 (381.4 and 359.8, respectively) and CV6 (25.2 and 25.8, respectively), and their stabilizing effect was significantly better than that of the RBO (455.5 and 32.7, respectively). The unsaponifiable matters (USM) fraction of the BHO (443.7 and 26.8, respectively) had an antioxidative effect higher than those of the SEO (478.0 and 38.6, respectively) and RBO (482.4 and 37.4, respectively). There was a good correlation (R2 = 0.972) between the PV8 and CV6 throughout oxidation period. On the basis of the oxidative stability index (OSI, h) of Rancimat test, the best carry-through properties belonged to the SEO (6.92 h), followed by the RBO (6.12 h) and BHO (5.0 h), and also a similar order was observed for the USM fractions (5.89, 5.28 and 4.50 h, respectively). There was no correlation between the results of Rancimat and oven tests, showing that the powerful antioxidative agents under oven test conditions were lack of appropriate carry-through properties. The highest significant reducing power (mmol/L) belonged to the SEO (258.1), followed by the RBO (218.7) and BHO (152.4), whereas the USM fraction of the SEO indicated the least significant quantity among the USM fractions (89.3 vs. 216.6 and 158.0 for the RBO and BHO, respectively).