Oxidative stability of extracted sesame oil from raw and processed seeds

Sesame oil was prepared from raw and processed seeds. Processing conditions were roasting at 200C for 20 min, steaming at 100C for 20 min, roasting at 200C for 15 min + steaming for 7 min and microwaving at 2450 MHz for 15 min. Oxidative stability of the resultant hexane-extracted oils was determined during storage under Schaal oven test conditions at 65C far up to 35 days. Methods employed included determination of fatty acid composition, iodine value (IV), peroxide value (PV), conjugated dienes (CD), para-ansidine value (p-AV) and 2-thiobarbituric acid (TBA) value. The oils from raw and roasted-steamed seeds had better oxidative stability than other processed oils. In addition, nuclear magnetic resonance (NMR) spectroscopy was used to evaluate the extent of oxidation of sesame oils by measuring the relative changes of aliphatic to olefinic (R(ao)) and aliphatic to diallylmethylene (R(ad)) protons of the oils. A gradual increase in the (R(ao)) and (R(ad)) values was observed during the entire storage period.