Effects of roasting conditions of sesame seeds on the oxidative stability of pressed oil during thermal oxidation

Oxidative stability of sesame oil (SO) prepared from sesame seeds roasted at 213, 230, and 247 °C for each 14, 21, or 28 min was determined at 180 °C heating condition by 2,2-diphenyl-1-picrylhydrazyl (DPPH), conjugated dienoic acid (CDA) value, headspace oxygen analysis, and profile changes of sesamol and sesamolin. As sesame seeds were roasted with longer time and higher temperature, more sesamol was found in SO. SO from sesame seeds roasted at 247 °C for 28 min had the highest oxidative stability based on the results of CDA and headspace oxygen. Absorbance of DPPH from SO roasted at 230 and 247 °C showed different patterns compared to those from SO at 213 °C during thermal oxidation. Sesamol was continuously generated with the decrease of sesamolin in SO from 230 to 247 °C while sesamol in SO from 213 °C did not increase during 180 °C heating. Higher oxidative stability of SO may be related with the continuous generation of sesamol from the degradation of sesamolin during thermal oxidation rather than the initial antioxidant content.