Changes in oxidation-derived off-flavor compounds of roasted sesame oil during accelerated storage in the dark

Oil oxidation and off-flavor compounds were evaluated in roasted sesame oil during accelerated storage at 70 °C in the dark for 4 weeks. Oil oxidation was monitored by measuring contents of conjugated dienoic acid (CDA) and polar compounds as well as by analyzing fatty acid composition by gas chromatography (GC). Off-flavor compounds were evaluated with the headspace gas analysis using a solid phase microextraction (SPME) and GC. The roasted sesame oil showed little change in fatty acid composition during storage, and contents of CDA and polar compounds increased slowly. Among off-flavor compounds including pentane, hexane, hexanal, heptanal, 1-pentanol, acetic acid, and furfuryl alcohol, hexanal, heptanal, or 1-pentanol content increased with storage time and showed a high correlation with CDA values of the oil. Acetic acid and furfuryl alcohol did not show consistent trends throughout the 4 week storage. The results confirmed high oxidative stability of roasted sesame oil and suggested use of hexanal, heptanal, or 1-pentanol as an indicator off-flavor compound to monitor the autoxidation of roasted sesame oil.