Journal Article

Thermal oxidation kinetic of sesame oil (Sesamum indicum L.) by 1H NMR

Paulo Irajara Borba Carneiro, Fonseca, F. A, Schnitzler, E., Ponta Grossa State University. Ponta Grossa – PR – (Brazil.)

2012

Overview

This study aims to investigate by, 1H NMR the thermal oxidation kinetics of sesame oil (SO) and commercial sesame oil (CSO) obtained from roasted and unroasted seeds, respectively. The samples were heated at 180 deg C by 8 hours per day for 15 days. The 1H NMR data analysis indicated that the hydrogen concentration decreases during 96 h of heating, remaining at 69.51 percent, 60.63 percent and 42.69 percent of allylic (E), vinylic (V) and bis-allylic (G) hydrogen in SO, and 49.29 percent, 38.51 percent, 18.58 percent in CSO, respectively. Behaving as the first order oxidation kinetics, SO average rate constant (k = mol.L-1.h-1) was: kG = 0.088 more then kV = 0.0052 more then kE = 0.0037 and half-life period (h), t1 per 2(E) = 188.37 more then t1 per 2 (V) = 134.56 more the more then t1 per 2 (G) = 79.04. To CSO, kG = 0.0169 more then kV = 0.0101 more then kE = 0.0074 and t1 per 2(E) = 94.18 more then t1 per 2 (V) = 68.49 more then t1 per 2 (G) = 41.12. These results indicated that SO is more resistant to thermal oxidation [less then k, more then t1 per 2] than CSO [more then k, less then t1 per 2]. The study allowed to conclude that sesame oil obtained from unroasted samples has higher thermal-stability than commercial sesame oil from roasted seeds and that their cannot be used after 14.3 and 3.6 hours, respectively, for deep-frying purposes at 180 deg C.

• Subject: ENERGIA TERMAL / ENERGIE THERMIQUE / http://www.fao.org/aos/agrovoc#c_14216 / http://www.fao.org/aos/agrovoc#c_31905 / http://www.fao.org/aos/agrovoc#c_5472 / OXIDACION / OXIDATION / OXYDATION / SESAME / SESAMO / THERMAL ENERGY