Kinetic parameter determination of vegetable oil oxidation under Rancimat test conditions

摘要

In this research, five different vegetable oils were oxidized at four different temperatures (373, 383, 393, and 403 K) under Rancimat test conditions. An increasing rate of oxidation could be observed as temperature increased. The natural logarithms of the kinetic rate constant (k value) varied linearly with respect to temperature, with the temperature coefficients (T_(Coeff)) ranging from 6.95 x 10~(-2) to 7.40 x 10~(-2) K~(-1) for the vegetable oils. On the basis of the Arrhenius equation and the activated complex theory, frequency factors (A), activation energies (E_a), Q_(10) numbers, activation enthalpies (ΔH~(++)), and activation entropies (ΔS~(++)) for oxidative stability of the vegetable oils were calculated. The A, E_A, Q_(10), ΔH~(++), and ΔS~(++) values for the vegetable oils ranged from 6.38 x 10~3 to 28.03 x 10~3 h~(-1), from 86.86 to 92.42 kJ/mol, from 2.08 to 2.18, from 83.64 to 89.20 kj/mol, and from -116.66 to -104.35 J/mol K, respectively.