In the present stud changes of some chemical and physical properties of a soybean oil,. aerated at 120 ㎖/min through a porous gas distributor and cxidized at 45°∼180℃, was investigated. The results of the study were as follows:
The peroxide, thiobarbituric acid, and iodine value of the soybean oil which was aerated at 120 ㎖/min increased rapidly as oxidation temperature exceeded over 80℃. The acid value of the oil increased very rapidly as the oxidation temperature passed over 160℃.
The content of the unsaturated fatty acid of the oil decreased considerably as the oxidation temperature exceeded over 80℃, whereas that of the saturated fatty acid did not change appreciably. This related well to the changes of the iodine value of the oil subjected to the same experimental conditions.
The viscosity and refractive index of the oil increased rapidly as the oxidation temperature passed over 180℃. The following linear relationship hold for the viscosity and refractive index of the oil in the present study.
V=A exp(-E/RT)
where V=viscosity(poise), A=constant, E=activation energy for viscous flow,
R=gas constant, T=oxidation temperature(。K).
The following relationship also hold for the viscosity and refractive index(n^(20)-D) of the oil at the present experimental conditions.
n^(20)-D=1.4614+7.333×10-^st-2.9612×10^(-3) In V
where t=temperature(。C) at which the viscosity was measured.
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