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| Thermal oxidation characteristics of main fatty acids in vegetable oils at high temperature by GC method |
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| KeyWord:characteristic fatty acid thermal oxidation kinetics oxidative stability |
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| Abstract: |
| The oxidation degradation curves of palmitic acid, oleic acid, linoleic acid and linolenic acid at different temperatures were determined by self-made high-temperature thermal oxidation apparatus and gas chromatography (GC). The parameters of thermal oxidation degradation reaction equation were calculated by differential method，including oxidative activation energy Ea, reaction order number n, reaction rate constant k and pre-factor A. The macroscopic reaction kinetics equations reflecting the thermal oxidation degradation of palmitic acid, oleic acid, linoleic acid and linolenic acid at high temperatures were determined. The results showed that the oxidation degradation kinetics models for different fatty acids were obtained as follows: palmitic acid, rA=-dcA/dt=9.292×1066exp(-648.492/RT)c6.504A; oleic acid, rA=-dcA/dt=3.213×1059exp(-548.724/RT)c5.201A; linoleic acid, rA=-dcA/dt=2865×1057exp(-515.468/RT)c3.220A; linolenic acid, rA=-dcA/dt=4.451×1039exp(-350.851/RT)c2.108A. The kinetics equations revealed the relationship between the oxidation reaction rate and the temperature (T) and substrate concentration (cA),and revealed the thermal oxidation characteristics of different fatty acids: as the unsaturation degree increasing, the thermal oxidation stability of fatty acids decreased, the higher of the unsaturation degree, the less of substrate concentration influenced on the thermal oxidation fatty acid, the greater of temperature influenced on the reaction rate. |
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