| Affiliation: | (1) Department of Chemical and Biochemical Engineering, Toyama National College of Technology, 939-8630 Toyama, Japan;(2) Osaka Municipal Technical Research Institute, 536-8553 Osaka, Japan;(3) Rinoru Oil Mills Co., Ltd., 103-0027 Tokyo, Japan;(4) Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, 606-8502 Kyoto, Japan |
| Abstract: | The autoxidation processes of the cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) isomers of CLA were separately observed at ca. 0% RH and different temperatures. The t10,c12 CLA oxidized faster than the c9,t11 isomer at all tested temperatures. The first half of the oxidation process of t10,c12 CLA obeyed an autocatalytic-type rate expression, but the latter half followed first-order kinetics. On the other hand, the entire oxidation process of c9,t11 CLA could be expressed by the autocatalytic-type rate expression. The apparent activation energies and frequency factors for the autoxidation of the isomers were estimated from the rate constants obtained at various temperatures based on the Arrhenius equation. The apparent activation energies for the CLA isomers were greater than those for the nonconjugated n−6 and n−3 PUFA or their esters. However, the enthalpyentropy compensation held during the autoxidation of both the CLA and PUFA. This suggested that the autoxidation mechanisms for the CLA and PUFA were essentially the same. |
