| Conjugated linoleic acid (CLA) has multiple health benefits but it is difficult to obtain sufficient CLA in a healthy diet to obtain the clinical effects. A CLA rich-soy oil (CLARSO) with up to 20% CLA has been produced by heterogenous catalysis but no studies of its oxidative stability have been reported. CLARSO and soy oil primary and secondary oxidation products were measured at 50°C in the dark. The CLARSO was less stable than soy oil but adsorption bleaching improved its oxidative stability. However, induction times were dependent on the analytical method used. Fatty acid oxidation kinetics was determined by measuring each fatty acid and total hydroperoxides in CLARSO at 52 °C, 61 °C and 69 °C in the dark and determining unsaturated fatty acids oxidation rate constants, activation energies and frequency factors by the Arrhenius equation. CLA isomers had higher rate constants, higher activation energies and higher frequency factors than linoleic acid suggesting that CLA isomers had more collisions with oxygen than did linoleic acid. CLARSO TAG were first identified by analytical HPLC. Semi-preparative HPLC was then used to obtain CLARSO TAG fractions and determine fatty acid composition by GC-FID FAME analysis. Then CLARSO was evaluated by incubating 2g samples at 50 °C over 3 days. CLARSO TAG fractions were then isolated and changes in fatty acid content of each fraction determined. It was found that the stability linoleic acid in each fraction was directly related to linolenic acid content and decline, but independent of CLA content and decline, although decline of CLA was similar to that of linolenic acid. |
