Oxidative Stability of Conjugated Linoleic Acid Rich Soy Oil

This study was conducted to determine the oxidative stability of conjugated linoleic acid rich soy oil (CLARSO) and the effects of conjugated linoleic acid (CLA) levels on volatile oxidation products formed during CLARSO oxidation. CLARSO oxidative stability was determined by gravimetric analysis, peroxide value, headspace oxygen analysis and p-anisidine value. Volatile oxidation compounds were analyzed by solid phase microextraction-gas chromatography with a flame ionization detector and a mass spectrometer. CLA oxidation results were highly dependent on analytical methods used and oxidation parameters measured. The gravimetric study showed a CLA concentration effect on oxidation, which was not seen in the headspace oxygen depletion and peroxide value. Volatile oxidation data indicate that CLARSO had significantly higher (p < 0.05) levels of pentanal and trans-2-heptenal than the other oils, but there was no significant difference between the amounts of any volatiles present in 8 and 15% CLARSO. This suggests that oxidation was greater in CLARSO and that CLA concentration did not affect oxidation.