A MULTIPLE-VARIABLE APPROACH TO STUDY CORN-OIL OXIDATION

The induction time for oxidation (GAMMA(i)) and the rate constant for bimolecular peroxide decomposition (k2) were determined in refined corn oil with (CW) and without (CWO) antioxidant (ter-butil hydroxy-quinolein 0.0014%, citric acid 0.0012%), and their magnitude and variability were described through multiple regression. GAMMA(i) in both CW and CWO was mainly described (R2 > 0.93) through linear and quadratic interactions between the temperature (T-degrees) and the initial peroxide concentration. Although the antioxidant increased GAMMA(i), carbonyls were produced in earlier stages (i.e., <GAMMA(i)) and lower T-degrees than in CWO. These carbonyls were produced through a bimolecular peroxide decomposition. The equations for k2 (R2 > 0.96) indicated a faster decomposition of peroxide in CWO than in CW; nevertheless, as a function of T-degrees, k2 increased at a slower rate in CWO than in CW.