Deterioration Kinetics of Crude Palm Oil, Canola Oil and Blend During Repeated Deep-Fat Frying

The oxidation of vegetable oils is generally treated as an apparent first order kinetic reaction. This study investigated the deterioration of crude palm oil (CPO), refined canola oil (RCO) and their blend (CPO:RCO 1:1 w/w) during 20 h of successive deep-fat frying at 170, 180 and 190 A degrees C. Kinetics of changes in oil quality indices, namely, free fatty acid (FFA), peroxide value (PV), anisidine value (p-AV), total polar compounds (TPC) and color index (CI) were monitored. The results showed that FFA and PV accumulation followed the kinetic first order model, while p-AV, TPC and CI followed the kinetic zero order model. The concentration and deterioration rate constants k, increased with increasing temperatures. This effect of temperature was modeled by the Arrhenius equation. The results showed that PV had the least activation energies E (a) (kJ/mol) values of 5.4 +/- 1 (RCO), 6.6 +/- 0.7 (CPO) and 11.4 +/- 1 (blend). The highest E (a) requirement was exhibited by FFA with a range of 31.7 +/- 3-76.5 +/- 7 kJ/mol for the three oils. The overall E (a) values showed that the stability of the blend was superior and not just intermediate of CPO and RCO. The correlation of the other oil quality indices with TPC indicated a positive linear correlation. The p-AV displayed the strongest correlation, with mean correlation coefficient r (s) of 0.998 +/- 0.00, 0.994 +/- 0.00 and 0.999 +/- 0.00 for CPO, RCO and blend, respectively.