Effects of microwave vs. convection oven heating on the formation of oxidation products in canola (Brassica rapa subsp. oleifera) oil

Abstract

Research on the effects of microwave vs. "conventional" heating of dietary oils on lipid oxidation has been very limited. In this study, canola oil (Brassica rapa subsp. oleifera) was heated in either convection or microwave oven to compare the effects of heating methods on triacylglycerol (TAG) oxidation. Peroxide and p-anisidine values (PV and p-AV, respectively) were determined and liquid chromatography-mass spectrometric (LC-MS) analysis of non-oxidized and oxidized TAG molecular species was performed. Neither of the heat treatments caused any considerable changes in PV of the oil samples. However, increase in p-AV was observed. The change was higher in the oil heated in microwave oven, demonstrating a higher increase in the amount of secondary oxidation products. The changes were accompanied by a decrease in the polyunsaturated TAG molecular species ACN:DB (acyl carbon number:number of double bonds) 54:7 and 54:6, this change also being higher in the oil heated in microwave oven.