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

Jukka-Pekka Suomela,Heikki Kallio,Marko Tarvainen

doi:10.1051/ocl/2017015

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.

Highlights

Fat oxidation, resulting in the formation of various primary and secondary oxidation products, takes place in dietary oils during prolonged storage and heating
It is noteworthy that air circulation in microwave oven was weaker compared with convection oven
The oil heated in microwave oven was stirred more frequently because its temperature was measured in both the beginning and the end of the 5 min period when the microwave oven was set off (Fig. 1)

Summary

Introduction

Fat oxidation, resulting in the formation of various primary and secondary oxidation products, takes place in dietary oils during prolonged storage and heating. Comparisons of the effects of microwave vs “conventional” heating of dietary oils on lipid oxidation and on the formation of lipid oxidation products have been scarce. A few comparative studies have been performed using sunflower oil, high oleic sunflower oil, virgin olive oil, olive oil and lard (Albi et al, 1997), refined cottonseed oil and hydrogenated palm oil (Farag et al, 1991) as well as cocoa fat (Krysiak, 2011). In all these studies, microwave heating appeared to modify the fats more even if the temperature of the

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Conclusion