Evaluation of Oxidative Stability of Rapeseed Oils by Microwave Heating: Compared with Conduction Heating

Abstract

To evaluate the microwave energy effects and the oxidative degradation of oils subjected to microwave heating (MH), thirty-three different rapeseed oil samples were treated with MH and conventional heating (CH) at the same heating curve. The oxidation indices showed that, comparing with CH, the rapeseed oil samples exhibited varying levels of oxidation degree under MH, which could be divided into three categories. The results of rapeseed oils bioactive components analysis indicated that there were strong negative correlations between microwave oxidation and contents of polyphenol, tocopherols, phytosterols and squalene. Moreover, the oxidation positively correlated with degree of unsaturation and water content, but did not relate to the contents of chlorophylls and β-carotene. PCA and HCA indicated that water, γ-tocopherol and polyphenol may be the main factors in microwave lipid oxidation. γ-tocopherol and polyphenol have antioxidant properties and what counts is the property was much higher in microwave than conventional heating. Overall, this study proved that some oils are suitable for microwave heating because of the oxidation resistance originated from bioactive components.

Keywords: rapeseed oil, Microwave heating, Oxidation, bioactive components