Quality alteration of corn and rapeseed oils during microwave heating

In food systems, oxidation is one of the most significant processes. It has an impact on numerous interactions between food ingredients, producing both desired and undesired results. The aim of the study was to investigate the effects of microwave heating on the quality indicators of corn and rapeseed oils. Different exposure times were evaluated in order to replicate the typical times used in home microwave cooking: 0, 1, 3 and 5, respectively. After 5 minutes of microwave exposure, the peroxide index showed a significant increase for both types of oil (p ≤ 0.05). Corn oil was more unstable at heat treatment, producing higher amounts of hidroperoxides. Rapeseed fatty acids profile was rich in oleic (C18:1), vaccenic (C18:1i), linoleic (C18:2), palmitic (C16:0) and linolenic (C18:2) fatty acids, followed by miristic (C17:0) and stearic (C18:0) acids. Both oils' fatty acid profiles changed as a result of microwave heating, polyunsaturated fatty acids, which are more susceptible to oxidation due to their higher number of double bonds, were the most affected fraction. Microwave heating exerted more aggressive effects on corn oil, and rapeseed oil can be exposed for 5 minutes without negative effects.