Effects of conventional and microwave heating on the degradation of edible vegetable oils

A comparative study was performed to evaluate the effects that microwave (12 and 15 min at 1,100 W) and conventional heating (36 and 45 min at 230 degreesC) have on olive oil (refined+virgin). The extent of the oxidative and hydrolytic degradation of the differently heated oils was evaluated by high performance size-exclusion chromatographic analysis of their polar compounds. The experimental results showed a great degradation of the oils with values of polar compounds higher than 26% at the most intense treatment. Significantly higher amounts of polar compounds, of triglyceride oligopolymers - known to have adverse effects on human health - and of oxidised triglycerides were found in microwaved than in conventionally heated oils, indicating a higher extent of oxidative degradation