Oxidation of Olive Oils during Microwave and Conventional Heating for Fast Food Preparation

The oxidation stability of extra virgin and refined olive oils produced in different countries were studied under different conditions of microwave heating (microwave oven Electrolux, 2450 MHz, 500 W) and conventional heating (200°C). Oils were heated in a microwave oven and in a conventional oven for 0, 3, 6, 9, 12, 15, 20, 25, and 30 minutes. The evaluated parameters were peroxide value, content of conjugated dienes, conjugated trienes (determined by absorbance at 233 nm and 274 nm, respectively), and fatty acid composition by GC. During microwave and conventional heating peroxide values and contents of dienoic compounds differed significantly between control and the heated samples. The microwave treatment did not produce significantly greater amount of oxidation products than traditional heating.