Abstract
Pan-frying with diacylglycerol-rich cooking oil (DG oil) was carried out to assess the influence of thermal cooking on the oxidative stability of DG oil in comparison with that of triacylglycerol-rich cooking oil (TG oil). The DG oil was spread over the surface of an aluminum pan coated with stainless steel, which was heated for a specified time with an IH electric heater. The color difference (ΔE value)of the DG oil after 120 seconds of heating at a temperature of more than 200°C was greater than that of the TG oil. The p-anisidin and carbonyl values, which were used as oxidative indices of the DG and TG oils, were not changed at a temperate of less than 200°C, but these values increased in proportion to the heating time at ahove 200°C. The acid value of the DG and TG oils did not change above or below 20O°C, while the peroxide value of both oils increased in proportion to the heating time below 200°C. The amounts of polyunsaturated fatty acids (C18: 2 and C18: 3) decreased markedly after 120 seconds of heating at above 200°C. These results indicate that the thermal oxidation of DG oil during pan-frying was basically the same as that of TG oil, and that both oils seemed to be stable during short-term heating at temperatures less than 200°C.
