Comparison of microwave irradiation and conventional thermal heating on volatile profiles and degree of oxidation in corn oil

Volatile profiles and degree of oxidation in corn oils after microwave treatment for 50 min were compared to oils with conventional heating at 180 degrees C for 4 h. Oil microwaved for 10 and 50 min showed a similar degree of oxidation compared to the oil heated at 180 degrees C for 1 and 3 h, respectively, based on the primary and secondary oxidation products. However, the total volatile contents of 50 min-microwaved oil were significantly lower than that of corn oil heated for 1 h at 180 degrees C (P < 0.05). Microwave treatment accelerated the rates of lipid oxidation by 4.6 times compared to 180 degrees C thermal oxidation. Relatively short treatment with microwave irradiation may not provide sufficient time to generate volatiles from oil. Microwaved corn oil for 50 min had higher contents of hexanal and t-2-heptenal and lower contents of 2,4-decadienal and nonanal than the oils heated at 180 degrees C for 3 h. Reactive oxygen species may be involved in volatile formation in microwave-irradiated oils.

Automated summary

Microwave treatment and conventional heating have different effects on the degree of oxidation and volatile profiles in corn oils. Microwave treatment may accelerate the rate of lipid oxidation, but generate fewer volatile compounds.