Temperature dependence of HNE formation in vegetable oils and butter oil

The temperature dependence of the formation of toxic 4-hydroxy-2-trans-nonenal (HNE) was investigated in high and low linoleic acid (LA) containing oils such as corn, soybean and butter oils. These oils contain about 60, 54 and 3-4% of LA for corn, soybean and butter oils, respectively. The oils were heated for 0, 0.5, 1, 2, and 3 h at 190 degrees C and for 0, 5, 15 and 30 min at 218 degrees C. HNE concentrations in the oils were analyzed by high performance liquid chromatography (HPLC). The maximum HNE concentrations in heated (190 degrees C) corn, soybean and butter oils were 5.46, 3.73 and 1.85 mu g HNE/g oil, respectively. The concentration of HNE at 218 degrees C increased continuously for all the three oils, although they were heated for much shorter periods compared to the lower temperature of heating (190 degrees C). HNE concentration at 30 min reached the maximum of 15.48, 10.72 and 6.71 mu g HNE/g oil for corn, soybean and butter oils, respectively. HNE concentration at higher temperature (218 degrees C) was 4.9, 3.7, and 8.7 times higher than at the lower temperature (190 degrees C) and 30 min of heating for corn, soybean and butter oils, respectively. It was found that HNE formation was temperature dependant in the tested oils.