The effect of temperature and heating time on the formation of alpha, beta unsaturated hydroxyaldehydes in various vegetable oils and fats

Abstract

The formation of HNE, HHE, HOE and HDE was investigated in commercial corn, soybean, peanut, canola oils, lard and beef tallow which were heat treated at different temperatures (145, 165 and 185°C) for 1, 3 and 5 hours. The formation of these 4–hydroxyaldehydes was monitored as 2, 4–dinitrophenylhydrazone derivatives by HPLC. These oils and fats were selected based on their different fatty acid distributions. In general, the formation of these 4–hydroxyaldehydes increased with higher temperatures (145, 165 and 185°C), longer heating time (in the range of 0 to 5 hours) and higher unsaturation in the samples. It was found that the formation of HNE was dependent on temperature, heating time and the level of linoleic acid in the oils. Therefore, to minimize the formation of the toxic HNE in high linoleic acid containing oils, the lowest temperature and the shortest heating time should be used.