Formation of Toxic Glyoxal, Methylglyoxal, and Diacetyl Formed in the Headspace of Heated Edible Oils

Toxic -dicarbonyl compounds, glyoxal (GL), methylglyoxal (MG), and diacetyl (DA), that formed in the headspace of 50 mL of seven different edible oils heated under simulated cooking conditions, were analyzed. Among the seven edible oils, canola oil generally yielded the highest levels of the three -dicarbonyl compounds, whereas safflower oil produced the lowest levels. In general, GL was formed from oil samples at the highest levels, ranging from 339 g (canola) to 19.7 g (safflower), followed by MG and DA. GL formed in olive and vegetable oils was significantly greater at 200 °C than at 150 °C. The total amounts of -dicarbonyl compounds recovered ranged from 725 g (olive oil at 250 °C for 1 h) to 46.3 g (safflower oil at 150 °C for 0.5 h). The results suggest that these toxic -dicarbonyl compounds escape into the ambient air during the cooking of lipid-rich foods, and that people are exposed to them.