Volatile aldehyde emissions from heated cooking oils

Low molecular weight aldehydes (LMWAs) formed during the heating of frying media (triglycerides) were adsorbed onto tenax and analyzed by GCMS after thermal desorption. Six alkanals (C5 to C10), seven 2-alkenals (C5 to C11) and 3 alkadienals (C7, C9 and C10) were found in the fumes of canola oil (control), extra virgin olive oil, and refined olive oil, heated at 180 and 240 °C. The emission rates of these aldehydes depended on the heating temperature. Frying in any type of olive oil, independently of its commercial category, will effectively decrease the emission of volatile aldehydes at temperatures below the smoking point. Thus, using the cheaper olive oil for deep-frying purposes will not affect aldehyde emissions. This is important since olive oil is usually used for deep-frying operations while extra virgin olive oil is used as salad dressing in Spain. The mixture of refined olive oil with some virgin olive oil is the most acceptable type of olive oil in non-Mediterranean countries due to its milder flavor. However, if higher temperatures are needed the use of canola oil is more advisable due to its higher smoke point.