Formation of toxic alkylbenzenes in edible oils submitted to frying temperature: Influence of oil composition in main components and heating time

The influence of oil composition in the main components and of heating time at frying temperature on the formation of toxic alkylated monoaromatic hydrocarbons in oils is studied. Oils of very different compositions such as extra virgin olive, sunflower and virgin linseed oils were submitted to frying temperature in an industrial fryer for prolonged periods of time and the components of their headspace were periodically extracted by solid phase microextraction and studied by gas chromatography mass spectrometry; simultaneously, the formation of polar compounds was also monitored by means of dielectric constant measures. The results obtained evidence the formation of a very high number of alkylbenzenes with molecular weights ranging from 92 to 190. Evolution, during heating time, of the concentration of these compounds in the headspace of the three oils is reported for the first time. Taking these data into account, the ability of these oils to generate these kinds of compounds is evaluated. The formation of unsaturated alkylbenzenes in edible oils during heating at frying temperature is reported for the first time. Relationships between the nature and concentration of alkylbenzenes found and composition in the main components of the original oils are commented on. Significant increases in the concentrations of these toxic compounds in some of the oils studied, occurring before the oil reaches its permitted limit in polar compounds, suggests the advisability of analysing the safety of this limit, in order to protect public health.