Polycyclic aromatic hydrocarbons in crude and deodorized vegetable oils

The efficiency of the refining process in removing polycyclic aromatic hydrocarbons (PAH) from crude vegetable oils was studied. Samples of the crude oils (coconut, soybean and rapeseed oils) and the corresponding refined, deodorized oil were taken on-line in three Swedish oil refineries and margarine manufacturing plants and analyzed for 20 different PAHs. Of the crude oils, coconut oil had by far the highest PAH levels. However, the PAH levels in the refined coconut oils were very low. This shows that the activated charcoal treatment used for removing PAHs from coconut oil achieves the desired effect. The crude soybean and rapeseed oils contained relatively low, but varying, amounts of PAH. At present these oils are not purified by activated charcoal. Nevertheless, the PAH levels in the refined oils were considerably lower than those in the corresponding crude oils. This probably is due to evaporation of PAH in the deodorization process, where steam is passed through the hot oil under high vacuum. However, deodorization has only a marginal effect on the high molecular PAHs, of which several are classified as carcinogens.