Abstract: The migration of polycyclic aromatic hydrocarbons (PAHs) during the refining of crude soybean oil was investigated so as to prevent and control the risk of the presence of PAHs in foods containing soybean oil. For this purpose, we determined the contents of PAHs in phosphoric acid, caustic soda, activated clay used for degumming, deacidification, decolorization and deodorization of crude soybean oil and the corresponding processed samples as well as those in byproducts such as oil residue, soap stock, waste clay and deodorizer distillate. The results showed that PAHs were found in all refining agents and the benzo[a]pyrene (BaP) contents in phosphoric acid, caustic soda and activated clay were 0.95, 1.84 and 0.71 μg/kg, respectively. The total contents of 4 EU priority PAHs (benzo[a]anthracene, chrysene, benzo[b]fluoranthene and BaP) were 2.81, 16.81 and 8.85 μg/kg, and the total contents of 16 USEPA priority PAHs were 26.18, 112.61 and 111.85 μg/kg in the three agents, respectively. The removal rates of BaP during degumming, deacidification and deodorization were 7.57%, 23.57% and 91.65%, respectively. The removal rates of 4 EU priority PAHs during degumming, deacidification, decolorization and deodorization were 15.93%, 10.41%, 19.31% and 50.91%, respectively, and the removal rates of 16 USEPA priority PAHs were 15.45%, 11.59%, 6.66% and 52.99%, respectively. The contents of BaP in oil residue, soap stock, waste clay and deodorizer distillate were 0.45, 0.90, 0.52 and 12.49 μg/kg, respectively. The contents of 4 EU priority PAHs in these by-products were 10.14, 7.39, 9.69 and 300.50 μg/kg, respectively. The contents of 16 USEPA priority PAHs were 261.60, 434.49, 156.29 and 2 775.15 μg/kg, respectively.

Key words: soybean oil, PAHs, oil refining, refining agents, refining by-products, migration