B.H. Chen


Polycyclic aromatic hydrocarbons (PAHs), formed through incomplete combustion or pyrolysis of wood or gasoline, represents an important class of toxicological compounds because of its wide distribution in the environment and possible contamination of foods. This paper deals with an overview of analysis, formation and inhibition of PAHs in foods. Extraction of PAHs from food is routinely conducted by saponification of lipid with Soxhlet method, followed by purification with a Sep-Pak Florisil cartridge and partition. This method can remove more impurities than the sonication method. With HPLC, all 16 PAHs can be simultaneously separated by a gradient solvent system and detected by UV at 254 nm or fluorescence employing programmable wavelength with seven settings of excitation/emission. With GC, all 16 PAHs can also be simultaneously separated by a temperature programming method and detected by flame ionization detector (FID) or ion-trap mass detector (ITD). Although HPLC can provide adequate separation of 16 PAHs, nevertheless, the presence of impurities in food sample can interfere with the subsequent identification and separation. For GC, a number of isomeric PAHs partially overlap. Nonetheless, the application of GC-ITD can readily identify the various PAHs in foods through reconstructed ion chromatograms even in the presence of fat- or PAH-like impurities. Charcoal-grilling and smoking are the two major processing methods which can result in the formation of high amount of total carcinogenic PAHs. No carcinogenic PAHs are detected in steaming and liquid smoke flavoring. The amount of PAHs in food samples can also be greatly reduced by sorption into low-density polyethylene bags. Further research in necessary to determine how the formation of PAHs during processing can be directly retarded or eliminated.