Abstract: To understand the factors affecting persistent organic pollutants residue levels in yogurt, the concentrations of OCPs and PCBs in yogurt specimens from six production areas of northeast, center, southeast, south, southwest of Beijing and from different Chinese cities with same commercial brand were determined by GC-ECD combined with chemical separation methods. Meanwhile, the levels of OCPs and PCBs in yogurt and their raw milk samples were also analyzed. The results indicated that the concentrations of OCPs in yogurt from Beijing area were in the order of southwest >> south, center >> southeast, northeast, and PCBs in the order of center >> southwest > south, southeast >> sortheast. Also, both concentrations and compositions of OCPs and PCBs in same commercial brand yogurt samples produced in different regions significantly varied. This fact suggested that the environmental status of raw milk is a key factor to affect the pollutants residues in yogurt. Further, the levels of HCHs, DDTs and PCBs in yogurt were much lower than those in their raw milk, which is likely relevant to the manufacturing technology of yogurt, including heat treatments and microorganisms zymolysis during storage.

Key words: yogurt, organochlorinated pesticides (OCPs), polychlorinated biphenyls (PCBs), gas chromatograph equipped with electron capture detector (GC-ECD), influencing factors