Advance Journal of Food Science and Technology 6(1): 42-47, 2014 ISSN: 2042-4868; e-ISSN: 2042-4876 © Maxwell Scientific Organization, 2014 Submitted: August 12, 2013 Accepted: October 01, 2013 Published: January 10, 2014 Corresponding Author: Xingguo Wang, School of Food, Jiangnan University, Wuxi, 214122, P.R. China 42 Sources of Polycyclic Aromatic Hydrocarbons in Soybean Oil and its Dynamic Changes Refining Processing 1, 2 Ye Yu, 1 Qingzhe Jin, 2 Yue Wang, 3 Yan Gu and 1 Xingguo Wang 1 School of Food, Jiangnan University, Wuxi, 214122, P.R. China 2 Zhangjiagang Entry-exit Inspection and Quarantine Bureau, Zhangjiagang 215600, P.R. China 3 Eastocean Oils and Grains Industries (Zhangjigang) Co. Ltd., Zhangjiagang 215633, P.R. China Abstract: In order to understand the sources of Polycyclic Aromatic Hydrocarbons (PAHs) and the influence of the refining steps for soybean oils, soybeans, solvents and samples of the crude soybean oils and the corresponding neutralized, bleached and deodorized oil were collected online in a Chinese oil refinery and then analyzed for 12 different PAHs. PAHs are environmental carcinogenic compounds that may contaminate soybean oils due to contaminated soybeans and extraction solvents and their levels can be reduced by refining. The changes in PAH content in soybean oils at the various refining stages were investigated using a method based on HPLC with fluorescence detection. Soybeans, solvents and the crude soybean oils contained various amounts of PAHs. The PAH levels in the refined oils were considerably lower than those in the corresponding crude oils. An evident decrease in PAH content was observed during extraction, neutralization, bleaching and deodorization. Keywords: HPLC, Polycyclic Aromatic Hydrocarbons (PAHs), refined soybean oils, refining process INTRODUCTION Polycyclic Aromatic Hydrocarbons (PAHs) are a class of persistent organic pollutants that are carcinogenic, teratogenic and mutagenic (Bories, 1988; Larsen and Poulsen, 1987). The molecular structure of PAHs contains two or more fused aromatic rings. PAHs are ubiquitously present in the environment. Edible oils are daily necessities closely related to the lives of people. The following main routes of PAH contamination of edible oils have been proposed: • Oil crop contamination caused by industrial pollution during the cropping season (Bories, 1988; Lee et al., 1981) • Oil seed contamination in the drying process (Larsson et al., 1987; Dennis et al., 1991; Gertz and Kogelheide, 1994; Balenovic et al., 1995; Moret et al., 2000; Swetman et al., 1999) • Contamination in oil processing • Thermal polymerization of oils The European Union Commission Regulation No 1881/2006 has set a maximum level of 2 μg/kg for benzo [a] pyrene in oils and fats (excluding cocoa butter) intended for direct consumption or use an ingredient in foods (Commission, 2006). The German Society for Fat Science has set limits of 25 ppb for total PAHs and 5 ppb for the heavy fraction (Gertz and Kogelheide, 1994; Swetman et al., 1999; Speer et al., 1990). A maximum limit of 10 ppb for benzo (a) pyrene in edible oils has been established in food legislation in China (GB 2716-2005, 2005). Therefore, studies of PAHs in edible vegetable oils have attracted more attention. Currently, PAH levels in vegetable oils are mainly controlled by two methods: developing new technologies for oil extraction and refining crude oils from conventional extraction technologies. In order to control further PAH contamination of vegetable oils, researchers have begun to investigate the changes in PAH content of oils at different stages of processing (Larsson et al., 1987; Speer et al., 1990). Conventional refining process improvement is a focus of current research. The refining process removes harmful impurities in crude oils obtained from pressing or solvent extraction. Thus, the refined oils can meet national quality standards. Soybean oil is rich in the essential oil linoleic acid and the natural antioxidant vitamin E. It is one of the most widely consumed cooking oils in China. PAH residues in soybeans and solvents easily cause PAH contamination of soybean oil. Some authors have studied PAHs in soybean oil, but the sources of polycyclic aromatic hydrocarbons in soybean oil have not been studied. Soybean oil can be consumed after it has been refined. Larsson et al. (1987) studied PAHs and benzopyrene in crude and deodorized soybean oils using gas chromatography-mass spectrometry and found that PAHs and benzopyrene levels in deodorized soybean oil were reduced significantly. The refining
