Removal of polycyclic aromatic hydrocarbons by low density polyethylene from liquid model and roasted meat
Introduction
Polycyclic aromatic hydrocarbons (PAHs, also known as polycyclic organic matter or POM) are formed by the incomplete combustion of organic matter, in particular, from fossil fuels or when vegetation is burned. PAHs are ubiquitous environmental contaminants, and many have been found to be mutagenic and/or carcinogenic, as well as to have cardiovascular, bone marrow or liver toxicity (Collins, Brown, Alexeeff, & Salmon, 1998; IARC, 1983, IARC, 1987; Phillips, 1999; USEPA, 1987).
PAHs migrate through the food chain into hydrophobic compartments, and, thus, accumulate in lipid components due to their lipophilic nature (Chen & Chen, 2001; Madhaven & Naaidu, 1995; McLachlan, 1997; Roeder, Garber, & Schelling, 1998). The presence of PAHs in food is the predominant cause of human exposure to them. Food components, such as fats, cause PAHs to be generated through thermal degradation or thermal polymerization, and different thermal processes affect their production quantitatively (Chen, 1997; Phillips, 1999). GC-FID has been widely used for the determination of PAHs in food analysis, because the GC-FID response is the same for all PAH compounds and linear over a large concentration range (ca. 1–106) (Chen & Lin, 1997; Djozan & Assadi, 1999; Mottier, Parisod, & Turesky, 2000; Simko, 2002; Wu, Wong, Lee, Shi, & Ong, 1997).
PAHs are chemically inert and hydrophobic. Their carcinogenicity is initiated by their metabolic conversion in mammalian cells to diolepoxides that bind covalently to cellular macromolecules, including DNA, causing errors in DNA replication and mutation (Phillips & Grover, 1994). There is also evidence that other reactive intermediates are generated by a one-electron oxidation process that can result in the chemically unstable alkylation of DNA, leading to depurination (a potentially mutagenic event) (Rogan et al., 1993). Due to their carcinogenic activity, some European countries, such as Germany, have adopted a legal limit of 1 ppb for the benzo(a)pyrene (BaP) content in smoked foodstuff, 25 ppb for total PAHs and 5 ppb for the heavy fraction (Moret & Conte, 2000). Currently, a reduction in PAH levels in food products can be achieved by alternative processes which suppress the formation of PAHs (Chen & Lin, 1997), as well as remove PAHs by sorption to the packaging film (Simko & Brunckova, 1993; Simko, Simon, Khunova, Brunckova, & Drdak, 1994; Simko, Khunova, Simon, & Hruba, 1995; Simko, Simon, & Khunova, 1999; Van Lune, Nijssen, & Linssen, 1997). Although PAHs are stable, degradations through photolysis and microorganisms are the major ways to decompose them (Manahan, 1991; Miller, Singer, Rosen, & Bartha, 1988; Sabate, Bayona, & Solanas, 2001; Saftic, Fedorak, & Anderson, 1992). Previous study (Bernstein et al., 1999) also showed a conversion of PAHs to oxidative derivatives on exposure to UV radiation in ice.
The ability of plastic to adsorb some compounds in food represents an effective route to eliminate some hazardous components from foods. The aims of this study were to evaluate the use of LDPE in removing PAHs in liquid medium models, including aqueous, water–oil and water–oil containing phospholipid systems. Additionally, the procedure was applied to remove PAHs from roasted duck skin packaged in a LDPE pouch at ambient temperature. Subsequently, reduction of PAHs in PE materials by exposure to UV radiation was also investigated.
Section snippets
Chemicals
Sixteen PAH standards, including naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-c,d]pyrene were purchased from Accustandard Co. (New Haven, CT), and used to determine the retention time and peak area response by GC analysis. Five carcinogenic PAHs, including benzo[a]anthracene (BaA), benzo[b
Identification and quantification of PAHs by GC
Identification and quantification of the PAHs was achieved by gas chromatography modified from Wu et al. (1997). The 16 PAH standards were separated and identified under the GC conditions employed (Fig. 1(a)), and the selected PAHs adsorbed to the LDPE were also identified under the three liquid models (Fig. 1(b)–(d)).The limits of detection for the selected carcinogenic PAHs, including BaA, BbF, BaP, DBahA and IcdPy, were 0.10 ppm, and the R2 values of each standard PAH curve (concentration of
Conclusion
The results obtained in this study lead to the following conclusions. The sorption of PAHs to LDPE in liquid models was related to the mobility of chemical in the liquid, and most of the total adsorption occurred within 24 h. PAHs in roasted meat products may be removed by being in contact with the packaging film, and then eliminated by UV radiation. This approach of removal of PAH compounds from meat products is beneficial for eliminating these hazardous chemicals.
Acknowledgements
This research was financially supported by the National Science Council, Executive Yuan, Taiwan (NSC 90-2214-E-030-001).
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