Formation of plycyclic aromatic hydrocarbons in cooked meat and the possibility of reducing their formation by vitamin E

Polycyclic aromatic hydrocarbons (PAHs), known as potential human carcinogens, have received an increased attention in the recent year, due to their source diversity. Human exposure to PAHs occurs primarily through dietary intake. As diet contributes to 88–98% of exposure, this rising concern results reasonable and of great importance. PAHs generation in food and in particular in meat is due to high-temperature cooking methods such as grilling. The European Union has established PAH4 (sum of benz[a]anthracene, chrysene, benzo[b]fluoranthene and benzo[a]pyrene) as the most appropriate indicator for the occurrence and carcinogenic potency of PAHs in food. In the light of the emerging issue health risk from exposure to PAHs and in order to provide useful information on the PAHs contamination of meat, different control measures aimed in inhibiting or reducing PAHs formation have been attempted and discussed worldwide. Among them mitigation strategies consisting in the use of antioxidants has gain particular attention. The present study, therefore, aimed to study the effect of vitamin E, potent natural antioxidant, in the formation of PAHs in cooked meat. For this purpose, two trials were carried out: 1. Beef and chicken meat model systems: vitamin E was added to the ground meat prior cooking. The aim of these two trials was to investigate how PAHs formation respond to different concentrations of vitamin E added before meat grilling; 2. Animal model: vitamin E was intramuscularly injected to broiler chickens in order to study how endogenous tissues levels of vitamin E could affect PAHs formation. In the first two trials (beef and chicken model systems) different concentration of Vitamin E (dl -tocopheryl acetate) were added to beef and chicken burgers prior grilling. For each meat type, the experimental groups (n=2 burgers for each group) consisted in the control group (C) and groups added with dl -tocopheryl acetate: 2 μg/g (C1); 3 μg/g (C2); 4.5 μg/g (C3) and 6 μg/g (C4) respectively. Burgers of 80 g each were directly cooked in disposable barbecue obtaining well-done level of doneness. For the animal model trial, ten 43-d-old Ross 308 male chickens were divided into two equal weight groups. Each week, from the beginning of the study, 5 birds received intramuscular injections, in the left Pectoral muscle, of dltocopheryl acetate (50 mg/ mL) (Vitalene® E, Fatro, Bologna). The total doses for birds were as follows: 0 IU (Control group) and 100 IU (Group Vit E). Control group birds were given injections of physiological saline. Chicken burgers obtained from breast meat of control chickens (C, n =5) and vitamin E injected chickens (T, n =5) were prepared and grilled following the same conditions as in the first trial. An acetonitrile based-extraction and high-performance liquid chromatography with fluorescence detection were used to assay 14 PAHs in meat samples. Data of both trials were analysed by one-way ANOVA. The obtained results can be summarized as follows: Trial with beef meat model system: In relation to the total content of PAHs, no effect was observed in hamburgers added with 2 μg/g of vitamin E, while a significant reduction was found in those added with 3 and 4.5 μg/g compared to control samples. Higher vitamin levels reduced the formation of heavy and light PAHs. Benzo[a]pyrene (BaP) was detected only in beef burgers of control (0.06 ng/g) and in those added with 2 µg/g and 6 µg/g of vitamin E, while in other groups was below the LOQ (< 0.04 ng/g). Considering that several are the factors which can influence the formation of PAHs, such as the total lipid and fatty acid composition of meat, the same study was carried out on chicken meat, and the results are showed in the following trial. Trial with chicken meat model system: Raw chicken meat samples used presented an endogenous vitamin E content of 5.54 μg/g; total lipid content was 2.08 g/100g and the fatty acid profile was characterized by a higher proportion of MUFA (42.12%), followed by SFA (36.46%) and PUFA (21.42%). Regarding the effect of vitamin on PAHs formation in grilled chicken, all vitamin E added groups were characterized by a significant lower total PAHs content as compared to C group. The control group was characterized by the highest PAH4 content (4.54 ng/g), while the addition of vitamin E to chicken patties reduced significantly the total PAH4 amount at all the concentration used. In all burgers added with vitamin E was observed a highly significant reduction of BaP content. Animal model trial As expected, meat from vitamin E treated group had higher content of tocopherol (5-fold) compared with the control one (2.93 μg/g). Total lipid content was similar between groups. Regarding the fatty acid profile, comparison of the experimental groups revealed no differences in MUFA and PUFA content; while a lower SFA content was found in treated chickens compared to control group In grilled chicken, the concentrations of PAH4 were similar between groups (2.68 ng/g and 2.15 ng/g for control and vitamin E, respectively), values well below the maximum level of 30 ng/g established by the EU regulation. As well as, the concentration of BaP was similar between groups and lower (0.17 – 0.21 ng/g) than the maximum levels of 5 ng/g established by the EU regulation. Considering these preliminary results, further research is needed with a higher number of samples and with a wider range of doses of vitamin E and a different timeline to better understand the pharmacokinetics of vitamin E in relation to its role on formation PAHs in grilled meat. The results of this research could provide a theoretical basis to better understand the potential inhibitory role of vitamin E on the PAH formation and to gain insight into how the muscular endogenous levels of vitamin E could be a preventive agent for mutagen formation in grilled meat.