Formation of mutagenic and cancerogenic heterocyclic aromatic amines in model systems and their quantitative determination in model systems and foods

The formation and the reaction mechanism of the heterocyclic aromatic amine, PhIP (2-amino-l-methyl-6- phenylimidazo[4,5-b]pyridine), shall be investigated in a conventional system (diethylene glycol, phenylalanine, creatinine) with non labelled compounds. Then the experiments shall be carried out with labelled compounds (phenylalanine, phenylacet-aldehyde). The intermediates and the end products shall be isolated and then identified by NMR measurements. In a more realistic model system diethylenglycol is replaced by an edible oil with definite composition and the experiments shall be carried out under realistic conditions in respect to the edible oil, temperature and time of cooking. The formation:,of PhIP and other HAAs shall be examined. Additionally the influence of antioxidants and prooxidants on the forination of HAAs shall be investigated. In the analytical part of this project at first the HAAs shall be determined qualitatively and quantitatively in model systems using an optical (UV- or fluorescence) or an amperometric detector in combination with HPLC. Then for coulometric detection with the electrode array detector the electrochemical fundamentals of HAAs shall be investigated. From these data the optimal conditions, for the oxidative and the oxidative-reductive detection mode shall be derived. The detection system combined with a HPLC apparatus shall be applied to the determination of HAAs in different types of meat (chicken, turkey, pig, game), which are prepared under definite conditions in respect to the type of oil, spices, temperature and time of cooking. In this way it shall be found out if the type of meat influences which HAAs and in which extent such compounds are formed. Additionally foods which were prepared in restaurants, butcher shops or fast food shops shall be analysed to get an insight in the content of HAAs in commercial available foods in Austria.

Heterocyclic aromatic amines are formed cooking (broiling, frying) meat. These compounds are mutagenic and cancerogenic and therefore their quantitative determination in foods is necessary to evaluate the daily intake of humans. It is also important to elucidate the reaction mechanism of the formation of these compounds and to study the influence of other substances (oil, spices) on their formation. In this way one gets an information in what way the formation of these compound can be decreased. In this project the reaction mechanism for formation of one heterocyclic aromatic amine in a model system was elucidated and the influence of temperature and heating time on the formation was explained. It could be shown that addition of spices to the reaction mixture decreases the content of this heterocyclic aromatic amine. For the investigation of commercial (soups, broiling fats, fast foods) and self cooked foods (patties, grilled chicken) an analytical method was developed and up to seven heterocyclic aromatic amines could be identified and quantified. The concentration of these compounds are between 0.3 and 2.8 g/kg. It could be demonstrated that meat prepared at higher temperatures contain an increased level of heterocyclic aromatic amines. Especially the crust of the chicken meat or the patty contain higher concentrations of heterocyclic aromatic amines as the inside of the meat. That means that meat should not be heated to long at higher temperatures to avoid the formation of a thick crust.