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TDK conference 2018

Chemical safety of street foods: what do we eat with the gyros?
Szijjártó József - year 6
University of Veterinary Medicine Budapest, Department of Food Hygiene
Supervisor: Dr. Katalin Lányi


Baking and grilling meats at high temperatures, using open flames has been applied by humanity since ancient times. Cooking-baking serves better digestibility of foods, improves microbiological food safety and flavour. However, heat treatment can not only have positive effect on the safety of foods. One typical example is the formation of carcinogenic, genotoxic heterocyclic aromatic amines (HCA). At temperatures above 150 ° C, HCAs are produced from the natural ingredients of the meat. The resulting amount of HCAs is largely dependent on variable factors such as baking temperature, baking method and time, meat type, moisture content, pH, sugar, free amino acids and creatinine concentrations, as well as antioxidant and lipid oxidation. Today, numerous studies address the effects of HCAs on human health. Both the US FDA and the International Agency for Research on Cancer (IARC) have stated that certain HCAs may be related to certain cancers of the digestive tract and other cancerous diseases. As a result, the formation of HCAs during baking and cooking processes and the control of their quantity is paramount importance.

During my research I studied three thermal HCAs: MeIQ, MeIQx, PhIP; and two pyrolytic HCAs: harman and norharman. The latter two compounds are not directly classified as carcinogenic, but their presence enhances the carcinogenic effect of the previous group. The dishes were divided into parts according to their ingredients: in the case of gyros, meat, pita and vegetables, in the case of falafel, balls of onion and chick peas, pitas and vegetables. After the appropriate sample preparation I examined the HCA content of the samples using a previously developed LC-MS / MS method.

According to the measurement results, in most cases, the HCA content of the meat itself is significantly higher than the rest of the ingredients. The full HCA content of the tested fast foods - with few exceptions - remained below the level of health hazard. At the same time, surprising, unexpected results were also experienced for some HCAs. Even raw vegetables - which could not contain HCA due to their composition or heat treatment - were not completely free from these compounds. It can be clearly stated that cross-contamination has great significance not only from a microbiological but also from a chemical point of view in food safety. Devices and tools getting in contact with this fried or baked meat can also play a role. Harman and norharman were also found in the pita, which was not a surprise given that the protein content of the plants could also be the starting point for the reaction to the HCAs. In the light of our results, it can be stated that gyros and falafel made from open flames and high-temperature do not pose a significantly higher food safety risk than any other fried meat.

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