Unfortunately, it is not rare that during preparation of food substances with cancerogenic and/or mutagen activity are unwillingly introduced into food. A typical representatives of this group of dangerous substances are N-nitrosamines (NAs) which are found in various meat products. Earlier we already spoke in this blog about the presence of these compounds in beer.

The formation of NAs in meat proceeds via so-called nitrosation reaction, which is a complex process and a large number of substances can influence the reaction. The “starting materials” for NA formation in meat products are nitrate, nitrite, primary, secondary, and tertiary amines, amides, proteins, peptides, and amino acids or precursors of these, which are transformed into NA precursors by microbial action. NAs are formed after cooking, by an oxygen-dependent mechanism, the key step being the oxidation of nitric oxide and the formation of higher nitrogen oxides, which could act as direct nitrosating agents. The nitrosating agent responsible for the formation of NAs in fried meat might be N2O3, formed during heating of nitrite in meat, or NO radical formed by dissociation of N2O3 at high temperature.
Of key importance in obtaining information on the content of NAs in food and possibilities for its reduction are reliable analysis methods for determination of NA concentrations. One such analytical method – based on the gas chromatography mass spectrometry – has been developed five years ago at the Tartu laboratory of the Estonian Health Board in collaboration with University of Tartu and published in journal Food Chemistry. It has been cited 9 times since its publication. The limit of detection and the limit of quantitation for this method were approximately 0.09 and 0.29 mkg/kg, respectively. The recovery of NAs in meat products varied from 79% to 88%, which can be considered very good for this kind of demanding analysis. Total concentrations of NAs in 386 studied samples of meat ranged from non-detectable to 30 mkg/kg. The highest levels of NAs were found in samples of fried meat. Relatively high level was found in grilled meat, in smoked pork, in half-smoked sausage, and in ham. With the addition of sodium nitrite, one can observe roughly linear increase in concentration of NAs in fried and raw meat. About 73% of NAs are concentrated in fat of baked mutton. In fried pork, the concentration of NAs in fat exceeds the concentration in lean 6 times. Apparently, the temperature and time of cooking, the method of cooking, residual and added nitrite concentration, the concentration of NA precursor and storage conditions of meat have a significant effect on the concentration of NAs (Image: Wikipedia).

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