DETECTION OF GAMMA-IRRADIATED RAW-MILK CAMEMBERT CHEESES BY CAPILLARY GAS-CHROMATOGRAPHIC ANALYSIS OF VOLATILE HYDROCARBONS

A method to detect the irradiation of raw-milk Camembert cheeses by gas chromatographic analysis of radio-induced volatile hydrocarbons, formed by radiolysis of myristic, palmitic and stearic acids, is proposed. The presence, in the sample, of tridecane, 1-dodecene, 1-tetradecene and 1-hexadecane, in association with an increase in levels of pentadecane and heptadecane, can be considered an indication of irradiation. Moreover, the quantity of radio-induced volatile hydrocarbons, formed from the same fatty acid precursor, is proportional to the fatty acid composition in the sample and the 1-alkene/alkane ratio remains constant (similar to 13) and independent of the fatty acid precursor. In spite of the hydrocarbon stability during ripening and storage and the good linear correlation between the hydrocarbon concentration and the irradiation dose (up to 397 kGy), the determination of the latter is approximate because of the experimental error (+/-20%) and the possible fluctuations of certain parameters of the ionizing treatment (e.g. temperature and dose rate).