IDENTIFICATION OF IRRADIATED PASTEURIZED EGG PRODUCTS - A COMBINED METHOD TO USE IN ROUTINE CONTROL

Pasteurized egg products (whole egg, egg yolk and egg white) were test ed for irradiation treatment in the German food control laboratories i n Oldenburg/Niedersachsen and Kassel/Hessen as well as in the food irr adiation laboratory of the German federal health office. Gas chromatog raphic/mass spectrometric measurements on the fat components of egg-pr oducts showed clearly whether the product had been irradiated or not. While in unirradiated samples no traces of special hydrocarbons (accor ding to the fatty acid composition of egg) and no traces of the irradi ation-specific compound 2-Dodecylcyclobutanone were found, irradiated control samples as well as products of two belgian suppliers contained these substances. Additionally, regarding the rather high time consum ption of gaschromatography, electron spin resonance (ESR)-measurements were carried out on the packaging material of egg products. Irradiate d packaging material (cellulose) could be easily detected by the appea rance of a signal pair in the ESR spectrum (cellulose radical). ESR me asurements are very fast and easy to perform so that this method can b e used for screening. Microbiological investigations showed remarkably reduced total numbers of microorganisms for some irradiated samples, but the microbiological status is influenced by other factors like sto rage-time and -temperature, so that mikrobiological tests can not be u sed successfully for screening on irradiation treatment.