USE OF ESR SPECTROSCOPY FOR THE DETECTION OF IRRADIATED CRUSTACEA

Frozen whole tail sections of pink shrimp (Pandalus montagui), tiger p rawn (Penaeus monodon), king prawn (Penaeus plebejus) and Mediterranea n crevette (Palaemon serratus) were defrosted overnight and either irr adiated the following day with doses of 1, 3 and 5 kGy or left unirrad iated. Following irradiation the samples were stored for 0, 7, 14 or 2 1 days at 1 degrees C after which the cuticle was removed, freeze-drie d and ground prior to derivation of the electron spin resonance (ESR) spectra. The shape of the ESR signals derived from the irradiated cuti cle of the four species were not identical. Subtraction of an average control spectrum from each species from that induced in the correspond ing irradiated samples resulted in the isolation of a number of free r adical peaks, the heights of which were measured and the sum of the va lues used as a measure of signal intensity. Both the irradiation dose and length of storage had a highly significant effect on signal intens ity. The signal derived from the cuticle of the Mediterranean crevette was the most stable. The isolated radiation-induced signals from all four species given 3 and 5 kGy were detectable in samples stored at 1 degrees C for at last 14 days.