Ionizing radiation is shown capable of serving as an effective sanitizing treatment improving the sanitary quality of shellfish and providing an increased margin of safety for shellfish consumers. 60Co irradiation of the hard‐shelled clam, Mercenaria mercenaria, and the oyster, Crassostrea virginica, significantly reduced virus carriage numbers without unduly affecting shellfish survival rates or desirable organoleptic qualities. A D10 value of 2 kGy was determined for depletion of hepatitis A virus in clams and oysters as measured by in situ hybridization fluorescent foci and cytopathology enumeration methods. A D10 value of 2.4 kGy was determined for depletion of rotavirus SA11 in clams and oysters as measured by a plaque forming unit enumeration method. Study results showed ionizing radiation capable of providing an extra, highly effective safeguard of shellfish sanitary quality when combined with traditional depuration treatment. Data drawn from other studies is introduced which shows D10 values as low as 1.0 kGy effectively eliminate Vibrio cholerae, and V. parahemolyticus, from shellfish.

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No abstract

When cod (Gadus morhua morhua) and headless white shrimp (Penaeus setiferus) were gamma irradiated with a series of low-ionizing radiation doses, a "shoulder(s)" was observed in the graph (log microbial counts versus dose) in the approximate range of 25 to 75 krads. When the microbiological survivors were differentiated into total counts, proteolytic and pseudomonad-type bacteria, it was observed that the pseudomonad-type bacteria were rapidly destroyed by 25 krads and that proteolytic bacteria were destroyed at a faster rate than the rest of the microorganisms. When cod fillets and shrimp were compared with their respective homogenates and irradiated at doses of 0, 10, 20, 30, 40, 50, 60, 80, 100, 150, 200, and 300 krads, the homogenates did not exhibit the characteristic shoulders. A further experiment was designed to test surface versus uniform dispersion of microorganisms on/in gelatin disks subjected to low doses of irradiation. Differences were found that may explain the observed differences between solid food materials such as fish fillets and shrimp and their homogenates.