Clostridium Botulinum Type E in Smoked Fish

SUMMARY A botulism outbreak in Minneapolis, Minnesota, in 1960, caused by Clostridium botulinum type E, is reported. Smoked eiscoes from the Great Lakes served as the vehicle for the food poisoning. Smoked ciscoes inoculated with type E spores and held at 30°C in packages open to the air became toxic as rapidly as those incubated under anaerobic conditions in plastic air‐tight wrappers. Surface spoilage developed more rapidly in the open packages. Toxin was not produced within 31 days in fish incubated at 5°C; however, mold and bacterial growth was noted after fish were open to the air 18 days. Vacuum packaging markedly increased the shelf life of the product by suppressing the development of visible bacterial and mold growth. Toxin was demonstrated in inoculated smoked fish incubated in the original plastic wrapper at 10°C for 5 days without any signs of quality reduction. Within 18 days at 10°C, half the fish contained toxin although there was no noticeable evidence of spoilage. At higher temperatures within a given time, a greater percentage of fish contained toxin. A survey of procedures employed in “hot‐smoking” of fish is reported, and data are presented on levels of salt and moisture, brine concentration, and free liquid of both vacuum‐packaged and bulk‐pack smoked fish.