ANTIBOTULINAL PROPERTIES OF NISIN IN FRESH FISH PACKAGED IN AN ATMOSPHERE OF CARBON-DIOXIDE

The inhibitory effect of nisin on toxin production by Clostridium botulinum type E in inoculated cod, herring, and smoked mackerel fillets, packaged in a 100% carbon dioxide atmosphere, was studied at storage temperatures of 10 and 26°C. Nisin delayed the onset of toxin production in all three fish species. The nisin effect was marked at 10°C and delayed the onset of toxin production by at least 5 d beyond that of the controls. At 26°C the delay was shorter, being one-half day for cod, one day for herring, and two days for smoked mackerel. Nisin did not affect the time to spoilage by nonpathogenic bacteria at either temperatures of storage. It was noted that toxin was formed in untreated cod, mackerel, and herring stored at 26°C and in mackerel stored at 10°C before the samples were judged to be unacceptable to the consumer. Copyright © International Association of Milk, Food and Environmental Sanitarians.