Toxin production by C. botulinurn type E was studied in cod, whiting, and flounder filets packaged in air-permeable film, vacuum packages and packages flushed with Nz or CO2 during storage at 8'; 12") or 26'C. Cod and whiting filets were flushed with CO2 and stored continuously at 4'C or cycled between 4" or 8' and 26°C. Cod and whiting fillets were flushed with gas mixtures and stored at 8'C or 26'C. Flounder deteriorated rapidly and was rejected by sensory evaluation prior to toxin detection during vacuum or modified atmosphere storage at 12"C and 8'C but after toxin detection at 26°C. Toxin was present either prior to or simultaneously with sensory rejection of cod and whiting fillets for all vacuum or modified atmosphere treatments and temperature regimens.

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Activities of glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12) (GAP-DH) and aldolase (EC 4.1.2.13) in cells of Clostridium perfringens that had been inhibited with sodium nitrite were investigated. A complete loss in GAP-DH activity and a 67% decrease in aldolase activity were observed when growth of C. perfringens was inhibited. There was also a 91% decrease in the concentration of free sulfhydryl groups of soluble cellular components. Dithiothreitol restored some activity to inactive GAP-DH from sodium nitrite-inhibited cells, indicating that a loss of reduced sulfhydryl groups was involved in the inactivation of the enzyme. The evidence presented suggests that sodium nitrite inhibition of C. perfringens may involve an interaction of sodium nitrite as nitrous acid with sulfhydryl-containing constituents of the bacterial cell.

Quality audit data collected as part of a mass feeding quality assurance program were analyzed to determine the relationships between the indicator tests (total aerobic plate count, coliform count and Escherichiu colz) and the common food-borne pathogens (Staphylococcus aureus, Clostridium perfringens and Salmonella). 132 raw foods and 593 readyto-eat foods were evaluated. The indicators were grouped into ranges and compared to the pathogens and to each other in terms of detectability. There were correlations between the pathogens and the indicator ranges and between the indicators and the indicator ranges. The value of the indicators in the e'valuation of food safety was tested by setting standards and determining the numbers of correct and incorrect decisions which would be made relative to the pathogens detected in the foods. None of the indicators was suitable as a screening agent for food safety.

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