Botulinal toxin production in vacuum and carbon dioxide packaged meat during chilled storage at 2 and 4C

This study was undertaken to determine if carbon dioxide packaging of meat afforded a food safety advantage over vacuum packaging with respect to botu linal toxin production during chilled storage. A cocktail of washed spores from five toxigenic clostridial strains - four reference Clostridium botuli num strains [types A, B (2 strains) and E] and a C. butyricum type E strain - was inoculated onto lamb chumps. Of these strains, two were psychrotoler ant. The inoculated chumps were individually carbon dioxide packaged and du plicate packs were placed into storage at 10, 8 6, 4 and 2C. All storage re gimens included a weekly defrost cycle when meat surface temperatures incre ased by up to 6 to 7C during a 2 to 2.5 h period. After 84 days storage, pa cks were assessed for the presence of botulinal toxin using the mouse bioas say procedure. All packs contained botulinal toxin. To compare toxin produc tion in vacuum and carbon dioxide packs at chill temperatures, the challeng e trials were repeated for 4 and 2C storage. Packs were examined at regular intervals for toxin presence. Both pack types contained toxin after 21 and 48 days storage at 4 and 2C, respectively. In the unlikely, but not imposs ible, event that raw meat would be contaminated with psychrotolerant toxin- capable clostridial spores, product safety, with respect to botulinal toxin presence after prolonged chilled storage, requires storage temperatures to be maintained below 2C for both vacuum and carbon dioxide packaged product .