Growth of the cold-tolerant pathogens Yersinia enterocolitica, Aeromonas hydrophila and Listeria monocytogenes on high-pH beef packaged under vacuum or carbon dioxide

Strains of the cold-tolerant pathogens Yersinia enterocolitica, Aeromonas hydrophila and Listeria monocytogenes were inoculated onto samples of high pH (>6.0) beef. Samples were packaged under vacuum or under CO₂ and stored at -2, 0, 2, 5 or 10 °C. In vacuum packs, Y. enterocolitica and A. hydrophila grew at all storage temperatures at rates similar to or faster than those of the spoilage flora. The lags before growth of Y. enterocolitica at 0, 2 and 5 °C, and of A. hydrophila at 10 °C were insignificant relative to the proliferation of the spoilage flora. L. monocytogenes did not grow in vacuum pack at -2 °C, and at higher temperatures generally grew at rates less than that of the spoilage flora after relatively long lag periods. In CO₂ packs, all three organisms grew at 10 °C, but only Y. enterocolitica grew at 5 °C and then relatively slowly after a prolonged lag. None of the organisms grew in CO₂ packs at 2 °C or lower temperatures. © 1989 Academic Press Limited.