Oxygen sensitivity of heated cells of Escherichia coli O157:H7

• Autores: S.M. George, R. Bromberg, M.W. Peck
• Localización: Journal of applied microbiology, ISSN 1364-5072, Vol. 85, Nº 2, 1998, págs. 231-237
• Idioma: inglés
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• Resumen

  • Following defined heat treatments (55 °C for 100 min, 59 °C for 5 min, 61 °C for 1 min), a 6 decimal (6‐D) reduction was obtained when cells of Escherichia coli O157:H7 were enumerated in aerobic growth medium. Part of this reduction (3‐D) was due to thermal inactivation (as determined when cells were enumerated in anaerobic growth medium), and part (3‐D) was due to the inability of sub‐lethally heat‐injured cells of E. coli O157:H7 to grow in the presence of oxygen. When held anaerobically, the injured cells regained their ability to grow in the presence of oxygen. Following heating at 59 °C for 5 min, repair took 4 h at 30 °C, 48 h at 20 °C, 95 h at 10 °C, but did not occur in 816 h at 5 °C. Recovery from sub‐lethal heat injury was not influenced by heat shock. These findings are relevant to the safety of minimally‐heated foods.