Thermal inactivation of Escherichia coli O157:H7

Verotoxin-producing Escherichia coli O157:H7 is a cause of serious foodborne illness. It has a very small infectious dose and so it is vital to eliminate this pathogen from food. As heat treatment is the method of bacterial destruction most frequently used in food processing, accurate prediction of thermal death rates is necessary to achieve desired safety margins whilst minimizing processing. In most studies thermal inactivation has been described using first-order reaction kinetics and D-values. Whilst this approach does not seem justified on a theoretical basis, and may increase inaccuracy, there is no doubt that it is convenient and in many cases provides an adequate description of thermal death. A review of published data on the measured thermal inactivation of E. coli O157:H7 shows no strong evidence that a heat treatment of 70 degrees C for 2 min (or equivalent) fails to deliver a 6-decimal reduction in cell numbers.