Thermal inactivation ofEscherichia coliO157:H7

Abstract

SUMMARY 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°C for 2 min (or equivalent) fails to deliver a 6‐decimal reduction in cell numbers.

Effect of Challenge Temperature and Solute Type on Heat Tolerance of Salmonella Serovars at Low Water Activity

“…at low a w . Thermal inactivation models are published elsewhere for Salmonella (52 to 59°C and high a w [17] and 55 to 65°C and 0 to 9% NaCl [8]) and for Escherichia coli O157 (52 to 60°C and 8% NaCl [57], 54 to 68°C with 9 or 17% NaCl [11], and 55 to 65°C and 0 to 9% NaCl [8]). There is very little available information, however, on the inactivation of these pathogens at higher temperatures (65 to 80°C) in combination with lower a w (rvp.0.65 to 0.90), particularly when the a w is depressed using solutes other than NaCl.…”

Principles and Methodologies for the Determination of Shelf-Life in Foods

“…curves exhibiting a "shoulder" region at the beginning of the inactivation curve and/or a "tail" region at the end of the inactivation curve. Stringer et al (2000) summarized the possible explanations for this behavior. Some of them are the variability in heating procedure, the use of mixed cultures, clumping, protective effect of dead cells, multiple hit mechanisms, natural distribution of heat sensitivity or heat adaptation.…”

“…We now know that cells do not exist simply as alive or dead, but may also experience various degrees of injury or sublethal damage, which may give rise to apparent nonlinear survival curves (Stringer et al, 2000). Survival modeling should also include a more complete understanding of the molecular events underpinning microbial resistance to the environment.…”

Organic Cultivation of Tomato in India with Recycled Slaughterhouse Wastes: Evaluation of Fertilizer and Fruit Safety

“…Thus, in consonance with the cited literature, low numbers of microbes were detected in BBRDM as the product was processed at a temperature higher than the inactivation temperatures of most disease-causing germs. However, it should be considered that the inactivation kinetics of foodborne pathogens is closely linked to the menstrum in which they reside [25].…”

“…Pasteurization-like treatment may be a suitable option for lowering pathogen loads in slaughterhouse wastes, so that land application may be possible with minimum biological risk [13]. A variety of factors affect the thermal destruction rate of pathogens such as growth conditions (strain specificity, logarithmic or stationary growth phase and heat shock); the heating method applied (local temperature variations and open or closed heating systems); the heating menstrum (nature of proteinaceous matter, its fat, moisture and salt contents and pH of the menstrum) and finally the recovery conditions applied after heat treatment (pour or spread plate, media composition and aerobic or anaerobic incubation) [25]. Most likely, the possibility of blood waste contamination with E. coli O157:H7 is low.…”