References

Alavi S H, Puri V M, KNABEL S J, MOHTAR R H AND Whiting R C (1999), Development and validation of a dynamic growth model for Listeria monocytogenes in fluid whole milk. J Food Prot, 62, 170-6. AUGUSTIN J C AND Carlier V (2000a), Mathematical modelling of the growth rate and lag time for Listeria monocytogenes. J Food Microbiol, 56, 29-51. AUGUSTIN J C AND Carlier V (2000b), Modelling the growth rate of Listeria monocytogenes with a multiplicative type model including interactions between...

Microbial stress adaptation and crossprotection

Microbial cells sense stress (e.g. disruption of ribosomes as a result of heat or changes in cell membrane fluidity during cold shock), and this triggers protective responses against the sensed deleterious conditions. These responses involve physiological adaptations, which counterbalance stress damage and allow the cells to continue their growth and ensure their survival. Microorganisms also respond to stress induced by inherent physiological change. Entry into the stationary phase, for...

Blocking infection

Although prevention of foodborne disease is preferable to treating it, we are still far from achieving this admirable goal. Furthermore, resistance to the frontline antibiotics is spreading among foodborne pathogens, making treatment of infections more difficult (McDermott et al., 2002 White et al., 2002). Continued research into prevention and treatment strategies for foodborne pathogens is, thus, a necessity. Some of the alternative strategies to blocking infection being pursued include the...

Pathogenic cell adhesion and invasion 431 Adhesion

Just as the human host has evolved multiple mechanisms to prevent infection by pathogenic microorganisms, the microorganisms themselves have evolved diverse and effective mechanisms that thwart their host's defense mechanisms to enable successful infection. As previously mentioned, for example, many bacteria have evolved stress response systems that enable them to survive highly acidic conditions such as those encountered during passage through the human stomach. After reaching the intestine,...

Primary models

2.3.1 Dynamics of bacterial population growth Dynamics of a bacterial population of size x as a function of time can be seen as a succession of three phases (Fig. 2.1) 1. A lag phase which is associated with the physiological adaptation of the cells to their new environment, prior to growth. 2. An exponential growth phase where the logarithm of the bacterial population increases linearly with time. The slope of this linear portion, when the natural logarithm of the bacterial concentration is...

Info

-Type terms for pH and lactic acid effects on growth rate were also included in square-root type models by Presser et al. (1997) and Ross et al. (2003). Introduced by Rosso et al. (1993, 1995), the cardinal parameter models (CPMs) were also developed according to the Gamma concept. The relative effects of temperature, pH and water activity on the bacterial growth rate are described by a general model called CMn (X -X )-1 (X -X )(X-X )-(X -X ) (n-1)X +X -nX) v opt min' opt min7 v opt7 v opt...

Processing conditions producing sublethal injury

Foods and food ingredients may be subjected to a variety of processes to achieve preservation against microbiological spoilage and pathogenic microorganisms or toxins. The treatments may result in viable microorganisms that are physiologically deficient or injured because of the stress to which the cells have been subjected Ray and Adams, 1984 Budu-Amoako et al., 1992 . Concern has been expressed about the ability of heat-injured foodborne pathogens to resuscitate during processing treatments,...

Host defense mechanisms and pathogen survival strategies

4.2.1 Non-specific human host defense mechanisms There are multiple human host defense mechanisms acting all along the human gastrointestinal tract that help prevent infection by foodborne bacterial pathogens. These include non-specific defenses against all bacteria as well as defenses specific to particular pathogens that are part of an adaptive immune response. Some of the body's non-specific defenses include the acidic pH and proteolytic enzymes in the stomach, detergents and flushing action...

Woodhead Publishing Limited

Published by Woodhead Publishing Limited, Abington Hall, Abington, Published in North America by CRC Press LLC, 6000 Broken Sound Parkway, NW, Suite 300, Boca Raton, FL 33487, USA First published 2005, Woodhead Publishing Ltd and CRC Press LLC The authors have asserted their moral rights. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. Reasonable efforts have been made to publish...