Thermal Food Processing

Thermal Processing of Meat Products 183
Log CFU/g or mL
Shoulder
Linear
Time
Linear
FIGURE 6.12 Graphic representation of shoulder and tailing in microbial populations
during thermal treatments. (Courtesy of Dr. Vijay Juneja.)
In cases where extreme deviations from first-order kinetics are observed in
thermal kinetics of microorganisms, it may be too simplistic to apply the general
method of calculating the process lethality, and in most instances, it could be
potentially hazardous. In such cases, it may be necessary to conduct microbial
challenge studies (MCTs) and simulate natural conditions encountered during
processing of a particular meat product. General guidelines for such challenge
studies have been published and, in most cases, were developed for specific purposes,
such as conduct of the MCTs for survival/destruction of L. monocytogenes
on ready-to-eat meat products. 55
In addition to these factors, process lethalities also depend on the processing
schedules employed, e.g., the time when moist heat was introduced, the
degree of dry heat vs. moist heat processing, product surface characteristics,
initial moisture of the product, and degree or rate of moisture loss, among
other factors.
6.8 PREDICTIVE MODELING OF THERMAL
DESTRUCTION KINETICS OF
VEGETATIVE PATHOGENS
Predictive modeling has gained popularity and wide acceptance from regulatory
agencies as a tool to evaluate and predict the microbiological safety of food
products. This probably is due to the regulatory shift from a prescribed command
and control system to a hazard analysis and critical control point (HACCP)-based
food safety approach.
Tail