Quantitatively determine pathogen reduction.

Our understanding of foodborne pathogens and of the types of microorganisms that have been linked with documented outbreaks of illness has dramatically increased in the past two decades. So now it's necessary to enhance our approach to pathogen control and food preservation by developing and implementing new biological, chemical and physical techniques.

The efficacy of a preservation technology is influenced by a number of microorganism-related factors that are independent of the technology itself. These include the genus, species and strain of the target pathogen, its growth stage and its stress selection mechanisms. Each of these factors influences the resistance of a microorganism to a preservation process, independent of the apparent inactivation ability of that particular process.

We need a quantitative knowledge of the factors in food systems that interact and influence the growth and inactivation kinetics of foodborne pathogens to accurately estimate how a particular pathogen is likely to behave in a specific food. There is a need for a better understanding of how the interaction among preservation variables can be used for predicting the safety of minimally processed ready-to-eat foods. Complex multifactorial experiments and analysis are a must in order to quantify the effects and interactions of intrinsic and extrinsic factors and to develop enhanced predictive models.

Over the next five years, USDA-ARS researchers will undertake a project aimed at developing intervention strategies for controlling foodborne pathogens. The program will focus on:

* Developing strategies to ensure the safety of thermally processed foods by quantifying the heat treatment required to achieve a specific lethality of foodborne pathogens;

* Assessing the effect of additives on the fate of C. perfringens during cooling after thermal processing;

* Controlling pathogens in ready-to-eat products by post-processing or the packaging application of treatments;

* Elucidating the cellular and molecular mechanisms of increased resistance of pathogens, and developing novel food preservation systems for the safe production of foods processed using milder preservation technologies; and

* Identifying factors affecting the attachment of foodborne pathogens to meat and attempting their removal by using combinations of chemical and biological approaches.

Predictive models rapidly give accurate estimates of pathogen survival during cooking, and they can estimate bacterial growth during the cooling of cooked foods. They allow food processors to formulate foods to include intrinsic barriers. Models can assess the microbial risk of a particular food and help us design reduced thermal processes that ensure safety against pathogens in ready-to-eat foods.

The models aid in designing HACCP programs, setting critical control levels and evaluating the relative severity of problems caused by process deviations. Further, they estimate the expected effectiveness of corrective actions. The basic research which is an integral part of this project provides new insights into the biochemical and molecular mechanisms underlying the increased heat resistance of pathogens.

Further information. John Luchansky, USDA-ARS Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038; phone: [phone]; fax: [phone]; email: [e-mail].