[Predictive microbiology and risk assessment]

Predictive microbiology (predictive modelling PM), in spite of its limits and short-comings, may often contribute to a reduction of the problems arising when HACCP systems are established or microbiological risk assessment is done. Having identified the agents which constitute a risk and the contamination rate and density in the raw material, the influences of production steps and storage on these microorganisms have to be examined. Finally, there should be an exposure assessment, i.e. an estimate of the contamination density in the final product at the time of consumption. Should the exposure assessment together with data from dose response assessments reveal a potential for intake of inacceptable numbers of organisms, the risk identified has to be characterized. As a consequence, risk management should result in a modification of the composition of the product and/or of the production process so that the risk does not surpass an acceptable limit. For this approach it is indispensable to have product- and process-specific information on the multiplication of pathogens prior to heat treatment, on reduction of their density by thermal treatment and on growth or dying of organisms having survived heat treatment or penetrated into the product after heat treatment as post-process contaminant. Commonly, challenge tests are conducted to provide such information. But they are time consuming and, as their results are only valid for the specific product tested and the conditions prevailing during the experiment, the have to be repeated if there is any modification of intrinsic or extrinsic factors. At least partially, the PM may replace the challenge tests. The efficiency of the models is rated particularly high if they are used already at the stage of product development when the question has to be answered whether a planned recipe or process of production are already save or have to be modified to become save.