Recontamination of pasteurized milk - Still a problem in daily practice

Provided an appropriate cooling the shelf life of pasteurized milk depends on the contamination rate with heat sensitive, psychrotrophic microorganisms. In the case of optimum GMP conditions this can be extremely reduced. Results of Austrian dairies have shown a range of recontamination rates between 3 - 4 log units. Control of recontamination is therefore the main task for producers of pasteurized milk. The knowledge of generation time of the main contaminants at the cooling temperature makes a prognosis possible about the microorganisms' growth and shelf life of the products. This is one of the most simple examples of predictive microbiology. Our own results give some examples for several coliform species and they also show the connection between spoilage and storage temperature. The wide range of contamination rates needs different methods for evaluation. A catalogue of methods summarized by an IDF expert group allows the choice of the most easy, quick and sensitive method for each level.