PREDICTIVE MICROBIOLOGY - USES FOR ASSESSING QUALITY AND SAFETY OF DAIRY-PRODUCTS

Predictive growth models can be used to predict the shelf-life of products at any point from processing to purchase and to assist manufacturers devise suitable preservation strategies that inhibit the growth of spoilage and pathogenic organisms to an acceptable extent. A number of spoilage models for raw and pasteurized milk and cottage cheese are presented. In most fermented dairy products, the vigorous metabolic activity of starter cultures prevents the growth of pathogens which limits the value of predictive models. Such modeling does however have application, particularly with respect to temperature abuse, in products such as pasteurized milk and cream where the perceived 'naturalness' of the product prevents the use of chemical preservatives. Two models describing the growth of Listeria monocytogenes are presented. It must be remembered that it is not sufficient to observe that a model appears to work: it is important to know why it works which emphasizes the need for continued fundamental studies on the physiology of microorganisms to underpin the more applied aspects of modeling research.