Development and application of a fast method for quantification of the thermoresistant, bacterial, proteolytic activity in raw milk (PROMILK)

The general goal of the PROMILK project is to develop a fast and simple method to assess heat-resistant proteolytic activity in raw milk. During refrigerated storage of raw milk on the farm and at the dairy company before processing, the growth of psychrotrophic (cold-tolerant) microorganisms belonging mainly to the pseudomonads is promoted.  These may form heat-resistant enzymes that may cause milk spoilage. These enzymes stay active after UHT-treatment or sterilization and may be the cause of sensory and stability problems before reaching the end of the shelf-life. This may lead to complaints and possibly to a recall of the product in question. 

First, we develop a fast method to assess the heat resistant proteolytic activity, which can preferably be used at the company itself. This comprises the optimization of the sample preparation as well as the detection methodology. The developed method will subsequently be validated functionally as well as analytically. Second, the influence of Pseudomonas numbers in raw milk on milk stability/taste is studied. Also the effect of teat disinfection or disinfection of teat cup linings on numbers of Pseudomonas in raw milk will be analyzed.