Their presence in a pasteurized product is indicative of insufficient thermal processing, unsanitary conditions during processing or post-pasteurization contamination. Standard Plate Count . This is a test for the total bacteria per unit weight or volume of pasteurized product. Phosphatase Test . This test checks for the completeness of pasteurization.
All raw milk contains the enzyme phosphatase.
Over all the ranges of time-temperature heat treatments recognized for proper pasteurization, all pathogenic bacteria likely to be present in raw milk, are destroyed more quickly than phosphatase is inactivated. Therefore, if a positive phosphatase test occurs, it could be due to improper pasteurization or the contamination of a pasteurized product with a non-pasteurized product. Psychrotrophic Bacteria . Fluid milk products are checked for the presence of psychrotrophic bacteria. These are bacteria that grow well at refrigeration temperatures, and could cause product spoilage, even under refrigerated storage conditions if initial numbers are too high.