PSYCHROTROPHS IN DAIRY-PRODUCTS - THEIR EFFECTS AND THEIR CONTROL

Health concerns and technological effects of psychrotrophic bacteria i n dairy products are reviewed, as well as methods to control their pre sence and development. The various Gram-negative and Gram-positive psy chrotrophic species are listed and, with respect to pathogenic psychro trophs, emphasis is given on Listeria monocytogenes, Yersinia enteroco lytica, and Bacillus cereus. The influence of psychrotrophic bacteria on the quality of raw milk, pasteurized and UHT milks, butter, ice cre am, cheese, and powders is examined. Public health considerations of L isteria monocytogenes, Yersinia enterocolytica, and Bacillus cereus of these various dairy products are also presented. Methods that can be used to eliminate or control the development of psychrotropic bacteria include low or high temperatures, chemicals, gases, the lactoperoxida se system, lactic acid bacteria, microfiltration, bactofugation, lacto ferrin-related proteins, sanitation, flavors, and naturally occurring spore germinants.