The lactoperoxidase (LP) system is a naturally occurring system which was first discovered in raw milk. Different groups of bacteria show a varying degree of resistance to the LP system. Gram-negative catalase-positive organisms, such as pseudomonads, coliforms, salmonellae, and shigellae, are inhibited by the LP system. Depending on the medium pH, temperature, incubation time, cell density, and the particular donor, these microorganisms may be killed. It has been shown that the LP system can increase storage times of raw milk by delaying growth of psychrotrophs; perhaps this method could be used to extend the shelf life of other foods.
Published as Paper No. 10320, Journal Series, Nebraska Agricultural Research Division, Lincoln, NE 68583-0919.