INACTIVATION OF LISTERIA-MONOCYTOGENES IN MILK BY PULSED ELECTRIC-FIELD

Pasteurized whole, 2%, and skim milk were inoculated with Listeria mon ocytogenes Scott A and treated with high-voltage pulsed electric field (PEF). The effects of milk composition (fat content) and PEF paramete rs (electric field strength, treatment time, and treatment temperature ) on the inactivation of the bacterium were studied. No significant di fferences were observed in the inactivation of L. monocytogenes Scott A in three types of milk by PEF treatment. With treatment at 25 degree s C, 1- to 3-log reductions of L.. monocytogenes were observed. PEF le thal effect was a function of field strength and treatment time. Highe r field strength or longer treatment time resulted in a greater reduct ion of viable cells. A 4-log reduction of the bacterium was obtained b y increasing the treatment temperature to 50 degrees C. Results indica te that the use of a high-voltage PEF is a promising technology for in activation of foodborne pathogens.