INACTIVATION KINETICS OF LISTERIA-INNOCUA IN SKIM MILK IN A CONTINUOUS-FLOW PROCESSING SYSTEM

Thermal inactivation of Listeria innocua in raw skim milk determined u nder continuous flow conditions was compared to results from the capil lary tube method at 65, 68, and 70 degrees C. A laboratory scale paste urizer (LSP) was used to generate kinetic data under isothermal, conti nuous-flow conditions. Inactivation was monitored by sampling at vario us locations along the hold tubes. D-(65 degrees C-), D-(68 degrees C- ) and D-(70 degrees C-)values for L. innocua M1 were 11.5, 3.5, and 1. 6 sec, respectively, when determined by the LSP system and 16.5, 3.9, 1.5 sec, respectively, when determined by the capillary tube method. D ecimal reduction times for the two methods were predicted to be coinci dent at 69 degrees C. Z(D)-values for the capillary tube and LSP syste ms were significantly different. The data suggest that the mechanism o f thermal destruction may be different between batch and continuous fl ow processes.