ACTIVITY OF GOATS MILK LACTOPEROXIDASE SYSTEM ON PSEUDOMONAS-FLUORESCENS AND ESCHERICHIA-COLI AT REFRIGERATION TEMPERATURES

Bactericidal activity of the lactoperoxidase (LP) system against Pseud omonas fluorescens was observed in refrigerated raw goats' milk. Mean decreases in the levels of P. fluorescens of 1.69 log units at 4 degre es C and 1.85 log units at 8 degrees C were achieved during the first 24 h by LP-system activation. Inhibitory activity depended on temperat ure and length of incubation. P. fluorescens counts lower than the ini tial level were recorded in activated LP-system milk for 5 days at 4 d egrees C and 3 days at 8 degrees C. Escherichia coli did not grow in r aw goats' milk at 4 degrees C, and the influence of LP-system activati on at this temperature on E. coli counts was negligible. At 8 degrees C, E. coli was able to grow in control milk with no apparent lag phase . In contrast, a lag phase of 2 days was observed in activated LP-syst em milk at 8 degrees C, resulting in lower E. coli counts than those o f control milk during the first 5 days.