Activity of Goats' Milk Lactoperoxidase System on Pseudomonas fluorescens and Escherichia coli at Refrigeration Temperatures

Zapico, P.; Gaya, P.; Nuñez, M.; Medina, M.

doi:10.4315/0362-028x-58.10.1136

Bactericidal activity of the lactoperoxidase (LP) system against Pseudomonas fluorescens was observed in refrigerated raw goats' milk. Mean decreases in the levels of P. fluorescens of 1.69 log units at 4°C and 1.85 log units at 8°C were achieved during the first 24 h by LP-system activation. Inhibitory activity depended on temperature and length of incubation. P. fluorescens counts lower than the initial level were recorded in activated LP-system milk for 5 days at 4°C and 3 days at 8°C. Escherichia coli did not grow in raw goats' milk at 4°C, and the influence of LP-system activation at this temperature on E. coli counts was negligible. At 8°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-system milk at 8°C, resulting in lower E. coli counts than those of control milk during the first 5 days.