proteolytic potential of pseudomonas fluorescens isolated from refrigerated raw milk

The growth rate and the proteolytic activity of Pseudomonas fluorescens strains 07A and 041, isolated from cow’s milk, were evaluated at 2, 4, 7 and 10ºC. P. fluorescens promoted protein degradation during storage of milk samples as observed by Proteolytic activity measurement, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and heat stability of milk. Casein hydrolysis resulted in loss of thermal stability of milk and in formation of fragments of low and medium molecular mass. Temperatures up to 10°C did not guarantee raw milk quality when contamination by P. fluorescens was equal or higher than 106 cfu/mL.