EFFECTS OF HOMOGENIZATION PRESSURE ON THE SURVIVAL AND GROWTH OF SOME FOOD SPOILAGE AND PATHOGENIC MICROORGANISMS

The effectiveness of pressures ranging from 150 to 2000 bar, applied by means of a continuous homogenizer, on the cell viability of spoilage or pathogenic micro-organisms, was evaluated. Moreover, the effects of microstructural modifications of food systems associated with the treatments on cell viability and on its subsequent evolution were investigated. Modulation of the homogenization pressure allowed strong instantaneous reductions of the initial numbers of Listeria monocytogenes, Yersinia enterocolitica, Bacillus subtilis and the yeast Yarrowia lipolytica. The combined effects of the initial pressure treatment and space reduction, resulting from the microstructural modifications of food systems, increased the safety and the shelf-life both of water in oil and oil in water emulsions.