Optimisation of the formulation and of the technological process of egg-based products for the prevention of Salmonella enteritidis survival and growth

The aim of this work was to study the survival of Salmonella enteritidis after a pressure treatment in relation to compositive variables (NaCl content, pH), both in model and real systems, the latter consisting in an egg-based mayonnaise type product. Moreover, the fate of the surviving cells of S. enteritidis has been monitored during storage at 10 degrees C and the growth or death parameters have been calculated and modelled in relation to pH, NaCl concentration of the medium and entity of the pressure treatment applied. The modelling of the effects of the environmental factors on the treatment effectiveness indicated that the salt content and pH displayed a synergistic effect with pressure, whose extent was higher in the mayonnaise based products than in BHI. In fact, while in the model systems the cell recovery and growth during the subsequent incubation at 10 degrees C was allowed in many combinations of the Central Composite Design, in the real systems no recovery or growth of S. enteritidis were observed. This viability loss, which was maximum at pH 4.00 or 2% NaCl, could not be attributed merely to the interactions of such variables, but probably involves the naturally occurring antimicrobial enzymes of the raw material, whose activity can be enhanced by the pressure treatment.