Kinetic Analysis of Microorganisms Inactivation in Apple Juice by High Pressure Carbon Dioxide

The interest towards cold pasteurisation of sensitive materials with high pressure carbon dioxide is growing more and more, especially for the applications to food products (1). The aim of this work is to study the kinetic inactivation of microorganisms naturally present in fresh apple juice, carried out in multi-batch equipment. Three operating parameters have been considered and discussed: temperature, pressure and volume treated. The results obtained confirm that high pressure Carbon Dioxide is effective for microbial inactivation even on particularly complex materials such as fruit juice. Temperature plays a fundamental role on treatment efficiency, with inactivation being significantly enhanced increasing its value from 20 to 36 degrees C. The same trend was not observed for different pressures (60-100-200 bar). As far as the mass transfer between the fluid and the liquid phase is concerned, a high ratio between the surface and the sample volume (a low sample volume) exerts an important effect on the inactivation efficiency of the species considered. The results seem promising for a future development of industrial applications of high pressure Carbon Dioxide treatment on apple juice.