Adiabatic heat modelling for pressure build-up during high-pressure treatment in liquid-food processing

Pressure build-up is always accompanied by an increase of temperature in the product due to the transformation of energy during compression. Pure water and sucrose solutions were pressurized up to 600 MPa starting from different initial temperatures. The thermal history at the centre of the product was recorded and then related to the change in the thermo-physical properties of the product as a function of pressure, temperature and solid content. These thermo-physical properties were incorporated into a model equation and the predictions were compared with NIST (National Institute of Standards and Technology, Gaithersburg) database formulations-no significant deviations between the results and model predictions were found. Comparing the predicted results for sucrose solutions with the adiabating heating of a real product like orange juice also resulted in no significant deviations. The temperature distribution was then modelled all over the sample and used to predict the inactivation of relevant microorganisms in orange juice.