Radio Frequency: New Technology Applications and Validation of Pathogen Reduction

Radiofrequency (RF) processing is a novel thermal processing technology. It is a form of dielectric heating in which the applied electromagnetic field vibrates polar molecules (usually water) and ions within the food material causing volumetric heating.  RF processing can be effectively used to reduce the come-up time (the time for the coldest spot in the food to reach the desired temperature) due to its larger penetration depth.  Validation of this novel thermal processing method has some unique challenges such as identification of cold spots and temperature measurements, when compared to traditional thermal processing methods.  Validation of RF processing for pathogen reduction requires following steps. First, thermal inactivation kinetics of pathogens in food product are first determined.   Using the dielectric and thermo-physical properties of food products, multiphysics models can be used to optimize electrode and package shape for uniform heating.  Multiphysics models are then used to determine the cold spot locations. Fiberoptic sensors are used to verify cold spot locations using experiments.  Food quality is then evaluated at multiple time-temperature combinations that achieved desired pasteurization levels.  Finally, microbial challenge studies are performed at the final time-temperature combination that provided the highest food quality. Pasteurization of egg white powder and wheat flour using RF processing will be presented as case studies.