Date of this Version
Lau, S.K. (2015). Simulation and Validation of Radio Frequency Heating of Shell Eggs (M.S. thesis).
Finite element models were developed with the purpose of finding an optimal radio frequency (RF) heating setup for pasteurizing shell eggs. Material properties of the yolk, albumen, and shell were measured and fitted into equations that were used as inputs for the model. When the egg was heated by itself, heating tend to be focused at the air cell to result in a “coagulation ring.” The focused heating near the air cell of the egg prevented satisfactory pasteurization of the egg, but deeper analysis of the simulation results offered a new perspective on how non-uniform RF heating could occur in heterogeneous food products, especially those that contain air bubbles. By immersing the egg in deionized water, the “coagulation ring” disappeared and heating was concentrated in the yolk after RF heating. Extrapolation of the model suggested that 3 log reductions of Salmonella can be achieved within 37 min of RF heating followed by hot water immersion. In addition, the contamination of the water surrounding the egg was shown to have a positive impact on the heating rate up to a threshold, at which point further contamination decreased the effectiveness of the process. The knowledge gained in this study could be used to design pasteurization equipment for shell eggs that are faster than conventional equipment.
Advisor: Jeyamkondan Subbiah