Development and Validation of a Finite Element Heat Transfer Model for Pasteurization of Shell Eggs with Radio Frequency Heating

Introduction:  Salmonella Enteritidis outbreaks have been associated with shell egg contamination. Recipes that call for the use of raw shell eggs and the consumption of undercooked shell eggs are potential risk factors for salmonellosis. Current methods for pasteurizing shell eggs either take too long or induce albumen coagulation.

Purpose:  Evaluate the feasibility of using radio frequency (RF) heating to pasteurize shell eggs through a computer simulation and subsequently a validation study.

Methods:  Computer simulations of RF heating of shell eggs at different positions were performed using the finite element method in COMSOL Multiphysics. The process time and temperature distributions from the simulations were analyzed with curves plotted using D-values obtained from literature to acquire theoretical log reductions of Salmonella Enteritidis. The simulations were then validated with a Strayfield 6kW radio frequency heater and microbiological studies.

Results:  Computer simulations have shown theoretical reductions of 6 and 8 log of Salmonella Enteritidis in egg yolk and albumen, respectively, with a process time of 7 min. Validation studies are being performed, but preliminary results showed negligible coagulation of albumen. Observed temperature agreed well with predictions of the heat transfer model.

Significance:  When compared to hot water treatment, RF processing significantly reduced the come-up time. With a faster process time and significant reductions of Salmonella Enteritidis, RF heating would allow production of pasteurized shell eggs and reduce the risk of salmonellosis.