Dielectric Properties and Heating Rates of Egg Components Associated with Radio Frequency and Microwave Pasteurization.

Salmonella spp. outbreaks associated with eggs have attracted widespread concerns about food safety. To provide necessary information for further pasteurization processes and computer simulations induced by radio frequency (RF) and microwave (MW) energy, the dielectric properties, penetration depth, and heating rates of egg white, yolk, and eggshell were measured, calculated, or fitted by regression models. The results demonstrated that both the dielectric constant and dielectric loss factor of egg white and yolk decreased dramatically with raised frequency within the RF range from 10 to 300 MHz, and then reduced slightly within the MW range from 300 to 3000 MHz. Dielectric constant, and loss factor of egg white, yolk, and eggshell increased with raised temperature. The penetration depth of egg white, yolk, and eggshell decreased with increasing of frequency. RF waves had a deeper penetration depth than that of MW waves at the same temperature. The fourth-order polynomial models provided a good fit to the experimental data with large coefficients of determination (R2 > 0.902). The heating rate of the egg samples increased with increasing RF voltage and microwave power, and the heating rate of yolk was higher than that of egg white or eggshell at the same conditions. This study offers essential data and effective guidance in developing and optimizing RF and MW pasteurization techniques for ensuring the microbial safety of eggs, using both experiments and mathematical simulations.