Dielectric Properties of Chicken Eggs and Their Components

Abstract

A 2005 USDA-FSIS Risk Assessment reported that approximately 130,000 illnesses occur every year from Salmonella enteritidis (SE) in shell eggs. This foodborne pathogen can be removed by heating. Hot water and humid air processes are currently used to pasteurize a limited number of shell eggs. However, these systems are inefficient and costly to operate. A possible alternative is microwave heating. However, microwave processing requires knowledge of dielectric properties: dielectric constant (e') and dielectric loss factor (e''). Thus, a study was undertaken to collect dielectric properties information on shell egg components. In this study, two ages of eggs were tested: fresh and aged. The eggs were separated out by components: thick and thin albumen, mixed albumen, yolk, and shell. The dielectric constant and loss factor were measured for each component over a temperature range of 0C-70C and a frequency span of 300 MHz 3000 MHz. The e' of fresh and aged egg components showed a slight decline (~ 3 units) with increasing frequency across all temperatures. The maximum e' of yolk was the same for both fresh and aged eggs (47 at 0 oC). However, a primary difference observed in e' between fresh and aged eggs was the fresh yolk had a 30% lower value (23) compared to aged yolk (33) over the temperature range of 10-60 oC. The e'' yolk and albumen components were very much frequency dependent showing exponential decreases of 10-30 units between 300 MHz and 1800 MHz and slight decreases or constant values between 1800 MHz to 3000 MHz.