Challenges in Radiofrequency Pasteurization of Shell Eggs: Coagulation Rings

Area of Science:

• Food Science
• Electromagnetics
• Thermal Engineering

Background:

• Radiofrequency (RF) heating is explored for food pasteurization.
• Understanding heat distribution in heterogeneous products like eggs is crucial.
• Egg quality is sensitive to localized temperature increases.

Purpose of the Study:

• To simulate RF heating of shell eggs for pasteurization.
• To model temperature-dependent properties of egg components.
• To analyze electric field patterns for non-uniform heating insights.

Main Methods:

• Finite element modeling of 50 RF heating configurations at 27.12 MHz.
• Measurement and fitting of temperature-dependent thermal and dielectric properties.
• Development of a regression equation for electrode voltage and egg positioning.

Main Results:

• Simulations showed good agreement with experimental temperature deviations (RMSE 0.35–0.48 °C).
• A "coagulation ring" formed around the air cell due to localized heating.
• Non-uniform RF heating was observed, impacting pasteurization efficacy.

Conclusions:

• Focused RF heating near the egg's air cell leads to coagulation, hindering pasteurization.
• Analysis of electric fields provides insights into non-uniform heating in complex foods.
• Findings can inform the development of RF pasteurization for eggs and other heterogeneous foods.