Evaluation of Mechanical and Barrier Properties of Protein Coatings on Shell Eggs

Abstract

Development of a coating material for shell eggs is important because of economic loss from shell damage and decline in interior egg quality. Studies were done to evaluate the interior quality (moisture loss, Haugh unit, and pH) and shell properties (strength, thickness, morphology, and color) of uncoated eggs and eggs coated with mineral oil or with solutions of egg albumen, soy protein isolate, wheat gluten, or corn zein. Coated shell eggs were evaluated during 1, 3, 5, 7, 10, 14, 21, and 28 d of storage at room temperature. Eggshells coated with corn zein solution exhibited the least moisture loss and the strongest shell strength. Light microscopy depicted a more compact structure of eggshells coated with corn zein solution. Shell eggs coated with corn zein exhibited the lowest moisture loss and maintained a higher Haugh unit than eggs coated with other treatments. Results also indicated that the protein-based coatings, corn zein and wheat gluten, added strength to the shell, which, in turn, served as a protective barrier.