The effects of edible coatings on chicken egg quality under refrigerated storage

Seventy-three billion chicken eggs are produced annually in the United States. However, less than 0.1% of these eggs are exported. Increasing the shelf-life of eggs may increase export sales. The goal of this research was to determine whether food-grade coatings on eggs may extend shelf-life under refrigerated storage. Four food-grade coatings were selected: paraffin wax, mineral oil, soy protein isolate, and whey protein isolate (WPI). These coatings were applied to fresh chicken eggs. The eggs were stored for 12 wk in refrigerated storage at 7 degrees C. Two replicates of the 12-wk study were conducted. Egg properties measured included Haugh units, albumen pH, yolk pH, albumen CO(2) content, vitelline membrane strength, water loss, shell strength, and shell color. Egg functionality measurements included foam volume, angel food cake volume, and emulsion stability. Statistical analysis was performed using the SAS PROC GLIMMIX method (P < 0.05). Results found that coated eggs maintained higher Haugh units beyond 6 wk compared with the uncoated eggs. Also, coated eggs maintained a higher CO(2) content and lower albumen pH than the uncoated eggs over the storage period. Vitelline membrane strength slightly decreased over time in uncoated eggs, but did not change in coated eggs. Overall, oil-, wax-, and WPI-coated eggs maintained higher vitelline membrane strength (14%) than the uncoated eggs. Coating of chicken eggs with a food-grade film (oil, wax, WPI) will extend shelf-life beyond 6 wk.