Application of Eggshell-Derived Calcium Carbonate in Chitosan-Based Coating to Extend Fresh Egg Shelf Life

Eggshell waste, comprising approximately 9–15% of total egg mass, is a calcium carbonate (CaCO₃)-rich byproduct frequently disposed of. This study investigates its utilization as a functional additive in chitosan-based edible coatings to enhance egg preservation. Calcium carbonate was extracted from eggshells using oxalic acid and incorporated into 1% (w/v) chitosan solutions at 0.1% and 0.2% (w/v) concentrations. Four treatments were tested: uncoated control, chitosan only, and chitosan combined with CaCO₃ extract at 1% and 2% concentrations. Eggs were coated by immersion for two minutes and stored at room temperature for six weeks. Quality parameters such as weight loss, albumen index, yolk index, and Haugh Unit (HU) were measured weekly. The results showed that chitosan and chitosan CaCO₃ coatings effectively reduced egg quality degradation compared to uncoated eggs. Uncoated eggs remained acceptable for two weeks, while coated eggs maintained quality for up to five weeks, though HU values declined to category B by week six. The addition of CaCO₃ did not significantly improve protection beyond chitosan alone. This study demonstrates the potential of eggshell waste valorization in edible coatings and provides scientific insight for further optimization to enhance food preservation and waste reduction.