The Effect of Egg Cuticle Thickness on Physical Egg Quality Traits at Different Storage Durations and Conditions

ABSTRACT This study investigated the effect of cuticle thickness on quality traits of eggs stored at different conditions for varying durations. Eggs were obtained from Lohmann LSL Classic layer chicken hybrids housed in enriched cage system. 450 eggs were analyzed, 90 eggs at each storage period; 0, 14, and 28 days (d) at ~4 °C and ~24 °C, respectively. Additionally, after 0, 14, and 28 d of storage, eggs were stained with a 1% aqueous solution of Edicol Supra Pea Green H and Tartrazin. Cuticle thickness was determined using a colorimeter, and then egg quality analyses were performed. The results showed a decrease in egg weight, specific gravity, albumen height, albumen index, Haugh unit, yolk height, yolk index, and yolk color score, and an increase in egg weight loss rate with the increase in storage duration (p<0.05; p<0.01). Eggs stored at room temperature had the lowest weight, specific gravity, albumen height, albumen index, Haugh unit, yolk height, yolk index, and yolk color, and the highest egg weight loss (p<0.05; p<0.01). The opposite was true for fresh and fridge-stored eggs, whose values for most of the traits above were similar. Eggs with thinner cuticle coverage had the lowest weight, albumen height, albumen index, and Haugh unit, and the highest weight loss rate; whereas eggs with a thicker cuticle had the highest weight, albumen height, albumen index, and Haught unit (p<0.05; p<0.01). Specific gravity, yolk height, and yolk index were significantly lower in eggs with thinner cuticle coverage than in those with medium and thicker cuticle coverage; however, shell-breaking strength was significantly higher in eggs with thinner cuticle coverage compared to those with medium and thicker cuticle coverage. It was concluded that prolonged egg storage and storing eggs at room temperature results in a significant decline in the analyzed egg quality traits, with the exception of shape index and shell thickness. Also, as the egg cuticle layer becomes thicker, the rate of weight loss and shell-breaking strength are reduced, while the internal egg quality traits are preserved.