Internal and external egg quality responses to egg washing and storage temperature over 42 days

This study investigated how storage temperature and egg washing influence the internal and external quality of eggs during a 42-day storage period. The study aimed to determine whether modest temperature differences within the 15–20 ℃ range, typical of distribution environments, accelerate freshness loss and whether sodium hypochlorite washing alters egg quality decline. A total of 1,560 freshly laid eggs from 62-week-old Hy-Line Brown hens were assigned to a 2 × 3 factorial arrangement comprising two washing treatments (washed vs. unwashed) and three storage temperatures (15, 18, and 20 ℃). Eggs were stored for 42 days, and internal and external quality traits were evaluated. Data were analyzed using two-way ANOVA to determine main and interaction effects. Orthogonal polynomial contrasts were used to evaluate the significance of linear or quadratic effects of the increasing storage temperature. Eggs held at 20 ℃ consistently showed greater weight loss, lower specific gravity, enlarged air cells, elevated albumen pH, and marked reductions in albumen height and Haugh unit compared with those stored at 15 ℃ (p < 0.05). Yolk index values declined more rapidly at higher temperatures. Washed eggs stored at 20 ℃ showed lower albumen height and Haugh unit on day 3, and higher albumen pH early in storage (p < 0.05). However, washing did not influence long-term deterioration. Across treatments, albumen pH increased progressively, paralleled by thinning of the thick albumen and a reduction in Haugh unit, whereas yolk index declined as storage progressed. Within the 15–20 ℃ interval, storage temperature was more consistently associated with the rate and extent of egg quality deterioration than sodium hypochlorite washing, whereas washing related effects were mainly observed during the early storage period. Maintaining storage temperature at or below 18 ℃ may help preserve albumen structure, yolk integrity, and freshness during extended storage.