Internal quality of commercial eggs subjected to different shell treatments and storage times

Abstract

Five hundred sixty eggs from commercial layers aged 74 weeks were subjected to sanitization and shell-covering procedures. The treatments consisted of two egg sanitization methods, sanitized (S) and not sanitized (NS), and two methods of shell covering, not covered (NC) and covered (C) with whey protein concentrate solution, arranged in a completely randomized design in a 2 × 2 factorial scheme (sanitization × shell coating), with five replications obtained from the average of four eggs evaluated in seven storage periods (1, 7, 14, 21, 28, 35, and 42 days). Albumen pH and yolk lipid oxidation using the TBARS test were evaluated. The averages for each period were submitted to analysis of variance, any differences observed were submitted to the Tukey test (5%), and regression analysis was performed between periods for each method. Using SDS-PAGE, the protein profile of albumen at 1 and 42 days was evaluated descriptively. Using methods S and NS, the pH and TBARS of eggs did not change on any of the days evaluated (P>0.05). Methods C and NC had similar pH values (P>0.05) only when using fresh eggs; however, the pH was higher when using eggs from Method NC (P<0.0001) compared with Method C. For all techniques, the analysis of pH regression between periods revealed quadratic behavior. While regression analysis demonstrated an increasing linear behavior for all methods, the TBARS analysis results for C and NC on all evaluated days were comparable (P>0.05). Whey protein concentrate does not affect the pH of sanitized eggs. The protein profile of the albumen and TBARS values of egg yolks stored at room temperature are unaffected by sanitation and whey protein concentrate covering, and TBARS values increase over storage days in all cases.