Effects of storage and cooking on the antioxidant capacity of laying hen eggs

The aromatic amino acids and carotenoids are the major contributors to the antioxidant properties of egg yolk. This study aimed to evaluate the effect of simulated retail storage and domestic cooking on the antioxidant activity as well as on the aromatic amino acid and carotenoid contents in ordinary table eggs, omega 3/lutein (n-3/lutein) enriched eggs, and eggs from heritage chicken breeds. The oxygen radical scavenging capacity (ORAC) was the highest in n-3/lutein enriched eggs (161.4 μmol TE/g sample), while eggs from heritage white leghorns (HW) showed the lowest levels (127.6 μmol TE/g sample). Six weeks of storage at refrigerated temperature did not change the ORAC values, as well as the contents of free amino acid, carotenoid, and malondialdehyde (MDA) in egg yolk. Boiling and frying however, significantly reduced the ORAC value, and the contents of free amino acid, lutein and zeaxanthin, and increased the MDA content in eggs. Our results showed that the antioxidant activity is stable during six weeks of simulated retail storage.