Foaming, gelling and rheological properties of egg albumen as affected by the housing system and the age of laying hens

The aim of this work was to study the foaming, gelling and rheological properties of albumen as simultaneously affected by the housing system (i.e. conventional cage, organic, and barn) and the age of layers (27, 30, 35, 43, 53, and 68 weeks). Significant effects of the two considered factors and of their interactions were found for almost all the studied properties. In particular, with the increasing of the hen age, a loss in albumen consistency and a weakening of the albumen gel structure were observed. As regards the housing system, differences observed, even if statistically significant, were little and unlikely to have a real effect on technological performances of the eggs when used as food ingredients. Significant correlations amongst technological properties of albumen and its pH and protein content were also found.