Whipping and gelling properties of egg as affected by compositional variability

Many are the natural factors affecting whipping and gelling properties of egg and egg fractions. The effects of these factors are basically referable to egg composition changes, especially in terms of quantity and quality of the functional elements (i.e. proteins), and of the physico-chemical properties of the medium (such as pH and ionic strength). Aim of the work was to study the whipping properties of albumen and the gelling properties of both albumen and whole egg in dependence of natural compositional variability or of deliberately altered egg composition (unnatural albumen to yolk ratio), resulting from different hen age or rearing system. A reduction of the albumen to yolk ratio as well as a reduction of proteins in the albumen fraction, as a function of increasing hen age, were observed. Both gel consistency and water holding capacity resulted highly correlated (p<0.001) with albumen pH, naturally ranging between 8.61 and 9.06, and protein content. In the small range of natural variability of albumen protein content (about 9.8-11.4 g/100g), no significant influence of total protein was observed on overrun values, and foam consistency and instability. However overrun resulted highly correlated (p<0.001) with albumen gelation temperature, thus indicating a specific dependence of this property on the quality of albumen proteins.