Factors Affecting the Vitelline Membrane of the Hen’s Egg

Experimentation was conducted to determine the effect of egg size, length of storage, storage temperature, albumen pH and albumen viscosity on the vitelline membrane. The effect of changes in the vitelline membrane on water movement across it from the albumen o t the yolk was also studied. The dry membrane weight decreased as a percentage of dry yolk weight as the egg weight decreased. Vitelline membrane weight increased under refrigerated (7° C.) conditions and decreased at room temperature (22° C). The length of storage from 0–9 days had no effect at 7 or 22° C. on membrane weight, although albumen breakdown occurred as evidenced by increased pH. Albumen pH affected the membrane weight only at 22° C. The membrane weight decrease at 22° C. was paralleled by a decrease in yolk index. Storing yolks in thick albumen under refrigerated conditions resulted in an increase in membrane weight. Storing in thin albumen produced no change. The increase in weight was thought to be due to the association of the thick albumen with the membrane. The increase in membrane weight did not increase the strength of the vitelline membrane. Movement of water into the yolk was decreased when membrane weight increased.