The Ultrastructure and the Composition of Separated Fluid of Boiled and then Frozen Egg Albumen

Abstract

The ultrastructure of albumen of fresh chicken and duck shell eggs that were boiled at 100°C or 70°C for 30min and then frozen and thawed, was studied by the use of a TE microscope operated at 80kV. The fluid separated from thawed albumen was collected by draining and centrifugation (2850×G, 20min)of the albumen, and nitrogen and sugars of the fluid were analyzed. After ovomucin was removed from fresh albumen by dilution(1:4)or with 1N HCl(pH5.50), the effects of heat ing and freezing on the ultrastructure of modified chicken and duck albumen were studied by the same method described above. Differences between the micrographs of fresh chicken and duck albumen were evident, but fibrous structures of heavy electron density were occasionally observed in both of them. The fibrous structure was not found in chicken and duck albumen from which ovomucin was removed. Protein matrix of albumen without ovomucin might be easily condensed into clumps or clusters in heating and freezing and when ovomucin was removed with acid, distinct condensation was caused and electron dense spheres were formed. The condensed spheres in chicken albumen were larger than those in duck albumen and protein matrix almost disappeared in chicken albumen, heated at 100°C for 30min. The fluid separated from chicken albumen heated at 70°C, contained much protein, whereas in the fluid of duck heated at 70°C, most of nitrogen was in non-protein type. Paper chromatograms showed that free sugars in the chicken and duck fluid were qualitatively different from the dialyzable sugars of fresh chicken albumen, reported previously. Hexosamine and uronic acid in duck fluid were more than those in chicken fluid.