PHYSICAL, CHEMICAL, FUNCTIONAL AND MICROSTRUCTURAL CHARACTERISTICS OF EGG YOLK CONTAINING SALT OR SUGAR.

摘要

The microstructure of processed and unprocessed liquid egg yolk was investigated by scanning electron microscopy. Preparation of the liquid egg yolk by chemical fixation, ethanol dehydration and critical point drying, followed by insertion of a needle to expose the interior of the drop resulted in an osmium tetroxide-penetrated area of microstructure which was of acceptable quality for study. Artifacts, such as destabilized lipid material, ice crystals and shrunken areas, were observed when liquid yolk was not appropriately prepared.Pasteurization of 10% salted liquid yolk at 65Polyacrylamide gel electrophoresis and laser scanning densitometric tracing permitted separation of native egg yolk into 24 bands including flavoprotein. Although peak size and extent of diffusion of bands on electrophoretograms indicated changes in most of the proteins, except phosvitin, mobility of bands did not change due to salt or sugar addition. Salted or sugared (10%) egg yolk proteins are affected by freezing, heating, dehydration, and pH depending on the ionic effect of salt and hydrophilic effect of sugar.The microstructure of liquid yolk was affected by pH, addition of egg white, salt or sugar, freezing, manual homogenization, blending, and dehydration. These treatments resulted in destruction of spheres or granules and alteration of the continuous background.