Preparation of Cooked Egg White, Egg Yolk, and Whole Egg Gels for Scanning Electron Microscopy

Cooked egg white, egg yolk, and whole egg gels, fixed with glutaraldehyde or unfixed, were frozen at ‐ 35°C or at ‐ 95°C and freeze‐dried. Alternatively, unfrozen gels fixed with glutaraldehyde, os‐mium‐thiocarbohydrazide‐osmium, or osmium‐tannic acid‐uranyl acetate were dehydrated in ethanol and critical point‐dried from carbon dioxide. Egg yolk and whole egg gels were defatted. Freeze‐dried and critical point‐dried gels were examined by scanning electron microscopy. Freezing and freeze‐drying introduced artifacts due to ice crystal damage, with egg white gels distorted most, and egg yolk gels distorted least. Gels fixed only by glutaraldehyde shrank by 50% during critical point drying. Further fixation by osmium tetroxide and uranyl acetate stabilized gels against shrinkage. Removal of fat from egg yolk and whole egg was essential for observation of protein matrices.