Wash fresh eggs with a stiff brush and drain. Soak eggs 1 h in 70% ethanol. Drain ethanol. Crack eggs aseptically and discard whites. Remove egg yolks with sterile syringe or wide-mouth pipet. Place yolks in sterile container and mix aseptically with equal volume of sterile 0.85% saline. Store at 4°C until use. Egg yolk emulsion (50%) is available commercially.
Original Source: Bacteriological Analytical Manual, 8th Edition, Revision A, 1998.