
Egg yolk is the yellow, fat- and protein-rich inner portion of a bird's egg, separated from the surrounding white.
Little aroma of its own — faintly savoury at most; the yolk reads as rich, fatty and mild, with a smooth, coating weight rather than a distinct flavour.
Used for richness, emulsification and thickening rather than foam, it must be broken up and fully integrated by vigorous shaking or blending or it will not homogenise. A single yolk enriches and thickens the build, lending a silky, custard-like body.
Where the yolk is a small enriching accent it can be dropped or approximated with cream or an added emulsifier to partly rebuild the viscosity; where a drink is built around a raw, emulsified rich body with no added flavour, no non-egg substitute reproduces the emulsification and neutral richness at once.
Egg white (albumen) is mostly water and protein and whips into a stable foam, contributing dry aeration and a frothy cap with little richness; egg yolk is fat- and protein-rich, does not foam, and contributes body, richness and emulsification. Whole egg combines both.
The central golden fraction of a hen's egg, separated from the white, it is an emulsion of water, lipids and protein carrying far more fat and protein than the albumen. Its lecithin content makes it a natural emulsifier that binds fat and water; unlike the white, it will not whip into a stable foam.
A highly perishable raw animal product; separate it fresh, keep it cold, and observe the usual raw-egg safety considerations.