
Egg is an animal product, most often the egg of the domestic chicken, comprising a shell enclosing the egg white (albumen) and the fat-rich yolk.
The white carries almost no flavour or aroma, adding silky texture rather than taste; the yolk is mildly rich and fatty on the palate.
A single white lends foam and a silky mouthfeel to sour-style drinks, while a whole egg or yolk builds the rich body of flip-style drinks; either is dry-shaken without ice to build the foam, then shaken again with ice to chill and dilute.
Depends on the component: an egg white used for a foam accent can be approximated by another whippable protein such as aquafaba, which forms a comparable protein foam, but a yolk or whole egg used for fat-driven emulsification and richness has no true non-fat replacement, since that animal-protein texture is the point.
Egg white only
Egg white contributes protein foam and a silky texture with negligible fat, whereas whole egg and yolk add fat, emulsification and creamy richness. Both are often written simply as 'egg' in recipes, but they produce different textures and are not interchangeable.
Sourced from the domestic hen, an egg is used in drinks as the whole egg, as egg white only, or as egg yolk only, each serving a different function. The white is largely water and dissolved proteins that whip into a stable foam as agitation denatures them and traps air, while the yolk holds most of the fat and protein and supplies lecithin, a phospholipid that emulsifies.
Raw egg is perishable and carries a food-safety risk such as Salmonella when used uncooked; keep refrigerated and use fresh.