Emulsion Sauces

Emulsion sauces exploit the physics of emulsions to make oil and water coexist as a single, thick, creamy liquid. They divide into three families by temperature and emulsifier: cold egg sauces (mayonnaise), hot egg sauces (hollandaise, béarnaise), and butter sauces (beurre blanc). Each uses a different strategy to coat fat droplets in a water-based continuous phase, and each has a different fragility.

Mayonnaise: the cold emulsion

Mayonnaise is oil dispersed drop by drop into egg yolk and acid — the purest demonstration of emulsion building. The yolk’s phospholipids and proteins coat each oil droplet as it enters, creating a stable oil-in-water emulsion that can reach near-solid thickness.