What is an emulsion in cooking?
An emulsion is a smooth mixture of two liquids that normally do not blend, like oil and water, held together by an emulsifier such as egg yolk or mustard.
Why it works
Oil and water repel each other, so they separate if left alone. Whisking breaks the oil into tiny droplets, and an emulsifier like lecithin in egg yolk or mustard coats each droplet so it cannot rejoin. Add oil slowly so each drop gets coated. Too much heat or too much oil at once breaks the sauce into greasy puddles.
How to do it
Common mistakes
- Adding oil too fast, which overwhelms the emulsifier and breaks the sauce.
- Overheating a warm emulsion, which curdles the eggs and separates the fat.
- Skipping the emulsifier, so the mixture splits within minutes.
Questions about emulsion
How do you emulsify a sauce?
Whisk the fat in slowly while the mixture has an emulsifier like mustard, egg yolk, or starch. Keep whisking until the sauce looks thick and glossy.
Why did my sauce break?
The fat was added too fast or the sauce got too hot. Whisk the broken sauce slowly into a little water or a fresh yolk to bring it back.
What are common emulsions?
Mayonnaise, vinaigrette, hollandaise, butter sauces, and milk are all emulsions. Each one uses a different emulsifier.
Olive oil
Mustard
Egg
Lemon
