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Sauces and finishing · intermediate

Emulsification

Also: emulsifying, mounting (monter au beurre)

Combining fat and water-based liquids into a smooth, stable sauce.

286 recipes use it

What it is

Emulsified sauces suspend tiny droplets of one liquid in another: mayonnaise and aioli (oil in water and egg yolk), vinaigrettes, hollandaise, beurre blanc, and many cream- or cashew-based gravies. The technique is to add one phase slowly while whisking or blending hard, usually with an emulsifier present.

Why cooks use it: Emulsions give sauces body, gloss and a rich mouthfeel, and let fat-soluble and water-soluble flavours come together.

The science

Oil and water do not mix. Vigorous whisking breaks oil into small droplets, and emulsifiers such as lecithin in egg yolk or mustard coat the droplets so they do not merge. Too much oil too fast, wrong temperature or too little water lets droplets coalesce and the sauce 'breaks'.

How proteins set when cookedEmulsionsFats and oilsMolecular gastronomyFoams and gels

Step by step

  1. Start with the emulsifier and water-based ingredients (egg yolk, mustard, lemon, a little water) at room temperature.

  2. Add the oil or melted butter drop by drop at first, whisking constantly.

  3. Once the mixture thickens, add the fat in a thin, steady stream.

  4. Thin with a few drops of water or lemon if it becomes too stiff.

  5. For warm butter sauces, keep the sauce warm (roughly 50–65 °C) and away from direct high heat.

Heat and timing

  • Emulsification 50–70 °C · Warm egg-butter sauces: yolks are cooked gently to around 65–70 °C; hold hollandaise and beurre blanc warm, roughly 50–65 °C. Cold sauces at room temperature.

Time: Mayonnaise 3–5 minutes by hand; 30 seconds with a stick blender.

How you know it’s right

  • Sauce thickens and turns opaque and glossy
  • Whisk leaves trails
  • No oily sheen or beads of fat on the surface

Common mistakes

  • Adding oil too fast
  • Cold ingredients straight from the fridge
  • Overheating egg-butter sauces so yolks scramble
  • Letting beurre blanc boil

Troubleshooting

Mayonnaise split
Start a new yolk (or a teaspoon of water or mustard) in a clean bowl and whisk the broken sauce into it drop by drop.
Hollandaise curdling
Take it off the heat and whisk in a spoon of cold water; if broken, rebuild on a fresh yolk.

Restaurant DNA

How professionals do it

Restaurants hold hollandaise and beurre blanc in warm bains-marie or insulated containers through service and finish pan sauces by mounting with cold butter off the heat.

At home

Use a stick blender in a narrow jar for near-foolproof mayonnaise; make warm butter sauces just before serving.

General professional practice — not any particular restaurant’s recipe.

Food safety

  • Raw-egg sauces: use pasteurised eggs for pregnant people, young children, older adults and anyone immunocompromised; keep refrigerated and use within a few days.

Practise it

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