Emulsions: mayonnaise, vinaigrette and sauces that don't break
An emulsion is tiny droplets of one liquid dispersed in another it normally won't mix with. Emulsifiers (molecules with a water-loving and a fat-loving end) keep the droplets apart.
Common emulsifiers
- Egg yolk lecithin: mayonnaise, hollandaise, aioli.
- Mustard: mucilage in the seed coat stabilizes vinaigrettes.
- Starch: pasta water helps cheese and fat bind in cacio e pepe.
- Milk proteins: butter sauces, beurre blanc.
Why sauces break
Oil added too fast, too much oil for the emulsifier, or too much heat (yolk proteins tighten above about 70-80°C). To fix mayo: start a fresh yolk (or a spoon of water or mustard) and whisk the broken sauce in drop by drop.
Safety
Raw-egg sauces carry Salmonella risk. Use pasteurized eggs for people who are pregnant, very young, elderly or immunocompromised.
Ask your bot about the science
Explain emulsions in plain English for a home cook, with one kitchen experiment I can do to see it, and how it applies to [dish].
Give temperatures in °F and °C and say if they are approximate.Where these facts come from
- American Chemical Society: Reactions, food chemistry explainers
- Exploratorium: Science of Cooking
- USDA FSIS: Safe temperature chart
- FoodSafety.gov: Safe minimum internal temperatures
- Harold McGee, On Food and Cooking (Scribner, 2004): the standard reference on kitchen chemistry
Checked Oct 29, 2026. Temperatures given for reactions are typical ranges, not sharp switches; they shift with moisture, pH and time. Food-safety numbers always come from USDA/FoodSafety.gov.
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