An emulsion is a mixture of two liquids that usually don’t mix—like oil and water. Emulsifying is the process where they blend and become uniform. Understanding the science behind that can greatly improve your sauces and more!
What are emulsifiers?
An emulsifier is a molecule that stabilizes emulsions by reducing the natural tension between the two incompatible liquids. A little science behind how they work:
- They are amphiphilic, which means that they have 2 ends, a hydrophilic (water-loving) and hydrophobic (water-fearing and prefers oil). Basically a bridge to connect the 2 substances that wouldn’t normally mix.
- They also reduce surface tension between water and oil (thats why they form separate layers) to make it easier for oil droplets to disperse in water (or the reverse).
- Once dispersed, emulsifiers surround those droplets and form a protective layer. This prevents droplets from merging with each other and forming a separation again. (eg. vinegar in olive oil)
Stabilising emulsions
Acids lower the pH of a mixture. This affects the electrical charge on the emulsifier to make them more surface-active, meaning they better adsorb at the oil-water interface and stabilize droplets.
Acids also have a few additional benefits:
- Adds brightness because emulsions often have a lot of fat that dulls flavour
- Balances the emulsion to cut through the richness and avoid a greasy taste
Using emulsifiers
Now that we know how emulsifiers work, here are common ones that we can use in cooking:
- Lecithin – found in egg yolks (read more in my article on eggs)
- Mustard – contains natural emulsifiers
- Honey and garlic – can help stabilize vinaigrettes
Applying emulsification in the kitchen
Making Salad Dressings
- Combine oil + vinegar + mustard (or garlic/honey)
- Whisk or shake vigorously to disperse oil droplets
- Add oil slowly while whisking vinegar/mustard to create a stable emulsion
Homemade Mayonnaise
- Use egg yolk (contains lecithin) as the emulsifier
- Slowly add oil while whisking or blending egg yolk and acid (lemon juice or vinegar)
- If you go too fast the emulsion ‘breaks’ (fix it by adding a spoon of water/more yolk)
Creamy Sauces
- Hollandaise, béarnaise, and aioli are all emulsified sauces
- Temperature control is key—heat too much and the emulsion can break
- Gentle whisking + slow addition of fat = success
Ice Cream
Even ice cream involves emulsification! It keeps fat evenly distributed so the texture stays smooth and creamy and not icy.
*Add oil slowly to create smaller droplets because as mentioned, smaller droplets allow emulsifiers to surround it which will lead to a more stable emulsion
Emulsion Troubleshooting
- Broken emulsion-> Slowly whisk it into a new emulsifier base (e.g. more yolk, mustard, or a bit of warm water)
- Too thick-> Add a few drops of water or acid (like lemon juice)
- Too thin-> Slowly add more oil while whisking
Immersion Blender—Do you need one?
An immersion blender (or stick blender) is one of the best tools for making quick and stable emulsions. The blender’s fast-spinning blades shear the oil into tiny droplets while mixing it vigorously, and this helps the emulsifier surround the droplets quickly. It is optimal for a smooth emulsion, but it can be substituted with:
- Whisk and bowl – simplest substitute that works, just add oil slowly and whisk vigorously.
- Jar with a tight lid – for shaking and making thin emulsions.
- Blender or food processor – especially for larger batches or thick sauces.
Hope this article helps you understand how emulsifying works in order to level up your sauces!
