Traditional aioli and mayonnaise are both emulsions, but they do not rely on exactly the same ingredients to stabilize oil. Traditional aioli can be made with garlic, oil, and salt, while mayonnaise uses egg yolk, oil, and an acidic aqueous phase such as vinegar or lemon juice.
Confusion comes from the modern practice of calling garlic-flavored mayonnaise “aioli.” That sauce can be excellent, but its emulsion is fundamentally supported by mayonnaise chemistry.
What is an emulsion?
Oil and water do not remain mixed spontaneously. In an emulsion, one phase is broken into tiny droplets dispersed through the other. To stop those droplets from rapidly merging again, surface-active compounds need to sit at the oil-water interface.
Whisking, grinding, or blending creates small droplets; emulsifiers help keep them separated.
Mayonnaise relies primarily on egg yolk
Egg yolk contains phospholipids, lipoproteins, and other compounds with regions that interact with both water and fat. This allows them to coat and stabilize oil droplets.
That is why an unexpectedly large amount of oil can be incorporated while the mixture remains semisolid. Food-science reviews describe traditional mayonnaise as an oil-in-water emulsion containing roughly 70–80% fat.
Traditional aioli shows that garlic can help emulsify too
A study specifically examining garlic aqueous extract found proteins and saponins with emulsifying ability. The researchers also note traditional Spanish alioli as a sauce made primarily from olive oil, garlic, and salt without egg yolk.
Grinding garlic with salt releases water and soluble compounds from its cells. Slowly adding oil while working that paste creates small droplets that garlic components help stabilize.
That does not mean garlic and yolk work equally well
Egg yolk is a much stronger and more predictable emulsifier, which makes mayonnaise easier to build. Egg-free traditional aioli requires patience, enough garlic relative to oil, and slow oil addition.
Very dry garlic or too little garlic for a large oil volume can give a less stable emulsion. Mortar technique, grinding, and addition rate also matter.
Why do many modern aioli recipes include egg?
Adding egg yolk or whole egg makes the process far more forgiving. An immersion blender can create tiny droplets in seconds while egg emulsifiers stabilize the structure.
This is why garlic mayonnaise has spread so widely under the aioli name. It is fast, creamy, and stable even though it is not the strict traditional formulation.
Acid is not the same thing as an emulsifier
Lemon juice or vinegar adds water, acidity, and flavor. It can also change electrical charge, viscosity, and protein behavior, but acid alone does not replace the emulsifying function of yolk or garlic components.
In mayonnaise, the acidic aqueous phase surrounds dispersed oil droplets. Traditional aioli may contain very little water beyond what comes naturally from garlic.
Why does an emulsion break?
If oil is added faster than the system can divide and stabilize it, droplets collide and merge. Breakage can also occur when there is simply too much oil for the available emulsifier.
A common rescue is to start with a fresh small aqueous/emulsifier base and slowly add the broken sauce as though it were the oil phase.
Which one is more “authentic”?
Aioli has a historical identity built around garlic and oil, while “garlic mayonnaise” more accurately describes egg-based versions. Modern restaurant usage is flexible, however, and “aioli” often refers broadly to flavored mayonnaise sauces.
The practical rule: if the sauce contains yolk, stability comes mainly from egg emulsification; in traditional garlic-and-oil aioli, garlic supplies the components that help stabilize droplets. Both are emulsions, but they are not chemically identical.
For repeatable results, pay attention to the exact product and technique rather than only the recipe name. Variety, grain size, water amount, agitation, and temperature can all substantially change final texture.
For repeatable results, pay attention to the exact product and technique rather than only the recipe name. Variety, grain size, water amount, agitation, and temperature can all substantially change final texture.
For repeatable results, pay attention to the exact product and technique rather than only the recipe name. Variety, grain size, water amount, agitation, and temperature can all substantially change final texture.
Sources
- Food Hydrocolloids — Emulsification properties of garlic aqueous extract — Study showing water-soluble garlic components, including proteins and saponins, can emulsify oil; it specifically discusses traditional Spanish alioli made primarily from olive oil, garlic and salt without egg yolk.
- Trends in Food Science & Technology — Physical and flavour stability of mayonnaise — Review describing traditional mayonnaise as an oil-in-water emulsion of egg, vinegar, oil and spices with roughly 70–80% fat.
- Food Research International — Black garlic particles in mayonnaise — Current food-science description of mayonnaise as a high-internal-phase oil-in-water emulsion in which egg yolk emulsifiers stabilize tightly packed oil droplets.