Order aioli anywhere outside Catalonia or Provence and what arrives is mayonnaise seasoned with garlic — same yolk, same oil, same lecithin holding it together. The dish the word actually names is different: raw garlic pounded to a paste and beaten with olive oil until it thickens, with no egg involved at all.
Why traditional allioli holds together without an egg
Mayonnaise has lecithin from an egg yolk doing the work of coating oil droplets so they can't recombine. Allioli has none of that. What it has instead is garlic cell walls, ruptured by a mortar and pestle into a fine, sticky paste, and salt, which pulls moisture out of the ruptured cells to give the paste something to disperse into. Neither is a strong emulsifier next to lecithin. Pounding does most of the real work here, breaking the oil into droplets small enough that the modest surface-active material garlic does carry can coat them before they merge back together.
Why it breaks so much more easily than mayonnaise
An egg yolk can carry a cup or more of oil in suspension, because lecithin coats droplets efficiently and in bulk. Garlic paste can't do that. Push more oil at it than the paste can disperse, and it separates the way any emulsion does once the surfactant runs out — except allioli runs out much sooner. That's why a traditional batch stays small and heavily garlicked relative to how much oil it actually holds. Add oil at the pace you could get away with once mayonnaise has a head start, and allioli breaks in seconds instead of minutes.
Why most "aioli" on menus is just garlic mayonnaise
Put an egg yolk in the bowl and you inherit every advantage mayonnaise has: a base that holds far more oil, comes together in a couple of minutes, and doesn't need a mortar. That's the version behind almost every "aioli" served today, including the ones on this site — whisk mayonnaise with minced garlic, lemon juice, and salt, and it's done. It took the older dish's name because it does the job better for anyone not standing over a mortar in Catalonia.
Mayonnaise-based aioli vs. traditional allioli
| Mayonnaise-based aioli | Traditional allioli | |
|---|---|---|
| Emulsifier | Egg yolk (lecithin) | Garlic paste, dispersed by pounding |
| Egg | Yes | No |
| Oil it can hold | A cup or more per yolk | Far less per amount of garlic |
| How it's made | Whisked in a couple of minutes | Pounded by hand, often 15–20 minutes |
| Texture | Smooth, mild | Thick, sharply garlicky, sometimes grainy |
| What most restaurants serve | This one | Rarely |
Which one to reach for
If a recipe calls for aioli, mayonnaise stirred with garlic and a squeeze of lemon is what almost every kitchen means, this site included, and it holds up fine as a dip, a sandwich spread, or a sauce stirred through a bowl. Reach for real allioli only when the point is the garlic itself — thick enough to coat a spoon, sharp enough that a little goes further than a garlic mayonnaise ever would.
The one real safety line
Garlic held in oil without enough acid or refrigeration is the textbook setup for Clostridium botulinum, which grows without oxygen and produces a toxin with no smell or taste to warn you off. Traditional allioli, made from raw garlic and oil with nothing else added, should go straight into the refrigerator and get used within a few days — not left on the counter the way a bowl of garlic mayonnaise, with its egg and acid, tolerates a little more casually.