What is real mayonnaise made out of?

November 12, 2025 •

4 min read

According to the U.S. Food and Drug Administration, a product can only be labeled as "mayonnaise" if it contains a minimum of 65% vegetable oil by weight. This legal definition highlights that true or real mayonnaise is fundamentally an emulsified sauce created from a simple yet precise combination of oil, egg yolk, and an acidic liquid.

Quick Summary

An emulsion of oil, egg yolk, and an acid like vinegar or lemon juice is what constitutes real mayonnaise, with egg yolk serving as the key emulsifier for its creamy texture.

Key Points

Core Ingredients: Real mayonnaise is an emulsion of oil, egg yolk, and an acidic liquid like vinegar or lemon juice.
Emulsifier's Role: Egg yolk contains lecithin, a natural emulsifier that prevents the oil and water-based components from separating.
Oil Type Matters: Neutral oils like canola or avocado oil are preferred for a mild flavor, as extra-virgin olive oil can cause bitterness when blended.
Dressing vs. Mayo: Mayonnaise-type dressings have lower oil content and often use added stabilizers and sweeteners, tasting tangier and sweeter than real mayonnaise.
Technique is Key: For homemade mayo, adding the oil in a very slow stream while constantly mixing is critical for a stable, creamy emulsion.

The Three Essential Ingredients of Real Mayonnaise

At its core, real mayonnaise is an oil-in-water emulsion that relies on three primary components to achieve its distinctive creamy texture. The careful and precise combination of these ingredients, often at room temperature, is the secret behind its smooth, stable consistency.

1. Oil: The Primary Foundation

Oil is the main ingredient by volume and weight in mayonnaise, typically making up at least 65% of the finished product in commercial varieties. The type of oil used can significantly impact the flavor profile. Neutral-flavored vegetable oils, such as canola, sunflower, or avocado oil, are common choices for their mild taste. Stronger-flavored oils, like extra-virgin olive oil, are often avoided or used in small amounts for fear of becoming bitter when blended vigorously. The oil is what provides the richness and body, with smaller oil droplets leading to a whiter color and thicker texture.

2. Egg Yolk: The Master Emulsifier

Egg yolk is the hero of real mayonnaise. It contains lecithin, a fat emulsifier that is essential for binding together the immiscible liquids of oil and water. Lecithin molecules have a water-attracting (hydrophilic) head and an oil-attracting (hydrophobic) tail, allowing them to form a stable bridge between the two liquids. When the oil is slowly drizzled into the egg yolk and acid mixture while whisking, the lecithin in the yolk surrounds each tiny oil droplet, preventing them from coalescing and separating. This process is what creates the permanent emulsion that gives mayonnaise its creamy, stable structure.

3. Acid: The Flavor and Stabilizer

The acidic component in mayonnaise, typically vinegar or lemon juice, serves a dual purpose. First, it provides the tangy flavor that balances the richness of the oil. Different vinegars, such as white wine vinegar or apple cider vinegar, can slightly alter the final taste. Second, the acid helps stabilize the emulsion. The low pH level strengthens the proteins in the egg yolk, further securing the binding of the oil droplets. This low pH also acts as a natural preservative, inhibiting bacterial growth and extending the shelf life of commercial mayonnaise.

Optional Add-Ins and Variations

While oil, egg yolk, and acid are the foundational trio, other ingredients are often included to enhance flavor and texture. These can vary widely depending on the recipe and regional preferences.

Mustard: Dijon or mustard powder is a common addition. It provides a subtle, pungent flavor and contains its own emulsifying agents, which further stabilize the mixture.
Salt: A critical seasoning that brings out the flavors of the other ingredients.
Sugar: A touch of sugar is sometimes added to balance the sharpness of the acidic component.
Spices and Herbs: Many recipes incorporate spices like paprika, white pepper, or garlic for additional depth. Aioli, for example, is a garlic-infused mayonnaise.

Real Mayonnaise vs. Mayonnaise-Type Dressing

Not all creamy spreads are created equal. Legal standards dictate the difference, with real mayonnaise having a significantly higher oil and egg content.


Feature	Real Mayonnaise	Mayonnaise-Type Dressing (e.g., Miracle Whip)
Oil Content	Min. 65% by weight (U.S.)	Min. 30% by weight (U.S.)
Emulsifier	Primarily egg yolk	Egg yolk and other thickeners like starches
Flavor Profile	Rich and tangy	Sweeter and spicier
Texture	Thick, creamy, and smooth	Thinner or more gel-like due to stabilizers
Additives	Generally minimal in homemade versions	Often includes high fructose corn syrup and modified food starches

Making Homemade Mayonnaise: The Technique

Creating real mayonnaise at home is a simple process, but it requires patience to succeed. The key is to add the oil very slowly to create a stable emulsion.

Gather Ingredients: Ensure all ingredients, especially the egg, are at room temperature to aid emulsification.
Combine Base: In a food processor, blender, or mixing bowl, combine the egg yolk(s) with the acid and any optional flavorings like mustard and salt.
Slowly Add Oil: While the machine is running (or while whisking vigorously by hand), begin adding the oil a few drops at a time. A very thin, steady stream is crucial. Adding the oil too quickly will cause the emulsion to break, resulting in a separated, oily mess.
Thicken and Finish: As more oil is added, the mixture will thicken and turn opaque. Once all the oil is incorporated, continue blending for a few seconds until thick and silky. Taste and adjust seasonings as needed.

Conclusion

Understanding what is real mayonnaise made out of reveals a fascinating blend of culinary art and food science. From the indispensable emulsifying power of the egg yolk to the high percentage of oil and the balancing tang of acid, the classic recipe is a testament to the transformative power of simple ingredients. The next time you enjoy this popular condiment, you can appreciate the elegant chemical process that brings its creamy richness to life.

Frequently Asked Questions

Store-bought mayonnaise is made with pasteurized eggs, which eliminates the risk of salmonella. If you make homemade mayonnaise, using pasteurized eggs or starting with eggs from a trusted source is recommended, and it should be consumed within a few days.

While mayonnaise and aioli both use the principle of emulsification, aioli is traditionally a garlic-based emulsion from the Mediterranean region that sometimes, but not always, uses eggs. Modern culinary practice often refers to any flavored mayonnaise as an aioli.

Yes, you can use regular or light-tasting olive oil for mayonnaise. However, extra-virgin olive oil has a strong flavor that can become bitter when whipped, so it's generally best to use a more neutral-flavored oil or a blend.

If mayonnaise breaks and separates, the emulsion has failed. It can often be fixed by starting over with a new egg yolk (or a teaspoon of mustard) in a clean bowl and slowly whisking the broken mixture into the new base.

Yes, vegan mayonnaise exists and typically uses plant-based proteins, such as soy or pea protein, to create the emulsification and creamy texture. Legally, these products are not labeled as 'mayonnaise' in the U.S., but as 'dressing' or 'spread'.

Mayonnaise is a calorie-dense food due to its high oil content, but it consists mainly of unsaturated fats, which can be part of a balanced diet when consumed in moderation. Making it with healthier oils like avocado oil can also improve its nutritional profile.

The acid, such as vinegar or lemon juice, serves two main functions: it provides a tangy flavor to balance the richness of the oil and helps to stabilize the emulsion, which also aids in preservation.