What is the binding agent in mayonnaise?

The binding agent in mayonnaise is egg yolks. Egg yolks contain emulsifiers, particularly lecithin, which help to blend oil and water-based ingredients together, creating a stable emulsion. When you whisk egg yolks with oil and other ingredients, the lecithin molecules push the oil droplets apart and suspend them in the mixture. This prevents the oil from separating, resulting in the creamy texture characteristic of mayonnaise.

While mustard, vinegar, and olive oil are important components in making mayonnaise, they do not serve as the binding agent. Mustard can enhance flavor and also assist with emulsification, and vinegar adds acidity and flavor, but it is the egg yolks that are essential for achieving the stable mixture. Olive oil is a primary fat used in mayonnaise, contributing to its richness, but on its own, it cannot bind the emulsion without the presence of egg yolks.