What is the role of emulsifiers like egg yolk in mayonnaise?

Emulsifiers, such as egg yolk, play a critical role in mayonnaise by stabilizing the mixture of oil and vinegar (or any other acidic component). Mayonnaise is an emulsion, which is a mixture of two immiscible liquids—oil and water (from vinegar or lemon juice). Without an emulsifier, these two components would separate.

The egg yolk contains phospholipids, particularly lecithin, which have hydrophilic (water-attracting) and hydrophobic (oil-attracting) properties. When whisked into the oil and vinegar, the emulsifier molecules help to create small droplets of oil suspended in the vinegar. This process not only gives mayonnaise its creamy texture but also prevents the oil and vinegar from separating over time, thereby stabilizing the emulsion.

The other answer choices do not accurately describe the primary function of emulsifiers in mayonnaise. While thickeners can be used in some recipes, the emulsifying action is crucial for the formation of the stable emulsion that characterizes mayonnaise. Coloring agents are not the main purpose of egg yolk in this context, as mayonnaise typically relies on the natural color of the ingredients. Finally, eliminating odors is not related to the emulsifying properties of egg yol