Emulsifying

Emulsifying is the process of combining two liquids that by nature do not mix (most typically fat and water) into a single stable, uniform mixture called an emulsion. This technique underlies many sauces, dressings, and creams.

The principle is to break one liquid into microscopic droplets and evenly distribute them in the other, keeping them from merging again and separating. For this mechanical force is used — vigorous whisking with a whisk, blender, or shaker. But whisking alone is often not enough: for the emulsion to be stable and not “split” back into oil and water, an emulsifier is needed — a substance that stabilises the boundary between the two liquids. Natural emulsifiers are egg yolk (lecithin), mustard, honey, and some proteins. Classic examples of emulsions are mayonnaise (oil in egg yolk), hollandaise sauce, vinaigrette dressing, cream sauces, and buttercream. The ability to create and hold a stable emulsion is an important culinary skill, since it is emulsifying that gives sauces that inimitable creamy, silky, coating texture. It is an elegant example of how physics and chemistry work for flavour in every kitchen.