What is a substance that allows fats or oils to mix with water called?

The correct answer is an emulsifier. An emulsifier is a substance that helps to stabilize a mixture of two or more immiscible liquids, such as oil and water. Emulsifiers work by reducing the surface tension at the interface between the two liquids, allowing them to blend more easily. This is crucial in food preparation, particularly in the making of dressings, sauces, and many processed foods, where oil and water-based ingredients need to be combined to achieve a uniform texture.

The role of emulsifiers can be seen in products such as mayonnaise or salad dressings, where they help keep the oil droplets dispersed in the water phase. Common emulsifiers include lecithin (found in egg yolks), mustard, and certain food additives.

Other options provide different functions that do not pertain to the mixing of fats and oils with water. Stabilizers help maintain the texture and consistency of emulsified products but do not specifically allow for the mixing process itself. Thickeners serve to increase viscosity in liquids but do not facilitate the blending of immiscible ingredients. Preservatives are used to prolong the shelf life of products by inhibiting microbiological growth or oxidation, which is unrelated to the mixing of fats and water.