Final answer:
Emulsifiers enable water and oil to mix, creating an emulsion with examples including mayonnaise and milk.
Step-by-step explanation:
Emulsifiers are substances that allow for the mixing of water and oil to form an emulsion. In an emulsion, one liquid (typically an oil) is dispersed in another liquid (such as water) in which it is not miscible. This dispersion creates droplets of one liquid within the other.
Many household and culinary products are emulsions, for example, mayonnaise is an emulsion of oil in vinegar stabilized by lecithins in egg yolk. Another example is milk, an emulsion of butterfat in water stabilized by the protein casein. Emulsifiers are also important in digestion, as compounds such as bile help to emulsify fats, increasing the surface area for enzymatic action.