What is the main composition of crema in espresso?

Crema in espresso is primarily composed of an emulsion of coffee oils, water, and air that forms during the brewing process. This creates a rich, flavorful foam that sits atop a well-pulled shot of espresso. The formation of crema is a crucial indicator of the espresso’s freshness and quality, as it contains aromatic compounds and contributes significantly to the overall flavor profile.

While milk does play a role in other coffee beverages, such as lattes or cappuccinos, it is not involved in the composition of crema. Similarly, mixtures like espresso with chocolate or steamed milk do not represent what crema is, as those are entirely different elements added to espresso drinks rather than components of the crema itself. Thus, the answer highlighting crema as an emulsion of coffee grounds and water accurately captures the essence of what crema is in the context of espresso.