What is a primary characteristic of crema?

Crema is the golden, foamy layer that forms on top of a freshly brewed espresso shot. Its primary characteristic is that it enhances coffee flavors. The presence of crema is indicative of the quality of the espresso, as it helps to lock in flavors and aromas released from the coffee oils and compounds during the brewing process. This rich layer contributes to the overall taste experience, making the coffee not only more flavorful but also more aromatic.

While some of the other options mention aspects related to crema, they do not capture its essential function and purpose as effectively. For example, although crema does contain some air and contributes to the perception of a coffee's body, its main role is to enhance the intrinsic flavors of the espresso, ensuring a complete and enjoyable tasting experience.