Crema-Formation, Stabilization, and Sensation

The signature of a good quality espresso coffee is a nice dense brown crema layer that covers the liquid extract. Although some work has been done on the mechanism of formation, the molecular science on the stabilization of the crema is still shrouded in mystery. This chapter gives an overview of the mechanisms of formation and some recent data on the compounds in charge of the stabilization. Further to these physical-chemical aspects, an overview of the role the crema plays in the sensorial perception of espresso coffee is given. We end with the conclusion that to further develop products with optimal crema, a holistic approach needs to be considered, taking into account physics, chemistry, sensory, and consumer science.