Why is the top of my coffee covered with a foam layer?
The foam layer covering the espresso and lungo beverages is called "créma" and is the result of thorough extraction of the coffee contained in the capsule by hot water delivered at elevated pressure. Créma is a widely recognized sign of high quality coffee. Consumers can easily test the cream strength by smoothly depositing granular sugar on the créma layer. If créma is good, sugar will take several seconds before sinking under the créma layer.