Hot Beverage Technology
Coffee Puck
Term from the vending glossary
A compressed disc of spent coffee grounds ejected from the brew group after brewing. A proper puck (uniform, 6–7 g residual moisture) indicates optimal extraction; overly wet or crumbly appearance suggests grinding or dosing problems.
The coffee puck is the compressed cake of exhausted grounds that the brew group ejects into the grounds container after each cup. Its condition is the simplest indicator of a properly functioning machine: uniformly formed and dry indicates that water and grounds are correctly matched.
For operations, the spent grounds present a capacity issue. The container fills proportionally with each cup dispensed, and a full container will shut down the machine — at unmanned locations, this is the most common cause of preventable downtime. Therefore, grounds container capacity should be calculated alongside bean hopper size.