What is a guardiola in coffee drying?

A guardiola is a rotating drum mechanical dryer used to reduce moisture in parchment coffee. The drum rotates continuously while heated air circulates through the coffee mass, gradually driving out moisture over roughly three days.

The continuous tumbling gives it an advantage over static silo dryers: every bean gets relatively even exposure to the drying airflow rather than sitting in a fixed position. It's considered superior to vertical dryers for this reason.

Temperature management is the critical variable. Above roughly 45°C for parchment coffee, you risk case-hardening the outer bean layer - trapping residual moisture inside and creating problems that show up as flat or papery character in the cup. Well-managed guardiola drying at lower temperatures can match careful sun-drying in quality; pushed too hot, it undoes careful processing upstream.