Tumbles coffee in a heated rotating drum, or another mechanical dryer, so drying takes hours instead of days.
Mechanical drying uses heated air instead of the sun, taking hours where sun drying takes days. Guardiola-type dryers tumble coffee in a drum while hot air circulates, and were developed in Guatemala by J. Guardiola. Published guidance says drying too fast, or with the coffee mass above about 40 C for parchment and 45 C for cherry, damages quality.
How it worksIn Guardiola-type drum dryers, coffee is tumbled while hot air circulates through the drum for fast, uniform drying. Other mechanical dryer types exist, including static, vertical and horizontal rotary designs.
Step by step
- 01
Load the coffee into the dryer.
- 02
Circulate hot air while it tumbles or rests.
- 03
Keep the coffee mass below about 40 C for parchment and 45 C for cherry.
Timing · Hours, where sun drying takes days
History
Guardiola-type dryers were developed in Guatemala by J. Guardiola. A Guardiola dryer patent was being sold in Guatemala by 1880, and one source says major mill makers adopted the system after the patent expired.
Field notes
- i
Mechanical dryers generally burn wood or recycled parchment, according to one trade source.
Our notes on Mechanical Drying are still being checked against their sources, so for now this page shows only the facts we can stand behind.
What can go wrong
- Drying too fast, or with the coffee mass above about 40 C for parchment and 45 C for cherry, damages quality.
- One trade source says traditional Guardiolas usually deteriorate quality compared with newer cold-air systems.
Sources · 4 Every sentence here was checked against a source we read. Taste notes are what guides describe, not promises about your bag. Last revised 2026-09-30. Some details here are less settled than others.
- Coffee processing · Wikimedia Foundation
- Coffee Drying Methods Explained: A Guide to Traditional and Mechanical Driers · DR Wakefield
- Raw Materials: The Ins and Outs of Drying Coffee · Merit Coffee
- Josep Guardiola i Grau and his relationship with coffee · El Magnifico