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Coffee Processing

Processing is the method by which the coffee cherry's fruit and skin are removed to reveal the green bean inside. The choice of processing method has as much impact on flavor as origin or variety.

Curated by Keith E. Lyons·Author of The Complete World of Coffee

Overview

After coffee cherries are harvested, they must be processed to remove the fruit and dry the seed to a stable moisture level. The three primary processing methods are washed (wet), natural (dry), and honey (semi-washed).

Washed processing removes all fruit before drying, producing clean, bright coffees with pronounced acidity. Natural processing dries the cherry intact, creating fruity, complex, and sometimes fermented flavors. Honey processing removes the skin but leaves some mucilage, balancing clarity with body and sweetness.

Experimental methods like anaerobic fermentation, carbonic maceration, and yeast inoculation are pushing the boundaries of what coffee can taste like. These methods borrow from winemaking to create entirely new flavor profiles.

Start Here

New to coffee processing? Begin with these resources.

Encyclopedia: Processing

Key terms and definitions for processing methods.

Origins and Processing

How different countries process their coffee.

Wet-Hulled Processing

Indonesia's distinctive wet hulling method and its earthy, full-bodied flavor profile.

From The Complete World of Coffee

Chapter 4: Processing Methods
Chapter 5: Fermentation Science

Learn more about The Complete World of Coffee →

Popular Guides

Most-visited pages in this topic area.

Storage

<a href="/coffee-processing/export-preparation">Storage</a> is the <a href="/coffee-processing/sorting">critical</a> phase between <a href="/coffee-processing/washed-process">processing</a> and roasting where <a href="/coffee-encyclopedia/parchment">green</a> coffee must be protected from moisture, oxygen, temperature fluctuations, and pests. Proper <a href="/coffee-processing/milling">storage</a> preserves the quality developed during <a href="/coffee-encyclopedia/ethiopia">processing</a> and drying, while poor <a href="/coffee-processing/drying-methods">storage</a> can ruin even the finest coffee. This page covers all major <a href="/coffee-processing/wet-hulled">storage</a> methods and best practices for maintaining green coffee quality.

Export

Export Preparation

<a href="/coffee-processing/milling">Export</a> <a href="/coffee-processing/drying-methods">preparation</a> is the <a href="/coffee-processing/wet-hulled">final</a> <a href="/coffee-processing/double-fermentation">stage</a> of the coffee supply chain at origin, where milled, sorted, and stored <a href="/coffee-processing/storage">green</a> coffee is prepared for international shipment. This includes <a href="/coffee-processing/anaerobic-fermentation">final</a> quality control, lot assembly, documentation, packaging, and logistics coordination. <a href="/coffee-processing/carbonic-maceration">Export</a> <a href="/coffee-processing/experimental-fermentation">preparation</a> ensures that coffee arrives at its destination in optimal condition, with all required certifications and documentation.

Drying

Drying Methods

<a href="/coffee-processing/natural-process">Drying</a> is one of the most <a href="/coffee-processing/storage">critical</a> <a href="/coffee-processing/wet-hulled">stages</a> in coffee <a href="/coffee-processing/washed-process">processing</a>, where moisture is reduced from approximately 60% in fresh cherries to 10 to 12% in stable green coffee. The <a href="/coffee-processing/pulped-natural">drying</a> method profoundly affects flavor, shelf life, and quality, making it as important as the <a href="/coffee-processing/experimental-fermentation">processing</a> method itself. This page covers all major <a href="/coffee-processing/honey-process">drying</a> techniques used in coffee production worldwide.

Milling

Milling is the post-<a href="/coffee-processing/drying-methods">drying</a> <a href="/coffee-processing/anaerobic-fermentation">stage</a> where <a href="/coffee-processing/double-fermentation">dried</a> coffee in <a href="/coffee-processing/experimental-fermentation">parchment</a> is transformed into <a href="/coffee-processing/export-preparation">export</a>-ready <a href="/coffee-processing/storage">green</a> coffee. The process involves hulling (removing the <a href="/coffee-processing/co-fermentation">parchment</a> layer), polishing, grading by size and density, and <a href="/coffee-processing/sorting">sorting</a> for defects. Milling quality directly affects the final cup quality, roast consistency, and market value of the coffee.

Sorting

<a href="/coffee-processing/double-fermentation">Sorting</a> is the quality control process where defective coffee beans are identified and removed from the lot, ensuring that only high-quality beans reach the consumer. <a href="/coffee-processing/co-fermentation">Sorting</a> occurs at multiple <a href="/coffee-processing/drying-methods">stages</a> of the coffee supply chain, from cherry <a href="/coffee-processing/thermal-shock">sorting</a> at the farm to optical sorting at the mill to hand sorting before <a href="/coffee-processing/export-preparation">export</a>.

Experimental

Double Fermentation

Double <a href="/coffee-processing/experimental-fermentation">fermentation</a> is a <a href="/coffee-processing/thermal-shock">processing</a> <a href="/coffee-processing/carbonic-maceration">technique</a> where coffee undergoes two distinct <a href="/coffee-processing/anaerobic-fermentation">fermentation</a> <a href="/coffee-processing/drying-methods">stages</a>, each with <a href="/coffee-processing/co-fermentation">different</a> conditions, to create layered, <a href="/coffee-processing/honey-process">complex</a> flavor profiles. The two stages may use different microorganisms, temperatures, durations, or environments, building depth of flavor that a single <a href="/coffee-processing/yeast-fermentation">fermentation</a> cannot achieve.

Beginner Guides

Start here if you're new to coffee processing.

Processing Methods

Coffee Fermentation

Coffee fermentation is the microbial breakdown of the sugars and pectins in the fruit mucilage surrounding the coffee seed during post-harvest processing. Yeasts, lactic-acid bacteria, and acetic-acid bacteria metabolize those sugars into alcohols and organic acids, loosening the sticky mucilage layer so the seed can be cleaned and dried. Every traditional processing method involves fermentation; what differs is how much fruit surrounds the seed and how tightly the process is controlled.

Advanced Guides

Technical deep-dives for experienced readers.

Storage

Export

Thermal Shock

<a href="/coffee-processing/experimental-fermentation">Thermal shock</a> is a coffee <a href="/coffee-processing/anaerobic-fermentation">processing technique</a> that uses rapid <a href="/coffee-processing/yeast-fermentation">temperature</a> changes to <a href="/coffee-processing/co-fermentation">alter</a> the <a href="/coffee-processing/double-fermentation">fermentation</a> <a href="/coffee-processing/honey-process">process</a> and develop unique flavor profiles. By exposing coffee to hot water or steam and then cold water, or vice versa, the producer manipulates the microbial ecology and chemical reactions during <a href="/coffee-processing/carbonic-maceration">fermentation</a>.

Experimental

Co-Fermentation

Co-<a href="/coffee-processing/experimental-fermentation">fermentation</a> is an <a href="/coffee-processing/anaerobic-fermentation">experimental</a> <a href="/coffee-processing/double-fermentation">processing</a> <a href="/coffee-processing/thermal-shock">technique</a> where coffee is <a href="/coffee-processing/yeast-fermentation">fermented</a> together with other fruits, spices, or <a href="/coffee-processing/honey-process">flavor</a>-bearing materials. The co-<a href="/coffee-processing/carbonic-maceration">fermented</a> materials influence the microbial ecology and contribute their own aromatic compounds, resulting in coffee with distinctive, often fruit-forward flavor profiles that some celebrate as innovation and others criticize as flavoring.

Experimental

Carbonic Maceration

<a href="/coffee-processing/anaerobic-fermentation">Carbonic maceration</a> is an <a href="/coffee-processing/experimental-fermentation">experimental</a> coffee <a href="/coffee-processing/double-fermentation">processing</a> <a href="/coffee-processing/yeast-fermentation">technique</a> inspired by winemaking, where whole coffee <a href="/coffee-processing/honey-process">cherries</a> are <a href="/coffee-processing/co-fermentation">fermented</a> in a carbon dioxide-rich environment before being processed. Pioneered in Colombia and Costa Rica, it produces intensely fruity, complex, and winey flavor profiles that have won major barista competitions worldwide.