Coffee Processing Glossary

Understanding technical terms and industry jargon can be a daunting task, especially when it comes to a complex and specialised topic like coffee processing. Coffee processing is a constantly evolving part of the coffee suply chain, with new methods and adaptions of established ones, seemingly appearing every day.

That's why we have created this Coffee Processing Glossary, which includes descriptions of the processing methods we've encountered to date. We'll keep this updated as we discover new methods through our sourcing and partners so check back whenever you encounter something new.

Whether you're new to the world of coffee or an experienced roaster or barista, we hope this glossary will help you navigate the terminology and understand the nuances of different coffee processing techniques.

Processing Methods

Anaerobic Process

Anaerobic coffee fermentation is a processing method that involves fermenting coffee beans in the absence of oxygen. This is typically achieved by placing the coffee beans in a sealed container or tank.

The process starts with the depulping of the coffee cherries, after which the beans are placed in a sealed container with a small amount of water to create an oxygen-free environment. The container may also be flushed with nitrogen gas to ensure that no oxygen is present.

During the anaerobic fermentation process, the coffee beans are broken down by bacteria and yeast that thrive in oxygen-free environments. This leads to unique and complex flavors in the coffee, as the bacteria and yeast produce various organic acids and other compounds that affect the flavor profile.

The duration of the fermentation process can vary depending on the desired flavor profile, but it typically ranges from 24 to 72 hours. Once the fermentation process is complete, the coffee cherry can then be processed through traditonal methods.

Bio-Innovation Process

Created by La Palma & El Tucán, this process follows the principles of organic farming. Firstly, La Palma capture and reproduce microorganisms discovered in their farm's forests, then use these to create their own fermentation substrate, which is mixed with perfectly ripened cherry in clay pots before being sealed and left to ferment for 100 hours. This process allows the establishment of a sustainable closed cycle as after the fermentation, any organic waste is repurposed as compost.

Once the fermentation process is complete, the coffee cherry can then be processed through traditonal methods.

Burundi Washed Process

Similiar to Kenya washed coffees, coffee cherry is depulped prior to a "dry fermentation" period lasting approximately 12 hours. This is then followed by a traditonal wet fermentation where the coffee is soaked for a period of 12-14 hours in fresh water tanks. The beans are density sorted by floating through channels, before another 12-18 hour soak before being dried on raised beds.

Carbonic Maceration

Originally a wine-making process, coffee cherry is first cleaned and density sorted before being placed into sealed containers. The containers are then purged using carbon dioxide to remove oxygen and other gases. After purging, the containers are sealed with one-way valve lids that allow gas to escape during fermentation but oxygen cannot enter.

Due to the high levels of carbon dioxide in this environment, fermentation begins through the action of enzymes within the cherries, rather than yeast or other microorganisms.

Once the fermentation process is complete, the coffee cherry can then be processed through traditonal methods.

Honey Process

A combination of washed and natural coffee processing. Coffee cherry is passed through a depulping machine to separate the beans from the cherry. The beans are not fermented in tanks however and the mucilage is left on the beans ; this is what gives these coffees their unique flavor. The beans are then laid out to dry - regularly being rotated to ensure even drying and to prevent mold from forming. Different types of honey processing, generally black, red, yellow, and white are determined b y the amount of fruit left on the bean when the cherry is depulped..

Kenya Washed Process

Similiar to Burundi washed coffees, coffee cherry is depulped prior to an initial fermentation period, where little or no water is used, lasting approximately 24-36 hours. The beans are then flushed in channels to remove the loose mucilage, and any "floaters" are removed.

This is then followed by a traditonal wet fermentation where the coffee is soaked for a period of 12-24 hours in fresh water tanks. After this second fermentation, the beans are then transferred to raised beds to dry.

Lactic Process

This kind of fermentation is classified as ‘Anaerobic’ as oxygen has minimal interaction with the cherry. Fully ripe cherry with high sugar content is selected for this method as high sugar environments are ideal for the growth of lactobacillus cultures. Once the cherry arrives at the mill, it is hand sorted and placed in sealed tanks.

During the fermentation process, producers will closely monitor and regulate the temperature, pH levels, and oxygen availability to create the ideal conditions for lactobacillus to thrive and become the dominant microbe in the fermentation process.

Once the fermentation process is complete, the coffee cherry can then be processed through traditonal methods.

Natural Process

Ripe cherry is spread out completly intact on a surface like a patio or elevated beds, and left to dry gradually. The cherry is allowed to dry for between 3-6 weeks, during which time it is turned regularly to ensure even drying throughout the coffee bed. The dried skin and fruit is then mechanically separated from the coffee beans at a dry-mill.

Pulped-Natural Process

A combination of washed and natural coffee processing. Coffee cherry is passed through a depulping machine to separate the beans from the cherry. The beans are not fermented in tanks however and the mucilage is left on the beans ; this is what gives these coffees their unique flavor. The beans are then laid out to dry - regularly being rotated to ensure even drying and to prevent mold from forming.

Washed Process

Ripe cherry is selected before being density sorted in water channels where floaters and debris are seperated. Cherry is then passed through a depulper to remove the skin and fruit from the coffee bean. The beans are then fermented in tanks of water for up to 24 hours to remove the remaining mucilage.

Post fermentation, the beans are washed with fresh water before being transferred to dry on patios, raised beds, or inmechanical driers.

Wet-Hulled Process

Wet-hulled coffee processing, also known as semi-washed or semi-dry processing, is a method primarily used in Indonesia, particularly in Sumatra. Firstly the coffee cherry is depulped, similar to the washed process, but instead of fully washing and drying the beans at this stage, they are left with a thin layer of mucilage.

The beans are then stored in a bag, and allowed to ferment for up to 48 hours. After this, the beans are washed to remove the remaining mucilage and then partially sun-dried in the sun until they reach a moisture content of around 30%.

Finally, the coffee undergoes a unique process known as "hulling," where the parchment layer is removed while the beans are still partially moist. This process is done using traditional hulling machines. The beans are then dried again to a moisture content of around 12%.