Processing Types 

Here is a list and explanation of the common green coffee processing types. Washed, honey, natural and wet-hulled are the more traditional processing methods. With washed coffee being probably traditionally being the most popular type liked by consumers. Natural and honey type processing have gained in popularity in recent times with consumers. Which has then led to a growth in the more experimental and recently developed processes. Such as the anaerobic carbonic and lactic processes.

It should be noted also that there are other processing methods and variations of the one mentioned also. But these are the most common types or most common version of each type.

 

 

Washed Process: Coffee cherries are density sorted in water channels where floaters and debris are separated. They are then passed through a de pulper 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. Although brief this fermentation still imparts some flavour to the coffee bean. The beans are washed with fresh water to wash away the removed mucilage then dried on either patios, raised beds, or with mechanical driers. Common flavour attributes: clean and complex with higher acidity and a more pronounced brightness.

 

 

Honey Process: Is a combination of washed and natural coffee processing. The coffee is de pulped to separate the beans from the cherry. The beans not fermented in water at this point to remove the mucilage. But are laid out to dry with the mucilage still intact. They are regularly rotated to prevent mold and help them dry evenly. The terms black, red, yellow, and white honey are determined by the amount of fruit left on the bean at the de pulping stage. Black being the highest, white being the least. Once the beans are fully and thoroughly dried, a dry mill finishes the processing by removing any remaining fruit and mucilage from the coffee. Common flavour attributes: types with less fruit left are more like a washed. Where at types with more fruit left are more like a natural.

 

 

 

Natural Process:  Ripe cherry is spread out completely intact on a patio or raised beds and left to ferment and dry gradually. This can take between 3-6 weeks. The cherries are turned regularly to ensure even drying and prevent mold. The dried skins and fruit is then mechanically separated from the coffee beans at a dry-mill. Common flavour attributes: fermented or stewed fruits, winey, dark berries, heavy body.

 

 

 

Wet-Hulled Process:  A method primarily used in Indonesia, particularly in Sumatra. The coffee cherry is de pulped, like in the washed coffee process. But instead of being fermented in water to remove the thin layer of mucilage. The beans are put into bags and fermented for up to 48 hours. Then washed to remove the remaining mucilage.  They are then only partially sun-dried until they reach a moisture content of about 30%.  At this point 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%. Common flavour attributes: earthy, savoury, herbaceous, heavy in the body, darker chocolate notes and nutty.

 

 

 

Anaerobic Process: Is coffee which has a step that involves fermenting coffee beans in the absence of oxygen. The coffee is placed in a container in either cherry or depulped form with a small amount of water which is then sealed to create an oxygen-free environment. It may also be flushed with nitrogen gas to remove any remaining oxygen. This creates an environment which the remaining pulp on the beans can be broken down by bacteria and yeast which thrive in oxygen-free environments. Creating unique flavours in the coffee, from the various organic acids and other compounds that these yeast and bacteria create while working. Fermentation takes between 24 to 72 hours. Once completed, the coffee bean can then continue to be processed through traditional methods. Common attributes: heavy body, winey/rum and raisin-like flavour, tropical fruits and notes of fermented cacao.

 

 

Carbonic Maceration Process: Is traditionally a wine-making process. The coffee cherries are cleaned and density sorted then placed into containers. Which are then purged with carbon dioxide then sealed. A one-way valve is used to allow the fermentation gases to escape. The addition of carbon dioxide is key here as it causes, fermentation to begin from the action of enzymes within the cherries, rather than yeast or other microorganisms. Once completed, the coffee bean can then continue to be processed through traditional methods. Common attributes:  Depending on the time and temperature used often have an intense flavour profile, with boozy and cooked fruit notes, some are sweeter, and some more acidic.

 

 

Lactic Process: Is a type of anaerobic fermentation as oxygen has minimal interaction with the cherry. Lactobacillus is encouraged to grow by selecting very ripe coffee cherries with a high sugar content. These cherries are hand placed in sealed tanks. Conditions are closely monitored and the temperature, pH levels, and oxygen availability are controlled to create the ideal conditions for lactobacillus to thrive and become the dominant microbe in the fermentation process. Once completed, the coffee bean can then continue to be processed through traditional methods. Common attributes:  very sweet, medium to high body, strong lactic acidity notes, tropical fruit, and flavours of papaya or pineapple yogurt.

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