Processing coffee so separating the coffee cherry’s fruit flesh and skin from the coffee beans is one of the most crucial aspects of farming coffee. How to coffee is processed can have a dramatic effect on the resulting cup and nowadays roasters and baristas are concentrating on coffee processing to describe the coffee. Also, lately it has become more and more popular that the farmers have started to experiment with new coffee processing methods such as anaerobic fermentation. Let’s go through the most common coffee processing methods.
The goal of processing coffee for farmers is to separate the bean from the coffee cherry but also preserve the coffee’s profitability. Even if the coffee was picked perfectly ripe and the harvest has gone really well, bad coffee processing can lead to defects which decrease the value of the coffee. Some processing methods require more time, investment and natural resources that others so choosing the right processing method can be crucial decision for a coffee farmer or producer.
Also known as the dry process, natural processing is most old school way to process coffee. After picking the coffee cherries from the coffee trees, they are spread out in thin layers to dry in the sun. The drying stations can be a little different depending on the farm or region; some use brick patios, others special raised beds (=tables) which enable air to flow around the cherries, thus more even drying. To avoid mould, fermentation or rotting, the cherries are turned regularly. Once the cherries are properly dry, the skin and dried fruit flesh are removed mechanically and the green coffee is stored and “rested” before exporting it.
The natural process is common in regions where there is no access to water such as Ethiopia and some regions in Brazil. The process is commonly traditional in the regions where it is used and no big development is seen in the natural processing during past years.
Natural processed coffees definitely divide baristas' opinions in terms of flavor; some love them, others hate them. The natural process definitely adds flavors to the coffee such as fruitiness and sweetness regardless of variety and region. Common flavor notes for natural processed coffee are blueberry, strawberry, tropical fruits and honey but on the flip side, there can be also wild, fermented flavors and alcohol-like notes. Natural coffees are often described to have red wine like flavors when compared to washed coffees. The natural processed coffees can be really useful for roasteries and baristas to showcase what coffee can taste like and open consumers minds but on the other hand they can also be really off-putting for people who don't like fermented and wild flavors in the cup.
Also know as wet processing method, is the other main way to process coffee. In the washed process all of the fruit flesh is removed mechanically from the coffee bean before the beans are dried. Removing of the fruit flesh is done with a machine called depulper. After depulping the beans are put to a water tank where fermentation process will remove the remainder of the fruit flesh. The amount of time that the fermentation requires depends on the climate and altitude. In hotter regions the fermentation will take less time and vice versa. Usually the fermentation requires 24-72 hours and if the coffee beans are fermented for too long, it will have negative effect on the flavor of the coffee. After the fermentation is ready, the coffee beans are washed to remove any leftover flesh and then it is ready to be dried. Drying in the washed process is done similarly as in natural process so in brick patios or raised beds. To ensure even drying the beans are turned regularly as in natural processing. The beans can be also mechanically dried, especially in regions where there isn't enough sunshine or excess humidity.
The washed process leads to bright and acidic flavors in the cup. It's commonly highly appreciated among roasters and baristas due to increased complexity and cleaner cup profiles. Many describe washed coffees to have white wine like flavors when compared to natural coffees. Many farmers or producers choose the washed process because properly done it reduces the risk of defects and it's more stable way to process coffee. On the other hand, it requires more water than other processing methods so it's more expensive for the farmers or producers.
The honey process is used commonly mainly in Central American countries such as Costa Rica and El Salvador. The cherries are mechanically depulped but the depulping machines are set to leave a specific amount of flesh on the beans. After depulping the beans go straight to the drying tables or patios to dry. As there is less flesh surrounding the beans, the risk of over-fermentation is lower than in natural process but the overall sweetness and body in the cup are increased by the sugars in the remaining flesh. When well done, honey processed coffee have positive attributes from washed and natural coffees; sweetness of naturals and brightness of washed.
Honey processed coffee are quite often referred with colors; black, red, yellow and white honey. The color referrers to the amount of fruit flesh that is left on the bean after depulping. Black honeys, that are also black in color have the most flesh left on the bean and white honeys the are left only a bit of flesh. This of course has an effect on the flavor of the coffee; black honeys are like naturals and white honeys like washed coffees.
Similar to honey processing is pulped natural process which uses a bit more water and strips the beans fully during depulping. Pulped natural process is mainly used in Brazil.
Anaerobic ( = oxygen-free) fermentation is one of the newest methods to process coffee and has gotten popularity especially among really high end coffee such as competition coffees. Anaerobic process is similar to washed process but the fermentation is done in fully sealed and oxygen deprived tanks. The methods is still quite experimental but anaerobic processed coffees have often wild, unexpected and complex flavors.
This method is similar to the anaerobic and it has been stolen from the winemaking world. The biggest difference to anaerobic process is that the cherries are fermented as whole and the process breaks down the cell walls of the fruit flesh from inside out. All the crazy flavors from the fruit flesh is soaked into the beans during the fermentation and carbonic maceration yields extremely crazy and incredible flavors such as red whine, whisky, banana and bubblegum to the cup.
Sounds something not related to coffee but in fact it means "wet hulled" in Indonesian language. As you might then expect, it is only common in Indonesia. Giling basah is similar process to washed process but the beans are dried to only 30-35% moisture content (11-12 % in washed process). After initial drying the parchment is removed from the beans and the "naked" beans are then dried again until they are dry enough to be stored. Giling basah yields earthy flavors such as wood, mustiness, spice and tobacco which is why it isn't highly appreciated among coffee professionals.
After the coffee has beans processed, they are still enclosed by the parchment layer (unless they are giling basah processed). Now the beans' moisture content is low enough to be stored so that they don't rotten. Usually the beans are stored in reposo ( = dry warehouse) for 1-2 months before exporting. Just before exporting the beans are hulled to remove the parchment. The hulling is done mechanically in a dry mill (opposed to a wet mill / depulper in washed process). After hulling the beans are graded and sorted with machines that examine the size and color of the beans. The beans are be also sorted by large sieves with varying hole sizes or by hand. Once the beans have been sorted and graded, they packed into 60kg or 69kg jute bags, depending on the country of origin. The jute bags are packed into a shipping container which protects the beans during their long journey to a roastery.