Coffee : Extraction
The coffee beans are extracted by two methods, Washed and Died (Natural)
It is important to note that the processing of coffee, specifically washed coffee, varies notoriously from region to region. But lets cover the basics:-
The cherries are sunk into water to continue sorting, ripe cherries will sink to the bottom while unripe cherries will float facilitating their elimination. Afterwards the cherries are pulped, which contrary to its name is the process of removing the “cascara” or red skin. To facilitate the removal of the mucilage the coffee fruit is fermented. This is where the most variety exists.
In Latin America, fermentation happens over night, in Kenya fermentation can take up to 3 days, and in Ethiopia it happens under water. These variations in technique come from climate and tradition and are monumental in the flavors of coffee. These flavor affecting techniques could benefit from controlled studies and research given there is much we don’t know about what is happening at this stage of processing. The fermentation process must be closely monitored or else taste of ferment will be present in the cup. But to continue; the fermented cherries are washed to remove their pulp, this happens by running the cherries through streams of water while raking the cherries.
The second mucilage removal method is machine facilitated, meaning the cherries are sent through machinery that polishes the beans until the entirety of the pulp is removed. Although similar, many farms have different washing equipment. Given every step of processing from seed to cup is present in the final extraction, it is interesting to see how washed methods of even same varieties and regions can vary from farm to farm. After the beans have been removed of its fruity companions they must be dried and become parchment coffee or in “pergamino”. Beans are either dried on raised beds, patios (in the past clay patios where fashionable, recently concrete patios have yielded better results), or commercial dryers.
The drying stage is very important; it is crucial to let the beans hold on to an exact amount of humidity that preps them for roasting. This processing method results in a very clean cup and is by and far the most common. The washed method tends to use about 2000 L of water per 50 lb bag of green beans.
Dry (Natural) Processing
Dry processing was the first method used to process coffee. As specialty coffee grew as an industry and roasters were finding cleaner cups with washed coffees, this method faded. Brazil being a very large producer of coffee, was still processing coffee in the dry manner. Almost as an advertising campaign, it was the Brazilians who coined the term “Natural” for dry processing. For this method cherries are harvested then sorted up to 3 or 4 times. The ripe cherries are then allowed to rest on either raised beds or patios to dry out in the sun. This process takes anywhere from 1 to 4 weeks depending on cherry humidity and climate. Throughout this process producers rake or rearrange the cherries to promote even drying. The cherries are allowed to dry until they reach a humidity level of around 11%. Then the cherries are removed of their pulp and parchment. This method is more common where potable water is scarce. It is also a great way for small cultivations to start their operation given it operates at much lower cost. This method does not result in a cup as clean as the washed method but can have heightened sweetness and more fruit notes found in the cup.