We sure do spend a lot of time talking about processing but it impacts the cup in a big, big way so in a coffee husk, here is what it all means…processing encompasses every step that is done at origin from hand picking the cherries at harvest time to when it when it is dried milled and readied for shipment. The seed from the coffee cherry must be removed from the fruit that surrounds it. Three common methods are commonly used: washed, semi-washed and natural.
The wet method makes a really clean cup of coffee that is crisp, delicate and showcases sparkling acidity.
Separating the beans from the pulp and skin must be done on the same day the workers pick the cherry from the branches, in order to maximize the flavor potential of good quality coffee beans. The wet method (also called the washed method) requires the use of specific equipment and substantial quantities of water. When properly done, it ensures that the intrinsic qualities of the coffee beans are better preserved, producing a green coffee which is homogeneous and has few defective beans.
Washing: Wet processing, removes the red skin and fleshy pulp material through a process called pulping. First, they are immersed in a pool of water, to remove any twigs and stones.
Next, they go to the pulping machinery, which removes the red skin from the two coffee beans inside each cherry. The pulp is collected and afterwards reused as an ecological fertilizer on the plantation.
Afterwards it goes into the fermentation box, where the natural process triggers a series of chemical reactions that enhance the flavor quality of the roasted coffee.
When the fermentation is complete, the coffee is thoroughly washed with clean water in tanks or in special washing machines. The wet parchment coffee at this stage consists of approximately 57% moisture. To reduce the moisture to a maximum 12.5% the parchment coffee is dried either in the sun, in a mechanical dryer, or by a combination of the two. The sun-drying is done on extensive flat concrete or brick areas, known as patios, or on drying tables made of fine-mesh wire netting. The beans are laid out in a layer of 2 to 10 cm, and turned frequently to ensure even drying. Sun-drying should take from 8 to 10 days, depending upon ambient temperature and humidity. Coffee dries more quickly if raised on tables because of the upward draught of warm air. The use of hot-air drying machines becomes necessary to speed up the process in large plantations where, at the peak of the harvesting period, there might be much more coffee than can be effectively dried on the terraces. However, the process must be carefully controlled to achieve satisfactory and economical drying without any damage to quality.
After drying, the wet-processed coffee, or parchment coffee as it is commonly known, is stored and remains in this form until shortly before export.
The dry method makes for a wild and rustic cup! Heavy body, subdued brightness and lots of jammy fruits!
The dry method (also called the natural method) is the oldest, simplest and requires little machinery.
The method involves drying the whole cherry. There are variations on how the process may be carried out, depending on the size of the plantation, the facilities available and the final quality desired. The three basic steps, cleaning, drying and hulling, are described below.
First, the harvested cherries are usually sorted and cleaned, to separate the unripe, overripe and damaged cherries and to remove dirt, soil, twigsand leaves. This can be done by winnowing, which is commonly done by hand, using a large sieve. Any unwanted cherries or other material not winnowed away can be picked out from the top of the sieve. The ripe cherries can also be separated by flotation in washing channels close to the drying areas.
The coffee cherries are spread out in the sun, either on large concrete or brick patios or on matting raised to waist height on trestles. As the cherries dry, they are raked or turned by hand to ensure even drying. It may take up to 4 weeks before the cherries are dried to the 12.5% maximum moisture content, depending on the weather conditions. On larger plantations, machine-drying is sometimes used to speed up the process after the coffee has been pre-dried in the sun for a few days.
The drying operation is the most important stage of the process, since it affects the final quality of the green coffee. Coffee that has been overdried will become brittle and produce too many broken beans during hulling (broken beans are considered defective beans). Coffee that has not been dried sufficiently will be too moist and prone to rapid deterioration caused by the attack of fungi and bacteria.
The dried cherries are stored in bulk in special silos until they are sent to the mill where hulling, sorting, grading and bagging take place. All the outer layers of the dried cherry are removed in one step by the hulling machine.
The dry method is used for about 90 percent of the Arabica coffee produced in Brazil, most of the coffees produced in Ethiopia, Haiti and Paraguay, as well as for some Arabicas produced in India and Ecuador. It is not practical in very rainy regions, where the humidity of the atmosphere is too high or where it rains frequently during harvesting.
Pulped natural coffee can have more body and lower acidity than the washed process, and a cleaner, more uniform cup than the natural process. They are sweet and balanced.
Coffee is dried in parchment just after pulping system
Honey coffee is a process where some of the mucilage that covers the bean is left in it by less washing. The pulped natural method consists of pulping a coffee, but emitting the fermentation stage to remove the silverskin. This results in a beverage that has characteristics of both a dry- and wet-processed coffee. It is often sweeter than wet-processed coffees, has some of the body of a dry-processed coffee, but also retains some of the acidity of a wet-processed coffee. The mucilage that covers the bean is packed with sugars and that is what generates the different taste. During the drying, specially if you do it under the sun like us, the parchment will take on a slight orange color. The perfect stage of the harvest to do the honey coffee is the center of the harvest, where the coffee cherry is naturally packed with more sugars, it oozes the honey.
This type of processing can only occur in countries where the humidity is low and the coffee covered in the sweet mucilage can be dried rapidly without fermenting. Brazil has made this method famous and produces some of the best pulped natural coffees in the world. All twenty winners of the Gourmet Cup competition in Brazil in 2000 processed their coffees using the pulped natural method.
WET HULLED/SEMI WASHED:
Rustic and earthy the semi washed/wet hulled method compliments many of the unique characteristics of the prized coffees of Asia and the Pacific. Wet hulled coffees tend to be the single malt whiskies of the coffee world- often peaty and earthy with chocolate aromatic notes.
Wet hulled coffee drying in Sumatra village.
Semi-washed coffees are best described as “wet hulled”, localy called Giling Basah, and will have more body and often more of the “character” that makes Indonesians so appealing and slightly funky. In this process, the parchment (the green seed with the parchment shell still attached) is very marginally dried, then stripped of the outer layer, revealing a white-colored, swollen green bean. Then the drying is completed on the patio (or in some cases, on the dirt), and the seed quickly turns to a dark green color.
Sumatra is best known for its wet hulled processing. Processing starts on the small-holder farms, where they pick the coffee and pulp off the fruit skin in a hand-crank machine. Then most farmers ferment the coffee in small containers to break down the fruity mucilage layer, others simply leave the bags of cherry intact overnight and pulp in the morning. Then they dry the coffee for a few hours on tarps or concrete, and sell it in the local market to coffee collectors. The collectors might dry the coffee a little more, but it is still exceptionally wet when they hull it (hence the term wet-hulled. This wet-hulling is not done anywhere else in the coffee world. The collector then puts the wet, soft green bean (called Kopi Labu, or pumpkin coffee) out on the tarps or concrete to dry. That’s another unique aspect of Sumatra processing; nowhere else is the green bean exposed directly to the elements to dry. But in this wet climate, hulling off the outer parchment layer so soon makes the coffee dry much faster, and allows the collector to get it dried down to 14% moisture and sell the coffee to an exporter much sooner than other processing methods. The dried coffee, called Asalan, is prepared on gravity tables and hand sorted again by the better exporters to meet the standards of Grade 1. It takes some work to find a good Mandheling-type coffee, one that doesn’t “cross the line” from pleasant earthy tones into the realm of dirty flavors (or worse of all, musty or moldy notes).