The method used for processing coffee plays a huge role in the resulting coffee flavour. There are three common coffee processing methods applied by coffee producers, which we’ll discuss below.
The dry method (aka unwashed or natural) is the oldest coffee processing technique, which has been employed by people thousands of years ago.
In the dry process, the coffee cherries are left intact and are allowed to dry, just like a grape turning into a raisin or plum turning into a prune. This process allows the natural fruit sugars and alcohols in the flesh to cause fermentation. They are exposed to the sun on matting supported with trestles or on concrete or brick patios.
As they dry up, the cherries are manually turned or raked to ensure even drying and to prevent the growth of mildew. The drying process can take as much as four weeks until the cherries reach the desired moisture content, which is about 10% to 12%. Dried cherries are kept in special silos or storage before they are hulled, sorted, graded and bagged at the mill.
The dry method is extensively used for producing Arabica coffee in Brazil, Ethiopia, Haiti, Indonesia, Paraguay and Yemen. Nearly all robusta coffee beans also undergo this process. It is commonly practised in regions that have long, hot summers ideal for drying. Coffee produced through this method is full bodied, complex, sweet and smooth.
Washed or wet process
In the washed (or fully washed) or wet method, coffee cherries are sorted by immersing them in water. Good-quality cherries sink whilst bad or unripe ones float. The good cherries are collected and undergo a mechanical friction process where the skin and some of the pulp are removed as a machine presses the fruit through a screen in water.
The cherries then undergo fermentation to soften and loosen the fruit mucilage. After fermentation, the cherries are washed in a tank several times with fresh, clean water to remove the mucilage. Once the pulp and skin are removed, the only layers left on the beans are the silvery skin and parchment. The coffee beans are finally dried in the sun (or mechanically) until they reach the optimum moisture level. After drying, the parchment layer becomes dry and crumbly, making it easier to remove it during hulling.
The wet process is used in Brazil, Ethiopia, Indonesia and Yemen. Coffees made using the wet method embody the classic flavour profile expected of coffee – clean, fruity and bright.
Semi-washed or semi-dry process
Also called ‘honey processing’ or ‘pulped natural’, this technique starts the same way as the washed method until the cherries are de-pulped, leaving only some mucilage behind. But instead of getting rid of the mucilage, it is allowed to dry on the coffee beans.
The mucilage-coated beans are stored for up to a day. The mucilage is then washed off, and the coffee beans with the parchment layer still on are partially dried under the sun until they reach the ideal moisture level. Then the beans are dry-milled before being sent off to their destinations.
The pulped natural process is popular in Brazil, Costa Rica and El Salvador. It results in sweeter, fruitier flavours in the cup.
Now you have an idea of how coffee is made. The next time you sip on a cup of coffee, why not make an adventure of it? Take a guess at the origin or method used based on the coffee flavour, then check with the barista if you guessed correctly.