What are the different coffee processing methods?
Washed
Also known as wet processing, this method uses a lot of water. It is commonly used in parts of Eastern Africa & Latin America. Once the beans are harvested they are immersed in water. The ripe cherries will sink to the bottom, while the unripe ones will float & thus removed. The ripe cherries are then forced through a mesh screen using large amounts of water pressure. This process removes most of the skin and fruit, leaving a small amount of pulp (mucilage), attached to the beans. The beans are left in fermentation tanks for about 24 hours. The fermentation process breaks down most of the remaining pulp. The beans are then washed and left out to dry until the final layer of skin around the beans can be removed. Wet processing results in better overall uniformity across the beans and the resulting coffee is known for its bright and clean taste.
Natural
Otherwise known as dry processing, this is the oldest coffee processing method. As the name suggests, this process does not use large quantities of water, and is mainly used in Brazil, Ethiopia, Haiti, Ecuador, and Paraguay. Once the coffee cherries are harvested, they are sorted for quality, then cleaned, and left out in the sun to dry for about 4 weeks. During this time the cherries are raked regularly to prevent mold from forming and to ensure a consistent drying process. Dry processing results in less uniformity than the washed method. However, it is cheaper than washed & thus, more viable in poorer coffee producing regions, as well as in regions with limited access to water.
It can result in some unique and interesting cup profiles. As the fruit dries on the beans, it is infused with flavours. As a result, dry processed coffee beans tend to be fruitier than those processed using the wet process.
Honey
Believe it or not, the honey process does not involve the use of honey! This process is essentially a combination of the dry and wet processes. There is no definitive version of Honey processing but for the most part, involves removing a large amount of the fruit using the wet process, and instead of fermenting the cherries, they are instead left to dry with some of the pulp still attached.
Anaerobic
Anaerobic processing is a newer method that’s becoming increasingly popular among specialty roasters. This process, originating from the fermentation practices in wine production, involves creating an oxygen-free environment during fermentation. The absence of oxygen alters the flavour profile of the beans & results in an unprecedented range of tastes and aromas.
By using airtight containers (fermentation tanks), coffee producers can manipulate and control the fermentation process. Varying factors such as temperature, time, and pressure play a crucial role in enhancing the flavours obtained. The result is a unique and unexpected flavour profile.
Monsooned
Monsoon Malabar is a processing method unique to the Malabar Coast of Karnataka. The process dates back to British colonial rule, when coffee was transported by sea from India to Europe. After harvesting, the beans were exposed to monsoon rain and winds along the Malabar coast for three to four months (this process is now mimicked). The beans swell, lose their original acidity, and turn a pale golden colour, in contrast to the typical colour of green coffee. The result of this process is a coffee that is often described as heavy bodied, pungent, and dry, with a chocolatey aroma and with flavours of dried spices and nuts with low acidity.