Coffee processing

In coffee processing, the coffee bean is being prepared for transport, storage and roasting. Once coffee berries have been cultivated and picked, they are processed. In the various processing techniques, the coffee bean’s pulp is removed from the bean. The coffee beans are high in sugar, and processing must therefore begin no later than the second day after the beans are picked to prevent the berries from fermenting. The different processing methods have a significant influence on the flavor of the coffee.

Indian coffee beans being fermented.

Coffee processing methods

The possible methods of processing the berries are wet processed (washed), dry processed (natural) or their intermediate, semi-dry (semi-washed, pulped natural, honey, wet-hulled). These techniques also have multiple variations and names around the world. Processing coffee requires great skills and quality equipment. The differences of various processing methods are introduced below. Even later we talk about the washing stations and drying and sorting coffee.

Washed aka wet process, removes the pulp by a machine (pulping). This enables the bean to keep a small membrane made up of natural sugars around it. This membrane is removed by fermenting the beans in a large water basins. Finally, the coffee is rinsed thoroughly and dried. The bean variety will affect the character of the coffee, but in general, the washing process gives coffees a bright, acidic character and a light mouthfeel.

Natural aka dry process, leaves the coffee berry to dry as it is. The bean is allowed to soak up sugars from the pulp surrounding it. Drying is cheaper than washing, because it doesn’t require large amounts of water. The process requires great care so that the berries don’t ferment. Flavor-wise naturally dried coffees taste very juicy and even jam-like. Their mouthfeel is often heavy.

Pulped natural or semi-washed processing involves partial washing of the bean, which is why it is also called semi-washed processing. The bean is dried like a washed bean, but with a thin layer of berry pulp left on the surface. This layer is only removed after drying, in the same way as for sun-dried coffee. This allows the beans to absorb some of the sweetness from the pulp on the surface during the drying process. In terms of flavour, semi-processed coffees are somewhere between washed and sun-dried coffees: the taste is quite full-bodied with a slightly brighter flavour than natural-processed coffees. Pulped natural, honey and wet-hulled processing are different types of semi-washed processing.

Washing stations

Drying coffee in Costa Rica.

Coffee processing can be done at the coffee farm, if it is big enough to be able to afford personal equipment for it. However, with specialty coffees it is more likely, that the farmers deliver the crop to a separate washing station. Washing stations are often cooperatives formed by local farmers. It is more effective for them to take care of the processing at a shared station than to all do it personally.

Coffees from different farms are usually not mixed together even if they are processed at the same washing station. Each batch is marked as its own micro lot. Often even a single coffee farm can be formed from multiple specific lots.

Many coffees are named after the washing station. This happens often especially if the coffee isn’t named after a specific farm. Often on top of the washing station and farm, the coffee’s name might also include the name of the farmer or area. Sometimes the coffee variety is also mentioned.

Drying and sorting

After coffee processing, coffee beans are dried. The drying of specialty coffees often happens outside on drying-beds. The drying beds are designed in a way, that the beans are spread on a net and air can travel also below the beans. This enables that the coffee dries as evenly as possible. Drying the beans can take approximately 10-20 days. In the case of rain, the beans are covered by shelter.

Coffee quality testing in a farm in Guatemala.

After drying the beans are sorted by size and quality. The bad beans are removed. In many countries, the beans are graded based on their size. For example, in Kenya, AA means that the beans are extremely big. The biggest beans of the crop are usually more expensive, because they have collected the most flavors.

Finally, the coffee is packed into brown burlap sacks and sent to the world. The best coffees from the coffee producing countries are almost exclusively sold abroad, while locals usually settle for the mediocre coffees. The producing of brown burlap sacks is a big employer in many of the countries that produce coffee. That is why the bags that end up at the roasteries are rarely sent back into their origin countries.

The pictures in the article: CC Abdulla Al Muhairi, CC rohsstreetcafe.