Processing is an important part of every coffee’s journey from seed to cup. After a coffee is harvested, it undergoes a processing method in which the coffee beans are removed from the raw fruit. There is no doubt that how a coffee is processed after harvest can dramatically affect the quality of the coffee and the resulting cup profile.
In recent years experimental processing methods have been used in an attempt to create new flavour profiles. There is a growing trend for these skilled producers to use different methods of processing in an attempt to generate specific qualities from their coffee. However, these producers are limited on the global scale. The majority of coffee producers choose a processing method which will most likely guarantee consistency and reduce the risk of defects, ultimately ensuring their coffees quality and value.
The two most popular methods of processing are the natural process and the washed process.
The natural process
The natural process, also known as the dry process, is arguably the oldest and most traditional method of processing coffee. During this process, the newly harvested coffee cherries are spread out in a thin layer and sun dried. Some producers spread the coffee cherries out on brick patios, whilst others use drying tables. To ensure even drying and to prevent mould, the cherries are raked regularly throughout the day. Once the coffee is dry, which can take several weeks, the dried fruit and outer skin are removed and the coffee is stored for export.
When done properly, natural processed coffee results in a smooth and heavy bodied brew. As the fruit acts as a natural casing, fermentation happens in a closed environment which adds lots of sweetness and fruit flavours to the bean. Natural processed coffee has the most incredible cup profile with flavours such as blueberry, strawberry or tropical fruit. However, it should be noted the natural processing of coffee is unpredictable. Coffee processed this way throws up more defects and the quality is often inconsistent. Coffee bean buyers are therefore committed to picking the best lots out of each cupping flight.
The washed process
The washed process, also known as the wet process, produces the highest quality of coffee.
The goal of the washed process is to remove all of the sticky flesh from the coffee seed before it is dried.
After the ripe coffee cherries are picked, the outer layer is removed using a machine called a depulper. This exposes the beans in their sticky pulp which is called mucilage. It is this mucilage, which consists of sugars and alcohol, that contributes to the sweetness, acidity and overall profile of the coffee. The beans with their mucilage are then fermented in water tanks for between 1 and 2 days, depending on the altitude and temperature. The hotter it is, the faster this process is. The duration of fermentation can result in different flavour profiles of coffee, however over fermentation can lead to negative flavours and characteristics.
Following fermentation, the beans which are now free from their mucilage are washed to remove leftover debris and ready to be dried. In the same way as the natural process, the coffee is spread out in the sun on brick patios or drying tables and turned regularly to ensure slow and even drying. It is widely accepted that a slower drying time contributes to greater consistency and complexity in the cup. Compared to other processes, washed coffees tend to produce a ‘cleaner cup’ which is free from negative characteristics such as harshness.
Our personal preference here at Cubist Coffee is washed processed coffee. This is due to the clean, well balanced nature of the resulting cups. We feel that coffees processed correctly using the washed process provide brighter and more acidic notes like no other.