Having recently explored how coffee is harvested, we now wanted to take a closer look at the next phase. The processing of coffee offers up a lot of complexities, revealing how the coffee bean goes through rigorous processes to make it into the useable product we all recognise today. How is coffee processed? Alternative processes yield different flavour profiles. Therefore, the type of processing method is purposeful and has intent, in order to fabricate a result for the consumer. Typically, these methods can be separated into two camps: ‘washed’ and ‘unwashed’. The following methods reveal how coffee can be processed in a variety of ways to achieve different results.

What is naturally processed coffee? Probably the oldest and most traditional process, this method sees the coffee cherry being dried with all layers intact (unwashed). Natural fermentation occurs within the beans own environment but its the enzymatic bi-products which can influence the distinct flavour profiles of your coffee. Given the climate of most coffee producing regions, water can often be hard to come by. Therefore ‘washing’ the cherries is not feasible. Instead, the cherries are left to dry out underneath the beating sun. The secret here is to constantly turn or rake the cherries, to prevent any of the fruit from spoiling or becoming contaminated. Naturally processed coffee is now back in demand, since the coffee market has begun demanding more unique flavour profiles. Prior to this, washed coffees had been popular for their more balanced flavours.

What are washed coffees? Washed coffee is a process where water and friction are applied, in a ‘depulping machine’, to remove the pulp from the coffee cherry, leaving only the parchment and some mucilage. From here, further water is introduced, and the beans are placed into water-filled fermentation tanks. The fermentation stage is crucial, in terms of developing flavour profiles in the coffee. Regions and farmers will differ their styles and techniques, experimenting to produce the most flavourful and aromatic coffees. It’s not unusual for the fermentation stage to last between 24 to 36 hours. The longer the fermentation, the more time the beans have to absorb sugars and produce livelier, yet balanced and clean flavours. However, ferment for too long and the coffee beans will be ruined. Over-fermentation leads to high acidity and vinegary characteristics.

What is honey processed coffee? As indicated by the name of this process, this is the experimental search for the sweeter, fruitier and more complex flavours found in coffee. (Please note, no honey is used during this process). Although each farmer has their own preferences of how they conduct the ‘honey process’, the methodology is largely the same. Instead of removing and washing all of the fruit from the coffee cherry and leaving just the seedling, in the honey process, the skin is removed but the sticky, sugary layer beneath is left on to dry. It’s sticky texture and the golden colour of the mucilage is reminiscent of honey, hence its name. During the fermentation of pectin and sugars from the mucilage, some of the most complex flavours and aromas are spawned. Depending on how long the fermentation stage lasts and the method, and duration of drying, honey processed coffees can be categorised from white to black, resulting in a range of sweet and acidic flavours.

What are semi-washed coffees? Similar to the washed coffee process, semi-washing coffee requires the same depulping process, but the beans are then sun dried until the moisture content of the bean declines to around 30%. From here, the beans are ground until the parchment is removed, revealing a swollen, pale, green bean. This bean is then dried further until the moisture level is so low it is no longer at risk of developing mould. What’s left is a is a dark green coffee bean, making it instantly recognisable. A lot of Indonesian coffee is produced this way, known as ‘Giling Basah’ (wet grinding) but it doesn’t come without its problems. Removing the parchment at an early stage and leaving them out to dry under the baking sun, exposes the beans to the elements. Depending on where the beans are left to dry, the earth around them, Insects and debris can all contribute to the final flavour profile of the coffee bean. Some buyers enjoy these characteristics, whereas others see them as a defect.