Coffee processing 101: a guide to help you decipher the meaning of the descriptions you find on the label of your favourite coffee! Along with the region the beans are from, how they’ve been roasted, and how to best prepare them, coffee processing methods are some of the most crucial elements that create the flavour you eventually taste in your cup.
In order to understand coffee processing, you’ll need to know some basic coffee bean anatomy. A coffee cherry has several layers:
- The tougher outer skin (pulp) or exocarp, which surrounds the fruit.
- The mucilage or mesocarp, a sticky, squishy layer that contains the sugars the coffee bean can absorb
- The parchment, a papery layer or endocarp
- The silverskin, a thin, transparent membrane covering the two seeds.
Coffee processing includes the different ways in which the coffee bean is removed from these layers within the fruit, in order to get the desired taste. This coffee processing 101 guide will help you understand these methods better, and hopefully help you try out some new beans with different processing methods!
Washed coffee is one of the most popular processing methods of speciality coffee beans. This is due to several reasons, but the main one being that it allows for very consistent flavours per batch. Washed coffee is the only method that focuses solely on the bean itself, and depends fully on the bean having absorbed enough of the natural sugars found in the mucilage during its growing phase.
Different regions of the world have slightly different ways of processing washed coffee beans, but the general process includes the following steps. Once the coffee fruit is ready to be harvested, the freshly picked coffee cherry is sent through a pulping machine, which removes the outer skin and the mucilage layer. The beans are then soaked in water, and periodically agitated to allow the pulp to slowly come off. Usually, the bean is allowed to ferment at this stage to separate any pectin that is still stuck to the bean. Fermentation is controlled and can take between 18-24 hours. This is then followed by the rinsing and drying of the beans – hence the name: Washed Coffee.
The Star of Single-Origin
Washed coffee processing perfectly reflects the science behind what it takes to grow a bean that encapsulates the desired flavours. It also shows that coffee farmers are a crucial part of crafting these flavours, proving that the environment and origin play an integral role. This is especially important for single-origin beans – these beans benefit tremendously from the washed processing method as the focus on the bean itself allows their true character to shine through even more.
Washed coffee allows you to taste the bean itself; its origin, its variety – not the effects of the processing method. Of course, that means that this method is best suited for beans that have a wonderful, stand-alone taste profile. When done right, washed coffees have a clean, lively taste. Sometimes even a fruity acidity comes along, which adds just a little bit of excitement to every sip.
Next in our coffee processing 101 guide is the natural, or as it’s also called the “dry-processed”, coffee processing method. This back-to-basics approach hails from Ethiopia. Over the years, it gained a bit of a bad reputation – as the result of inconsistencies in flavours per batch of beans. This makes it a rarer find in specialty coffee beans. But – if done right, and with new and upcoming technology becoming more widely available, natural coffees have the potential to be consistent. Additionally, they have a wonderful flavour profile, with amazing sweetness and high body stealing the show.
With natural, or dry, processed coffee, the fruit is left on the bean after it’s been harvested, and it’s left undisturbed as it dries. This means there this process requires less investment, but also requires near-perfect climactic conditions to ensure the drying process happens in time and the beans don’t get moldy. Coffee farmers used to be completely subject to the elements when it came to naturally drying the beans, but the perfect drying conditions can now be simulated. In Brazil, where a lot of the innovation in this area is taking place, the use of African bed and greenhouse patios, as well as selective pickers separating the fruits in maturation stages, allows for more consistency and less dependency on the climate in the drying stage. The moisture content of the fruit should drop to 11-12% during the drying stage, which takes 3-6 weeks. After the cherries have been dried, the seeds are separated from the rest of the fruit, which is referred to as “hulling” and happens in mills.
Taste of Fruit
Natural processed coffee has a wider range of fruity flavour notes in comparison to washed coffee, as well as having a fuller body and less acidity. They tend to score much lower on the cleanliness of the cup and can be on the sweeter side – often with flavour notes like fresh citrus or lime or a strong strawberry jam. However, the imperfections and easy exposure to damage during this processing method can lead to a chalkier, lingering taste on the tongue – which can be unpleasant. That’s the main reason why speciality coffees are usually not processed naturally, although when they are and it is done right, it makes for a beautiful brew.
Honey/Pulped Natural Coffee
Contrary to what the name suggests, there is no honey involved in this processing method. The name refers to how sticky the beans get during processing, and when right, honey-processed coffee can literally taste like biting into a sweet fruit or as if poured brown sugar in your cup. This process meets washed and natural coffees in the middle, taking the best of both worlds. It often tastes fruity, but not in the exaggerated way in which naturals taste fruity. It has a clean acidity like washed coffees but in a more rounded way. This creates a much more complex mouthfeel combined with an intense sweetness.
This processing method is strongly associated with Costa Rica and has everything to do with the mucilage surrounding the bean. Once only the ripest cherries have been picked, they are pulped from their outer skin but the sucrose-containing mucilage is left on the bean. The mucilage is highly monitored in this process, as it influences the sweetness and depth of the body of the coffee. The beans are then dried, which is the most intricate and sensitive part of the process. The timing must be perfect, as beans that dry for too quickly don’t carry the sweet flavours of the mucilage, and beans that dry too slowly most likely ferment. To achieve this perfect timing, the beans need to be raked on their drying beds every hour until the desired percentage of moisture is reached.
Honey processed coffee is a highly monitored, scientific processing method. This wouldn’t be a complete coffee processing 101 guide if we didn’t go through them! There are even subcategories that describe the slightest differences in honey processing:
- White and yellow honey’s: the beans are first washed/semi-washed and have less mucilage left surrounding the bean
- Red honey: the beans are processed under more shade, which slows the drying time and increases the beans exposure to humidity
- Gold honey: the beans are dried during warmer, sunnier times and dry quickly with minimal exposure to moisture
- Black honey: these beans take very long to dry in a deeper shade. They require constant monitoring to avoid mould developing or over-fermentation, and they should be roasted as soon as they arrive at the roaster.
Generally, lighter honey’s are perfect for filter coffees, and darker honey’s make for a beautiful, full-bodied espresso.
Alternative Processing Methods
The processing methods above are the most common that you’ll see in speciality coffees. However, there are a few wild cards out there that make for beautiful – or interesting – brews. They often come from local farmers experimenting with the different tools available to them the climate in which their farm exists. For example, in Indonesia, wet-hulled coffees are extremely popular. It involves partly drying the coffee either in full cherry or only in the parchment until it is sent to a mill where it is stripped entirely and allowed to continue drying as a raw seed. Locally this process is known as “giling basah”, and the SCA refers to it as “seed-dried” coffee processing. They tend to be the single-malt whiskeys of the coffee world, often tasting quite peaty and earthy, combined with chocolate aromatic notes.
Deciphering the Label
Hopefully, this coffee processing 101 guide can help you understand the terms used on coffee labels, as well as get a feel for the impact processing methods have on the taste that ultimately ends up in your daily cup!