Getting coffee from the tree to your cup isn’t a simple journey. It’s grown, picked, processed, bagged, shipped, roasted, ground and brewed. Only after all that has happened, can it be enjoyed in a hot drink.
In this blog we take an in depth look at one of the most important and influential parts of that journey – processing at origin - which alongside the coffee’s varietal and growing conditions, can have a big impact on the flavour in your cup.
Types of Coffee Processing
Processing happens once the coffee cherry has been picked. It involves the removal of the coffee bean (seed) from the coffee cherry (fruit) and the drying of the beans so they can be stored and sold.
Depending on the size and sophistication of the producer, and the way of doing things in the local supply chain, this processing can happen at the farm, or at a centralised washing station (or wet mill) that processes coffee for lots of different producers in a particular region.
Today, some of the world’s most forward thinking growers are experimenting with new and different processing methods aimed at achieving specific flavours and characteristics, but the large majority will use one or more of the three most common methods described here (or slight variations on these themes):
- The Washed (or wet) process
- The Natural (or dry) process
- The Honey process
Washed Coffee Processing
What is Washed coffee?
With washed coffee, all of the cherry (the skin, fruit, and mucilage – a sweet, sticky skin around the bean) is removed before drying – through a process of de-pulping (with a machine that forces the bean out of the cherry), fermentation (which develops flavour and breaks down the mucilage) and washing (which fully removes the mucilage).
A traditional pulping machine used to strip flesh and mucilage from washed coffee
It’s generally more expensive to process coffee this way, and it requires good access to clean water, so why would a producer go to all this trouble?
Although washed coffee produces a specific flavour profile (which we’ll cover further on in this post), one of the main motivations for the producer to use this processing method is consistency – because the fruit is not attached to the seed during drying, there’s much less that can go wrong in the drying phase.
Washed coffee: step by step
When the coffee has been picked and sorted, the skin, flesh and some of the mucilage (a sticky membrane layer) is removed from the bean using a machine called a de-pulper. What remains after this is the green bean, and a thin remaining layer of the mucilage.
To remove the rest of the mucilage from the bean, the beans are then placed in tanks to ferment, which breaks down the flesh enough for it to be washed away. Generally, this process takes between one and three days, but the amount of time the fermentation takes to break down the remaining mucilage depends on a number of factors, including altitude and air temperature.
Fermentation time also affects flavour, but if a coffee becomes over-fermented it can cause defects and unwanted flavours.
Rwandan coffee cherries being added to a fermentation tank, as part of the washed process at Kopakama co-operative
After fermentation, the beans are removed from tanks and rinsed – often by being pushed through narrow troughs full of water – to remove the rest of the mucilage and debris. This is the ‘washing’ that gives the process its name.
Rwandan coffee being washed at Kopakama the co-operative, Rwanda
The green beans are dried – either spread out on a patio or on raised drying beds to dry in the sun, with regular turning. Mechanical drying does take place in regions where there’s less available sunshine, but slow and even drying tends to produce higher quality coffee, and coffee that ages less quickly once roasted.
Ugandan washed coffee being patio dried by one of our producer partners, Kawakom in Sipi Falls
Colombian washed coffee being dried on raised beds, at Finca Villa Maria, La Plata
Resting, Hulling and Grading
Finally, the coffee is rested (typically for between 30 and 60 days), before being hulled at a dry mill to remove the protective parchment layer, graded, and bagged for export.
Where is washed coffee produced?
While washed coffee is a widely used method in many coffee growing regions around the world, and Indonesia produces the highest volume, some of the most notable specialty washed coffees can be found in African countries like Kenya, Rwanda and Ethiopia.
Kenyan washed coffees are known for being some of the cleanest, brightest coffees you’ll come across, with fruity, berry notes and intense acidity. Rwandan coffees are renowned for fresh fruit flavours like apple, grape, and berry. Ethiopia is known for its elegant and complex washed coffees, with citrus and floral notes.
Natural Coffee Processing
What is Natural coffee?
The natural or dry process is the oldest method of coffee production, needing much less equipment than washed processing, and no water. But what it brings in terms of accessibility to the farmer is tempered with unpredictability, and the labour cost needed to carefully tend to the cherries during drying.
After harvesting, coffee is immediately laid out in the sun to dry, often for several weeks on a patio or raised drying beds, with frequent raking and turning. With this technique, coffee is dried with all the layers of the fruit fully intact, triggering a natural fermentation where sweetness from the cherry and mucilage are transferred to the bean.
Done well, the natural process can produce coffees that are sweet, fruity, wild and sometimes boozy. But on the flipside, it can be difficult for a farmer to achieve a consistently high-quality lot because of the tendency for uneven drying to produce under-ripe or overripe cherries.
The combination of its low cost and risk means that globally, natural processing tends to be reserved for low quality, poorly grown coffee confined to commodity markets that provide very little income to the farmer. In some regions, due to lack of available water, it’s the only process available to them. But for those with the skill and patience to develop high quality natural coffee, the resulting coffee can be spectacular.
Natural coffee: step by step
Immediately after harvesting, coffee cherries are sorted by hand to get rid of unripe or damaged ones, before cleaning.
Ripe cherries are then placed in the sun to dry with all the layers of the fruit intact (no pulping at all). Some producers lay them directly on concrete or brick patios, while others use raised drying beds that give the cherries better access to air flow for more even drying.
Colombian natural coffee being dried on raised beds, at Finca La Negrita
Drying coffees naturally can take up to four weeks and the cherries need to be turned regularly through raking, to avoid over-fermentation, rotting or mould growth. Generally, the more time the bean remains in the coffee cherry, the sweeter it will become, but it will also start to take on boozy, fermented flavours, which may be desirable or not, depending on the flavour profile that’s being aimed for.
Resting, hulling and grading
Once the cherry is dried out and resembles a raisin, it will be rested, before being hulled to remove the outer fruit layers and protective parchment. It’s then ready for grading and bagging for export.
Where is natural coffee produced?
Naturally processed Arabica coffees are often produced out of necessity in areas where water resources are limited, like Ethiopia, or where production costs need to be kept low, like some areas of Brazil.
Because of increasing demand for high quality naturals, though, they are now being produced out of choice in the majority of coffee growing origins – and we’ve recently sourced incredible naturals from Mexico, Colombia, El Salvador, Uganda and even Rwanda, where pre-2017, washed coffee was the only method available due to quality control laws set by the government.
Honey Coffee Processing
What is honey processed coffee?
The honey process is a hybrid of the natural and washed process, and was invented as a method to produce consistent, high quality coffee like that produced by the washed method, but with less water.
Much like washed coffee, the cherry and some of the mucilage is removed by a mechanical de-pulper, but instead of fermenting and washing the coffee to remove the rest, it goes straight to a patio or raised beds for drying.
Here, the removal of the cherry reduces the risk of defects arising during drying (though the risk is not as low as with the washed method), but without the need for water, the process is more cost effective, environmentally friendly, and accessible for those in dryer climates.
Practicalities aside though, the in-betweenness of the honey process means that producers can achieve some pretty unique cup characteristics. Honeys are often crisp and clean like a washed coffee, but with the dialled-up sweetness and body of a washed.
Where is honey processed coffee produced?
Although the process started in Brazil (where it can sometimes be called ‘pulped natural’ or ‘semi-washed’), it’s been perfected in places like Costa Rica and El Salvador where it’s monitored and adjusted to achieve specific flavour profiles.
For example, the amount of time the coffee is kept in the cherry, and the amount of mucilage that is left on the coffee while it’s drying, will affect the sweetness, acidity and flavour profile of the coffee and can be adapted accordingly.
This is why you may come across ‘yellow’, ‘red’ or even ‘black’ honey processed coffee, with each term representing a slight difference in method.
How does coffee processing affect flavour?
Compared to coffees processed using other methods, washed coffees are often described as bright, clean and vibrant, with a higher level of acidity and a lighter body. They’re often juicy and floral – with clear citrus fruit notes like orange, grapefruit and lime.
Washed Rwandan coffee being sifted before drying at Kopakama co-operative
Because natural coffee takes on a lot of the sugars from the cherry during drying, they tend to taste sweeter, more intensely fruity and sometimes boozy and fermented, with a heavier body. Where washed coffees tend to contain sharper, citrusy notes, natural coffees will taste of berry or summer fruit notes like blueberry, strawberry, mango and pineapple.
Honey Processed Coffee
Because of the variations in honey processing techniques, they can have a pretty wide range of flavour profiles. Generally though, they tend to sit in between washed and natural in terms of their level of acidity and sweetness. Fruity, but not as in your face as some naturals. Acidic, but perhaps in a more rounded way than some washed.
Which kind of coffee processing is best?
No process is better than the other. Although each of these processes can have a dramatic effect on coffee characteristics and flavour profiles, in reality only a small percentage of producers will choose to process their coffee in a certain way because of this. It’s usually down to practical factors like climate, cost, their attitude to risk and the availability of water.
More experimental farmers may process some of their coffee in one method, and the rest in a different method to highlight the difference in flavour processing can make.
For the Taylors Discovery online shop, we source our coffees based on their quality and seasonality and we’ll always try to showcase a variety of processing methods at any one time.