Originally, coffee processing was just a way to extract the beans from the coffee berries. Producers used the processing method that allowed them to produce coffee in their climate, and no one thought much about taste.
Later, however, it became clear that the processing of the coffee greatly affects the taste of the cup. For example, under the same growing and brewing conditions, washed processed coffee will turn out more acidic than natural coffee.
This is why it is important to understand the differences between the different processing methods, and to understand how they affect the taste. This is what our article will be about.
Methods of processing coffee berries
The berry consists of six layers – skin, pulp, gluten, parchment shell (pachment), silver skin (silverskin) and grain. Each of these serves a different function: it protects from sun or damage, and it provides nutrition.
When coffee is processed, the first four layers are altered.
Depending on the number of remaining layers, there are four basic processing methods:
- Berry drying, in which the berry is dried completely. This method is also called natural or drying.
- Gluten drying, in which the berry is dried without the skin and some of the pulp is removed. One of the most confusing methods, as it has many variations and can be called khani, palp-nachural, semi-washed, or semi-dry.
- Pachment drying, in which the skin, pulp, and gluten are removed and the grain is dried in the pachment. This method is called washed.
- Grain drying in which the skin, pulp, and pachment are removed. This method is called vet hull.
- Most often, the processing method is chosen according to the weather conditions. If the climate is dry and hot, it is possible to treat coffee the natural way. This method is also used because of low costs or limited water availability, for example in Ethiopia, Yemen and Brazil.
Other processing methods are more commonly used in humid climates. They allow the grains to dry faster and avoid spoiling the crop.
Berry drying, or natural processing: Why coffee is sweeter
Drying in the berry is a classic way to process the coffee bean. It has been used since the very beginning of coffee production.
Back then, coffee was produced in Ethiopia and Yemen, where the climate was dry and there was no prolonged rainy season. Because of this, the coffee berries dried well outdoors. All coffee was treated this way until it spread to the colonies of Europeans.
In natural processing, farmers dry the coffee berries on patios – concrete pads or African beds – special tables with mesh. This usually takes up to four weeks. Some farms use special drying machines, in which they load the berries after several days in the sun.
The berry dries together with the grain, the sugars from the pulp and gluten remain in the grain. Therefore, with the same terroir, roasting and cooking, the natural processing gives the coffee a denser body and higher sweetness.
At one time, the natural processing method lost its popularity. And it was even associated with cheap coffee, because cheap beans were more often processed this way. And the lack of attention to the processing resulted in even more defects.
Now the natural processing method is widely used again. The specialty coffee industry focuses on taste, and natural processing can give a very bright taste and high cupping scores if it is done well.
Natural processing results in dried berries, which are stored for some time more in special silos to stabilize flavor and water activity. Then, before being shipped to the buyer, the dried berries are sent to hulling, where they are exfoliated and the green grains are extracted and packed in export packaging.
Drying in gluten, or hani and semi-washed processing: what the pulp is removed for
Gluten drying is divided into two main groups, the hani and the semi-washed methods. They are very similar, but there are differences.
Hani is a processing method in which the skin and part of the pulp are removed. These berries, when dried, turn a honey color and become sticky. This is why the process is called “honey”.
Immediately after harvesting, farmers depulpate the coffee, a stage in the coffee making process in which the beans are separated from the skins and partly from the pulp. The coffee is then dried to a moisture content of 10-12%.
Semi-washing or mechanical pulp separation differs from Honey processing in that after depulping coffee is sent to another machine, a demusilator. The machine removes the pulp almost completely, and then the beans are sent for drying. That is the key difference from Honey is that almost no pulp is left on the surface. Coffee dries even faster in this process.
As a result of hani and semi-washed treatments, you get dried pachment – beans covered with the last protective layer. Pachment is also stored for some time in special silos to stabilize flavor and water activity. The patchment is then sent to hulling, where it is peeled off, the green grains are extracted and packed in export packaging before being shipped to the buyer.
Pachment drying, or washed processing: why it was considered better than natural
Patchment drying differs from gluten drying in that the pulp is removed by fermentation and then washed down with water.
This method emerged when Europeans planted coffee trees in their colonies. In Indonesia, Cuba and Central America, the humid climate made it difficult to dry the berries – the crop could simply become moldy. In addition, coffee consumption was on the rise, and it was necessary to figure out how to process it faster. So in the 1850s, the British in their colony in Jamaica invented the washed method of processing.
The essence of this method:
First, the coffee berries are peeled from their skins – depulped.
Then they are fermented. For this, the berries are left in a fermentation tank with or without water. Bacteria, yeasts and other microorganisms start the fermentation process and thus destroy the pulp and gluten on the surface of the pachment.
The gluten residue is then washed off with water and the coffee is sent to dry.
Over time, washed processing began to supplant natural processing: it was the only one that could be controlled, so the coffee was of better quality. With equal growing conditions, the same roasting and preparation, this treatment produced a cleaner and more acidic flavor.
The washed treatment, as well as the hani and semi-washed treatments, results in a dried pachment, which is sent to storage to stabilize flavor and aqueous activity. The pachment is then sent to hulling, where it is exfoliated, the green grains are extracted and packaged in an export package before being shipped to the buyer.
Pachment-free drying of grains, or vet hull: what helps dry grains even faster
Grain drying, or vet hulling, removes the skin, pulp, and pachment from the berry.
First, the berries are peeled as in the washed method, fermented in water, and sent to be dried.
The main difference is that the grains are dried to 20-24%, although usually to 10-12%. Next, the still wet grains are sent for pachment removal – hulling. Once the pachment is removed, they dry faster.
The vet hulling treatment, unlike other treatments, immediately results in ready green grains, which are sent for pre-export preparation, sorted, packaged and sent to buyers.
Why it is important to know the method of grain processing
Processing methods produce different processes, which affects the taste of the coffee, so it is important not to confuse them.
However, it is worth remembering that the taste of coffee is also affected by terroir, the type of coffee, roasting, grind quality, water, and other factors.