After harvesting coffee cherries, another very important step occurs – their processing. There are several methods of coffee processing, and we will now introduce you to the most common ones.
Three Basic Methods of Coffee Processing
When coffee cherries are harvested, they must be processed as soon as possible so that they do not start to rot or grow mold. Some farmers are able to cover this process themselves, others, especially members of larger communities and cooperatives, send them to central processing stations.
The way in which coffee cherries and subsequently green coffee beans are processed has a dramatic effect on the final taste of the coffee in the cup, and thus on its selling price. This is one of the reasons why the processing method, together with the country of origin and the roasting method, is an important part of the description and characteristics of any higher-quality coffee.
However, to avoid confusion: green coffee processors do not determine how they are processed according to the final taste they want to achieve. Taste tones occur naturally in coffee and are determined by their terroir. The goal of all coffee processing is to have the smallest possible occurrence of the so-called defects, and thus the best possible quality and the highest possible financial value of coffee.
Did you know that…? Under the processing station, you can imagine anything from a small farm with a few tools to very large, industrial stations that can process a large amount of coffee.
The choice of a specific method is determined by several parameters – in addition to the country of origin, it also looks at the availability of water or air temperature. Although some coffee processing methods require more time, investment and natural resources than others, choosing the right one is very important for coffee producers, especially when it comes to premium specialty coffee.
The three most commonly used coffee processing methods include: the natural or Dry Method, the washed or Wet Method, and the pulped natural method, also known as the Honey Method. Let’s take a closer look at each and explain the basic differences.
Dry or Natural Coffee Processing
The dry method, often referred to as natural or dry-processed, is one of the oldest, but also the simplest and inexpensive way of processing coffee. It is most often used in parts of the world where access to water is limited, such as Ethiopia and some areas of Brazil.
Whole, unprocessed coffee cherries are immediately spread even on the ground or on concrete floors, where they are allowed to dry. In order for the sun and wind to dry all the cherries evenly, farmers must turn and rake them regularly. Otherwise, the cherries could start to grow mold, rot or ferment, which could endanger the whole crop.
Did you know that…? Using horses to rake cherries is a specialty in Haiti. Horses often deform the grains, which, however, is not considered a defect when sold, but rather a peculiarity.
While on some farms the drying of cherries is done by hand, elsewhere they use animals or, for example, small tractors. Some plantations even have mechanical dryers available, which can speed up the whole process considerably. At night, the fruits are covered to prevent moisture from entering them, which could trigger the fermentation process.
After drying, which lasts about 20 to 30 days, the peels are removed from the cherries – most often using machines, while a layer of so-called parchment. Subsequently, the grains cleaned in this way are sorted according to size and quality, which is usually done by women by hand. The grains processed in this way rest for another month or two, and then go to roasteries around the world.
What Does Dry-Processed Coffee Taste Like?
Coffee whose beans have been processed by the Natural method have a stronger and more pronounced body. This is due in particular to the various substances which are released from the peel and pulp during drying and are gradually absorbed into the green coffee beans. Coffee processed in this way generally has a more diverse taste profile, it is often possible to find syrupy sweet, honey and fruit tones, and with extra careful processing, some of the coffees may also conceal slightly spicy tones.
Although this method of processing is mainly used for low-quality, unripe coffee or beans intended for the domestic market, there are also producers who use it for high-quality selected beans. In such cases, however, the whole production process is usually a bit more expensive, as there is more work involved in drying the cherries consistently and accurately.
Wet Coffee Processing
Also referred to as washed, fully-washed or wet-processed, it is much more demanding to process than dry processing. Since this method focuses exclusively on the bean, not its packaging, it can be used to obtain truly high-quality beans, and therefore much higher-quality coffee, thanks to very gentle and precise processes. The wet method of coffee processing is widespread especially in Latin America and southern parts of Africa.
After harvesting, coffee cherries first go into special water tanks, where they are washed and sorted. Dried, unripe or damaged fruits are lighter, so they float to the surface; on the contrary, ripe cherries sink to the bottom of the container. After washing and selection, the upper peel and part of the pulp are removed using the so-called depulper, which is a machine resembling a large grinder. For wet processing coffee, it is important that the peel with pulp is removed within 24 hours of harvest, otherwise it dries to the grain and is much more difficult to remove, which can ultimately lead to grain damage.
The cleaned grains then go into so-called fermentation tanks, where a fermentation process takes place in which the enzymes release the remnants of the peels and pulps. The fermentation can take 12 to 36 hours, the length of which is affected by the amount of residual pulp and parchment, the amount of microorganisms in the tank and also the ambient temperature. If the grains fermented for too long, they could start to rot, ruining the whole batch. After fermentation, the grains contain about 50% moisture, so they still need to be dried.
Did you know that…? Prior to processing, the coffee beans have a moisture content of about 60%. After processing, their humidity should be around 11-12% so that they can be stored safely until sold.
On smaller farms, the grains are dried using the sun and wind, either directly on the ground, on concrete floors or on raised beds. Drying lasts 14 to 21 days, during which the grains are regularly rolled up and rotated to dry evenly. If there is little sunlight, it is too humid or it is a large farm with equipment, the grains can also be dried in mechanical dryers with hot air. Although the processing of coffee by the wet method is a much more demanding process, which also uses a large amount of water – 130 to 150 liters of water are consumed per 1 kg of green coffee – the coffee is very well suited to this method. The wet processing process is the best of all methods to highlight the quality of the grains, which is then reflected in the cup.
How Do Wet Processed Coffees Taste?
Wet-processed coffees taste very fresh, fruity, floral and have a higher acidity than dry-processed coffees. Their resulting taste is influenced not only by the fermentation process, but also by the fact that the substances contained in the peel and pulp are not absorbed into the grains.
The so-called washed coffees have a light to medium-complex body with a very clear acid profile, which carries tones of citrus fruit. Overall, these coffees have a higher complexity, which is often described as purity in the cup, indicating the absence of any negative flavors.
Processing of Green Coffee by the Honey Method
Also referred to as Honey, semi-washed or pulped natural, belongs to the so-called hybrid methods that combine basic processing processes. It was developed by farmers in Brazil who wanted their coffees to have a wider range of flavors. Currently, however, this method is most commonly associated with Costa Rica and El Salvador.
Did you know that…? While on large farms they determine the moisture content of grains by a special meter, farmers from small plantations have developed their own technique over the years, where they estimate the moisture level by chewing the grain with their teeth. Depending on whether they are soft or hard, they can determine if they still need to be dried.
The Honey Method is a combination of the previous two methods, in which coffee cherries are first placed in water tanks where ripe pieces are selected. Then a part of the peel and pulp is removed from them by means of grinders and subsequently the grains thus treated with the remnants of parchment and pulp are allowed to dry in the sun. As with the dry method, regular and frequent rotation of the grains is important here – in some plantations they are turned every 15 minutes. After thorough drying, the peel and pulp residues are removed from the grains.
As the remnants of the peels and pulps are left on the grains, which during fermentation become a compact, sticky layer resembling honey, the name of this processing method was derived from this world-famous sweetener. The advantage of the Honey Method of coffee processing is that it is carried out without washing with a large amount of water, which significantly reduces processing costs. In addition, farmers do not have to carry coffee anywhere and can process it themselves directly on the farm.
What taste does coffee processed by the Honey Method have?
Since the tops of coffee cherries contain a high percentage of sugars, which are gradually fermented and released into the beans, coffees processed with the Honey method obtain a delicate but distinctive body without overly acidic tones. They are characterized by a fuller body with strong sweetness.
Because the Honey method combines the best of both Wet and Dry Methods, it is also reflected in the final taste of coffee. Although some coffees may be more acidic, their acidity is milder than coffees processed by the Wet Method. This is mainly related to the mentioned sugars, and thus to the preservation of greater sweetness. For this reason, “honey” coffees have a syrupy sweet body and a very wide range of taste properties.
Alternative Coffee Processing Methods
The world of coffee is large and varied, and along with its processing methods. In this blog, we wanted to introduce you to the most famous and widespread methods. However, farmers from different parts of the world are constantly developing their own ways of processing coffee cherries, thanks to which their beans acquire a literally unmistakable taste in the cup. However, more about that next time…
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