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The processing of coffee beans

Coffee beans are actually the seeds of coffee cherries, thus processing is needed to separate the fruit from the seeds. Depending on the method employed, coffee beans receive different flavours during processing. For this reason, in marketing this method is shown in the name of the coffee or among its characteristics.

The journey of every coffee begins with harvesting that can be carried out at once, or according to ripeness. The harvested fruit is sorted: the unripe, overripe, and defective cherries are sorted out. Subsequently, the pulp and other parts are removed from the fruit using various processes until only the seeds covered with a silver film remain. The methods of processing do not depend on the coffee varietals, but regional differences can be observed. There are fundamentally two main groups of processing - a dry and a wet method - which can be further divided into types based on the technology used.

 

 

 

The most widespread processing methods

Dry or Natural processing

Photo credit: MTC Group

Process

This is the simplest and oldest cleaning method. Following harvesting, the coffee cherries are spread out on the ground or on a drying table to dry in the sun for two or three weeks while they are regularly turned over and the process of drying is controlled. As soon as the coffee cherries have sufficiently dried (their moisture content has dropped below 12%), the unwanted parts are removed by machines; in other words, they are hulled.

Territory

This method is used mainly in dry regions where water is scarce, such as Ethiopia, Brazil, Peru, and Indonesia.

Character

As the coffee beans are in contact with the fruit for a long period of time, the fruity flavours are more strongly present in these types of coffee. Fuller-bodied, more defined traits dominate in them.

 


Wet or Washed processing

Photo credit: MTC Group

Process

The coffee cherries are washed after harvesting, and their outer skin and the pulp are removed using machines. The partially cleaned cherries are placed into tanks filled with water where the coffee gets fermented due to the high sugar content of the mucilage that still covers the seeds. This process may last from twelve hours up to six days, until the gluey pectin layer can no longer be felt on the surface of the seeds. The coffee beans are rinsed with running water, then they are dried, and finally, the parchment skin gets also removed (hulled).

Territory

This is the most widely employed method, spread around the world. Since this method requires the use of significant amounts of water, this is connected to territories that abound in water.

Character

Due to fermentation, the coffee gets a more acidy character, and lighter flavours dominate in it. In the case of washed coffees the flavours of coffee varietals are more distinctive.


Honey processing

Photo credit: MTC Group

Process

The initial phase of the cleaning process is similar to that of the wet method. The coffee cherries are washed after harvesting, and the outer skin and the pulp are removed using machines leaving the mucilage on the seeds also called “honey” because of its sticky character. The coffee beans are subsequently dried, which involves a shorter period of fermentation. Depending on how long coffee is dried, the coffee beans receive different colours based on which yellow, red, and black honey coffees are distinguished.

Territory

This method is most widespread in Costa Rica, but recently it has also appeared in other Central American countries.

Character

"Honey" coffee shows much lower acidity than the washed version because it is fermented for a shorter period of time. Its flavour is sweet, but less full-bodied and complex than the natural type. Lighter roasting is recommended.

 

 


Pulped Natural or Semi Washed processing

Photo credit: Dennis Tang

Process

This is altogether very close to the washed process, but significantly less water is used for it. The coffee cherries are washed after harvesting, and the outer skin and the pulp are removed using machines. Then, skipping the fermentation step, the mucilage is also removed by machines designed specifically for this purpose. The process may vary in details, the coffee may also be dried with the pectin layer attached to it, and the coffee is cleaned only thereafter. The seeds are finally dried and the parchment skin gets also removed.

Territory

This method was developed in Brazil, where coffee is called "pulped natural" because of the use of machines removing the pectin layer, regardless of the exact procedure of the process.

Character

It has lower acidity compared to washed coffee, fuller-bodied, clearer, and simpler flavours dominate.


Giling Basah or Wet Hulled processing

Process

The coffee is washed after harvesting, and the outer skin and the pulp are removed using machines. Subsequently, it is dried as in the “honey” method, but for a much shorter period of time, for approximately one day. The partially dried musilage is washed off with water, and then, the drying continues until the moisture content is around 40-50 %. The semi-wet coffee is transported to central warehouses where it is hulled – this hulling process is called Giling Basah – as a result of which the coffee beans receive their greenish-blue colour that so typical of the method. At the end of the process, the coffee is completely dried and marketed.

Territory

Character

Jelleg

Lower acidity is coupled with fuller-bodied traits.


 

 

 

 

 

 


Fully Washed processing

Process

The process is carried out at washing stations where the coffee is transported by the producer right after harvesting. Firstly, the coffee cherries are put into tanks filled with water and the defective, floating pieces are filtered off. Subsequently, the outer skin and the pulp are removed using machines, and the coffee beans still covered in mucilage are ripened in dry tanks for about twelve hours, where they get fermented. After dry fermentation, the coffee is deposited in water tanks again where it rests for an additional twelve hours. Finally, it is washed off with clean water, sorted, and soaked for ten more hours. The process finishes off with drying for several months and hulling in the end.

Territory

The method is employed in Burundi and Rwanda.

Character

Smooth, light body, unique flavours typical of the region.

 


Monsoon Malabar processing

This method does not belong organically among cleaning processes, it can be rather defined as a curing process. The origins of the method date back to the times when coffee was transported from India to Europe with wooden sailing ships. During the nearly six-month long journey sailing the Cape of Good Hope was around the coffee was cured in the salty, moist vapour of the sea causing it to get lighter colour, loose its original acidity, and receive unique notes. Due to the development of transportation the curing of coffee was not possible in this way any more, therefore modern methods were implemented to replicate the same conditions.

Process

The coffee is processed using the dry method. The cleaned coffee beans are then put into large jute bags and hung up in huge, open buildings before the beginning of the monsoon season so as to be exposed to the moist, salty sea air. Approximately two months later, as the monsoon rains arrive, the coffee is spread out in thick layers on the floor of covered buildings. Due to the rainy season, the coffee beans absorb additional moisture, so they must be turned over and moved at regular intervals. At the end of the monsoon in September, the coffee is bagged again and marketed.

Territory

India, Malabar Coast.

Character

Seedy, earthy notes in addition to low acidity.