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Coffee processing: the flavours of processing

Each processing brings remarkable changes to the coffee beans, enriching them with aromas and scents. Unique aromatic notes depending on the variety processed: discover natural, washed and honey coffee.

Barbara Fassio
Barbara Fassio

Green coffee beans do not have strongly marked aromas; it is the roasting process that enriches the raw material, creating the various volatile compounds that make coffee smell unique. When green coffee is roasted, the beans produce more than 800 aromas. These have a profound impact on the perception of coffee flavour and can often be used to determine its origin, roasting profile and freshness.

What we perceive as flavour is often actually an aroma: the tongue only perceives the tactile sensation of the body and tastes (sweet, bitter and sour mainly). When these combine with the aroma perceived by the receptors of the nose, we get the flavour. This is indeed enhanced by roasting, but it is formed in all the previous stages of bean processing. Every action of the producer, the roaster and finally the barista, no matter how small, has an impact on the cup of coffee you are drinking: now let us try to understand how much of an impact the processing of green coffees made on the plantation has.

Different coffee processing

Processing is simply the method used to remove the coffee seeds, or beans, from the pulp and skin. Following the harvesting of the cherries, the producers begin a series of steps that have a significant impact on the final flavour.

There are essentially two steps: the removal of the different layers of the cherries and the drying of the beans. The order in which these activities take place is what distinguishes the main processes: washed and natural. Nowadays, a host of other innovative processing methods are emerging, many of which impart unique flavours to coffee. 

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Using the natural method, the beans are dried entirely, with the skin and pulp intact. This preserves not only the sugars in contact with the bean, but also the acids and phenols, components that contribute to the characteristic taste and flavour of each fruit. When whole coffee beans are dried, the compounds inside the skin continue to ferment.

The washing process, on the other hand, involves removing all residues from the skin and pulp before the coffee is dried. Honey processing is a middle way, in which the skin of the fruit is removed before the beans are dried, while almost all the pulp remains attached. The layer of mucilage that is retained and fermented makes the beans sticky (hence probably the name honey) and will influence the taste of the coffee.

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The processing method makes a difference to the flavour and aroma, because the sugars in the pulp left on the natural or honey beans undergo changes that significantly alter the chemical composition of the green beans. These reactions create sweetness and body in the final cup. Natural coffees are in fact sweeter than washed coffees largely due to the fermentation of the sugars in the pulp: natural beans will have more intense, complex and distinct flavours than any other processing method. 

Both washed and natural coffees undergo fermentation, but in washed coffees there is much less material for the enzymes to work on because the pulp has been removed. The enzyme action thus creates fruity, floral and caramel notes that you can enjoy in the cup. On the other hand, washed coffees are cleaner and allow you to taste all the nuances of the origin and variety of the beans. Washed coffee beans may be more lacking in strong and complex flavours than natural ones, yet they are so delicate and light-bodied that they are enjoyable at all hours of the day.

Honey processing, on the other hand, due to the removal of the cherry skin, allows better fermentation of the mucilage around the bean. This results in an even more pronounced sweetness than that of natural coffees, with more buttery aromas and notes of dried fruit. The honey gives a stronger flavour than washed beans, but is more balanced than natural processing.

Fermentation can make a big difference in terms of flavour, aroma and body, but must be carefully controlled. Excessive fermentation can create too many acetic acids or phenolic compounds, which make the final cup bitter or sour: this is where the skill of the producer comes into play!

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The infinite mixes that can be created by combining different varieties of coffee and different processing choices allow you to play with taste: trying the same coffee, processed differently by the producer, is an experience that we recommend you do as soon as possible!

Each processing method has its advantages and no approach can be considered superior to the others; the skill of the producer lies precisely in knowing his beans and choosing the most suitable processing for them.

Taste, taste and taste again … only then will you find your favourite combination!