How does your coffee get processed?

After crude oil, green coffee accounts for the most heavily traded commodity in the world. Green coffee colour before roasting tends to range from dark raisin to dried chickpea colour, with taste profiles, for those with high perceptive taste buds, can also be wildly different.

This variety in taste comes from the different processing and fermentation methods used in the different coffee-producing regions, based on the weather conditions and water availability.

It is of little wonder to those with an acquaintance in winemaking that this other fruit also requires some use of chemistry.

With all the negativity associated with processing in the food world, it essentially means the necessary steps are taken, which also includes a certain degree of fermentation (yeasts and bacteria break down the sugars in the mucilage to yield acidic and fruit notes), to pull out the three successive layers covering the seeds to prepare it for shipping and later for roasting. These include the outer fruit or pulp, the sticky mucilage covering the seed in the middle and the parchment, or thin layer covering the seed.

As the user sense for taste has become more sophisticated, specialty coffee manufacturers see processing methods as a creative tool to bring in product differentiation be it accentuating fruit notes, sharpening or softening acidity, or fattening or lifting the body.

While experimentations are still underway, producers predominantly use three processing methods like the dry or natural (labor-intensive), washed or wet (water-intensive), and a newer hybrid called honey or semi-dry.

Natural or Dry Processed

Natural or dry processing is an age-old, traditional method of processing followed in Ethiopia, and other arid countries. This method accounts for 75-80 % of Ethiopia’s coffee production, requiring only small amounts of investment and labour.

Moreover, it requires only a meagre amount of rainfall and humidity which suits well with Ethiopian climate, known for its long, marked dry season that coincides with harvesting and processing.

With natural processing, coffee cherries are picked and sorted and simply allowed to dry out in the open in thin layers on the dry earthen ground, on woven mats, on tarpaulins, and even on the roadside.

If the moisture level is left unchecked, the dried coffee develops a white or greyish mold and there are chances of over fermenting into a boozy flavour.

Sidamo coffee beans are primarily but not exclusively dry processed.

Washed or Wet Processing

Wet processing is a relatively new method probably adopted in Ethiopia around the 1950s. It has gained acceptance only in recent decades, mostly practiced in areas with cool overnight temperatures and good sun exposure during the day.

In this process, pre-sorted, freshly harvested cherry is placed into separation tanks filled with water and then passed through a de-pulping machine, squeezing the seed out of the pulp. The depulping is done within 8-10 hours of the harvest. After de-pulping, the layer of sugary, viscous mucilage is left behind which is then allowed to ferment for half a day or up to a week.

The coffee producer in Ethiopia tries to moderate the time, temperature as well as the velocity of the fermentation process to avoid the risk of developing sour flavours. During fermentation, acids accrues to eat away the sticky mucilage.

After fermentation, the beans are washed multiple times and then immediately laid out in patios or drying beds. As the name suggests wet processing is a water-intensive processing style that results in a cup with a bright, clean taste.

The Hybrid Method: Honey or Semi-Dry Processed

Honey processing derives its name from the sweet mucilage and shares similarities as well as differences with both natural and washed coffee processing. In washed coffee processing while the coffee is removed from its fruit material as quickly as possible, for Honey processing, only the skin is fully removed, and the seed is allowed to dry while the sticky mucilage still clings on to them.

Drying time varies according to the weather conditions and the individual style of the honey process being applied, but it normally takes between two to three weeks for the coffee to reach 11% moisture.

For Yellow Honeys, coffee is shifted on tarp-covered patios under the full sun where it is spread into a thin layer for fast, even drying.

For something more fruity and fermented tasting such as red or black honey, the coffee is heaped in the greenhouse for some time before being agitated, rotated, aerated, and raked out.

During the drying time, the coffee ferments to develop characteristics that are unique to each Honey profile.

What Does This Mean to The End Consumer?

The inventors behind honey coffee helped discover the idea of experimenting with fermentation and processing once the producers shift focus from simply and expediently preparing seeds for roasting.

It is an especially exciting time for specialty coffee. Age-old techniques which greatly, at times accidentally, determine the taste of coffee, are finally adapting their formulas to produce a balanced, sweet yet sophisticated taste palette that deservedly reflects all the time, effort, and resources available for its creation.