Welcome back to the Coffee Journey series! Today, we ask the question, what is coffee processing?
But first, a recap! From our previous blog, we outlined that coffee originated from its natural fresh form as a coffee cherry, grown from nurseries and harvested using either the strip or selectively picked process, once a year (or twice in some regions).
The next step in the process is drying which is carried out quickly after picking to prevent spoilage, using either the wet or dry method. Both are dependent on local resources such as access to land, water, climate conditions, weather and location.
Dry Method: age-old method used in countries where water resources are scarce. Freshly picked cherries are spread across large surface areas to dry in the sun, continuously raked throughout the day to prevent spoilage. During the night or when it rains, these cherries are covered to prevent them getting wet as moisture content must drop to 11%.
Photo: Racking Patio, Nicaragua
Wet Method: removes the pulp by putting the coffee cherries through a pulping machine so only the parchment skin of the cherry is left. The beans are then separated by weight as they pass through the water channels – heavier ripe beans sinking to the bottom while the lighter beans float. These are passed through drums & separated by size, and transported to large, water-filled fermentation tanks.
Photo: Kilimbi Washing Station, Rwanda
The beans will remain in these tanks, depending on the condition of the beans, the climate and the altitude, for 12 to 48 hours to remove the slick layer of mucilage (called the parenchyma) that is still attached to the parchment. While resting in the tanks, naturally occurring enzymes will cause this layer to dissolve.
When fermentation is complete, the beans feel rough to the touch. The beans are rinsed by going through additional water channels and are ready for drying.
The process the bean undergoes from picking to drying can vary depending on a number of factors, largely associated with the region of production; can all impact how the coffee cherry is processed, hence how flavours of coffee change from region to region.
There are many methods of coffee processing that are commonly used that will be outlined in the series. It is also noteworthy that these methods are not uniform across all regions and producers, which allows certain coffees to develop different aromas and flavours. Our team of experts meet with producers and suppliers so that they can fully understand the quality and flavour required for our customers but also educate our customers on the origins of the coffee, the people behind it and how to get the best coffee out of each bean.
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