Wet Processing the Coffee Bean

Wet Processing the Cherry (Coffee Bean)

Wet Processing

This system is much more expensive, due to far greater requirements of equipment, labor, time and water. Before any fermentation can begin in the freshly picked cherries, they are immediately washed in large tanks from which the water carries them into a system of channels. Staying in contact with the fresh-flowing water helps to loosen the outer skin, while the cherries are carried towards a de-pulping machine. Here they lose their skin and some of the pulp, but the flowing water takes the beans, still wearing their parchment covering and a lot of the sticky mucilage, through various screens, sieves and sluices, which further sort the beans by size and weight.

At last the beans arrive in a fermentation tank, where any remaining mucilage is broken down by natural enzymes during a 36-hour soak. The fermentation is monitored and controlled, as it must only remove the mucilage and not develop off-flavors in the beans themselves. The parchment beans, once clear of mucilage, are rinsed, drained and spread out on patios or wire-mesh platforms, and left to dry in the sun.

As the dry method, the parchment beans are turned and raked for between one and two weeks, or they may go into low-temperature drying machines, until their moisture content is about 11-12 percent: the last stages are critical because over-drying makes them brittle and they can lose quality; under-drying means vulnerability to unwanted fermentation, fungi and bacteria or bruising during subsequent hulling. Parchment beans are stored for about a month, and can be stored for several months in a controlled atmosphere. When exportation is imminent, the beans are taken to the curing mill where the parchment is removed by hulling, and the washed beans undergo the same processes as do the dry-processed beans.


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