Typical processing for sun-dried natural Ethiopian coffee sees cherries entering the washing station atop donkeys or carried by hand. Usually contained in a plastic bag at this stage, the cherries are weighed with a traditional scale (often painted a rich shade of sea green) and the volume entered against the producer’s name in the washing station’s logbook. The smallholder receives their money, which is used to purchase food and school supplies, and to pay for rent on their huts and small sections of land.
Once the cherries are logged, they are either carried straight to the drying table or—as we at Catalyst Trade prefer and pay premiums for—dumped into float tanks so that lower-density cherries can surface and be skimmed off for lower grade coffees or local consumption. The higher-density cherries sink to the bottom, displaying their quality by their weight. After this, the remaining cherries are carried in wood-and-wire trays to drying tables to let the water drip off of them and receive careful hand sorting of any visible defects.
At this stage in a typical natural process, the cherries will be moved to the beds, but for Low Oxygen Process, we add one more, very labor-intensive, step. The cherries are contained in custom-fit big blue barrels about as tall as an eight-year-old, and carefully sealed. What happens next is kind of like magic. As the coffees ferment, the carbon dioxide naturally off-gassed by the cherries pushes out the oxygen until the cherries are contained in a low oxygen environment for a carefully timed interval. It’s not just a clever name!
Many call this type of processing anaerobic or carbonic maceration, but we think of those misnomers since all fermentation occurs anaerobically and carbonic maceration refers to a very specific set of controlled processes that occur in a kind of wine processing and are not possible to replicate in coffee processing. Our Low Oxygen process tends to intensify the sweetness and fruit-forward notes in a coffee lot and amp up the clarity to the point of euphoria months later when it lands on the cupping tables of coffee roasters and the kitchen tables of lucky customers.
Post-fermentation, the cherries are carried to open-air drying tables that are shaded by mesh canopies and they laid out to slowly let the sun kiss them and draw out their moisture content. In a step up from usual table materials, the drying beds are made from nylon mesh instead of bamboo weave covered with jute. Once the cherries reach their ideal drying level, they are bagged up and kept carefully separate as they are transported first to a regional processing mill and then to Addis Ababa, Ethiopia’s capital, for final export processing and shipping to the world.