To enter the specialty segment, coffee must score 80 or above during what is called cupping session. Washed coffee or wet processed coffee is well known for bringing home consistent and good results. Un-washed or naturally processed coffee on the other hand somehow usually doesn’t make the cut. Why is that?
Natural processing is the original processing method that has been going on for centuries. It uses less water, hence is more sustainable method. But what are the limiting factors behind the usually low scoring naturally processed coffee?
During wet processing the fruit or pulp that surrounds the coffee beans is removed early on and the when the beans are left to dry there is less medium for bacteria or fungi to come into play. Natural processing calls for drying the whole cherry. The skin, pulp and the beans altogether rest on the drying beds.
Fermentation is a natural process that happens due to bacterial and fungal activities. More material they have available to break (sugar/ fruit pulp), higher is the degree of care required to keep the cherries from going rot. Natural processing is best chosen in world regions having dry climate. Lesser the moisture in air and good is the availability of sunlight, natural processing is easier to be carried.
Naturally dried coffees have their unique fruity flavor and high sugar content that gets incorporated into the beans as the fruit pulp tends to surround the beans for longer period of time. Carefully naturally processed coffee can undoubtedly score high in cupping sessions.
But the risk of losing a good naturally processed lot is higher than wet-processed batch. Since, natural drying needs plenty of sun; the unpredictably changing weather patterns present a greater risk to natural processing. Unexpected rainfalls cause farmers to take emergency measures for drying coffee fruits on drying beds. Additionally, rain can increase the air moisture significantly afterwards, slowing the drying process and increasing the favorable conditions for mold.
To get a good cupping score from naturally processed coffee, few factors are available that can be played with. It is important to pick cherries that are well-ripe and pulpy or juicy to begin with.
Next come the drying patios, which must be clean and well-ventilated. Preferably the drying beds must be elevated so that wind may circulate better between the drying fruits. Coffee fruits must be hand sorted when out-laid on drying beds removing any rotten or unripe or defected fruits. Also the fruits must be spread evenly on the drying surface and must not remain heaped. Fruits should not overlap and must be stirred regularly to ensure even drying of pulp on every fruit. The smaller the batches are clustered together, the easier it is to manage them.
It takes about 20-25 days for coffee to dry and reach the point where retained moisture content of coffee fruits gets ideal. This moisture level is quoted 10.5%. Any higher and the sugar fermentation continues and take the cherry towards spoilage. Farms that best produce natural processed coffee use moisture-meter to keep the moisture content of cherries checked and don’t rely on guessing. Also, during drying, coffee isn’t left under blazing sun for entire duration of 20-25 days. After first few days (usually two-three) coffee is regularly dried beneath shade during the hottest points of the day.
When all is done, dried cherries, before they are hulled to get the beans from them, are stored carefully in moisture controlled environment, once again to protect against the mold.
While care is equally important in wet-processed coffee, natural processed coffee is more vulnerable to spoilage due to the presence of the fruit around the beans. The very factor gives it an edge over washed coffee giving it more complicated flavors, but smaller batches and crop yields that can be given individual care and attention are ideal for natural processing and not larger plantations where absence of such accurate care may lead to spoilage of entire stock.