Finca Silencio: How is Coffee Dried?
You probably don’t think about how your coffee was dried when enjoying your morning cup, but it is one of the determining factors that affect the coffee’s taste. Although the unique flavor is more noticeable in specialty coffee, each coffee is different and carries a unique set of flavor properties.
The process starts right after the coffee cherry is harvested. The purpose of drying the beans is to safely reduce the humidity of the coffee in a timely manner. The humidity needs to be reduced from 100% to 11% to prevent the growth of mold and bacteria. The process starts right after the coffee cherry is harvested.
If the humidity is not reduced from 50% to 11.5%, serious issues arise in less than three days. Farmers and exporters could find themselves with the presence of Ochratoxin, a chemical substance formed by Aspergillus and Penicillium fungus. Ochratoxin is nephrotoxic and can cause serious health conditions, including liver disease.
Was Your Coffee Naturally or Artificially Dried?
It is important to differentiate the parchment color of the bean as this tells us how the coffee was processed! Artificial drying depends on implementing an additional heat source, like propane, electricity, coal, or the coffee itself (resulting from removing the parchment from the naked bean). The problem with using these fuels is the chemical reaction that happens with the coffee and the carbon gasses mixing.
Carbon monoxide and carbon dioxide can impart an unpleasant flavor. This chemical change alters the flavor and integrity of the coffee and is noticed in coffee tastings. Professional tasters and coffee graders prefer sun drying methods though they are much more labor-intensive, especially in challenging climates.
A region’s climate significantly impacts how coffee producers dry their beans. In areas with low humidity, sun drying methods can be done with ease and cost-effectiveness, though this is not the case in regions with daily showers and high humidity.
Coffee Drying On Finca Silencio
In Colombia and other tropical coffee-growing regions, the process of drying often coffee comes with challenges. For this reason, the coffee drying process requires adapting to what the changing climate offers and implementing alternative coffee drying strategies to face challenges!
Our farm, Finca Silencio, is located in the heart of the coffee region. At an altitude ranging from 1800-1850 meters above sea level, Finca Silencio has the best conditions for growing specialty coffee; A matrix of sandy-loam soils with a high content of mineral-rich volcanic ash and a thick layer of organic matter. These rich soils allow for the easy development of any species of flora, both herbaceous and woody.
On Finca Silencio, we use the parabolic dryer (marquee). This structure is made with finely crafted pine that is used as a base and is structured similar to that of a raised greenhouse using plastic to cover the marquee. The plastics greenhouse effect allows the inside temperature of the dryer to be raised to approximately 40ºc. This temperature is optimal and aids in extending the conservation time the coffee is stored. This is due to a uniform semi-forced drying effect that reduces humidity from the center of the bean.
The parabolic method allows the coffee bean to dry naturally making it a sustainable form of drying coffee that does not use an external carbon source. The plastic cover of the dryer blocks incident solar rays. This gives the bean a parchment color with a tone of greenish-blue hue. In contrast, artificially dried coffees are paler and yellowish.
The cohesion force makes residual water drop (obtained from washing the coffee), wrapping the bean uniformly, and thus causing a thin layer of water to form over the bean. This condition permits water to evaporate at its dew point. Therefore, we don’t need the pressure point temperature to evaporate water, but with the 40ºc and two scrambles a day we have enough heat to make the phase transfer possible among the entire coffee bean in a matter of three to seven days depending on the season (sunny or rainy).
Keeping green coffee stored in the proper facilities and using the right equipment is a key factor in correctly and safely drying the beans. Using improper storage facilities that are not humidity controlled can damage and potentially waste a hard-earned harvest. Fungus and bacteria threaten the quality and safety of the coffee. For this reason, when roasters are buying their green coffee, they should ask the question, who handled and dried these beans?
It is important coffee roasters understand and fully appreciate the labor and process of producing each bean.
On our farm, we use 5 marquee dryers that add up to 1600 square feet. With additional humidity-controlled units so we can monitor the humidity remotely. The science of drying coffee is more complex than meets the eye. There are several physical factors all in play that can drastically make a difference in the final product.
All these factors that go in the coffee drying process may seem minor to consumers but we can assure you they make all the difference!