After The Harvest: Green Coffee Processing Methods
Transforming coffee cherries into green coffee that is fit for roasting is a complex journey comprising several stages. The specific processing method utilized depends upon various factors, including the coffee's growing region, availability of water, desired flavor characteristics, and producer facilities.
Let's delve deeper to better understand the most frequently utilized processing methods and discover two experimental techniques that are rapidly gaining attention and generating unique coffee choices.
Natural Processing (Dry Process)
During natural processing, the entire coffee cherries are collected and left to dry under the sun or on raised beds. Over time, the cherries ferment by utilizing the natural sugars found in the fruit, with some being absorbed into the coffee beans. This process may take longer, sometimes stretching for 2-3 weeks, and demands frequent turning of the beans, as well as vigilant monitoring of humidity levels to prevent over-fermentation. Following drying, the dried pulp is removed to reveal the green coffee bean. Natural processing is prevalent in areas with restricted water access, such as Brazil and Ethiopia, and is renowned for producing coffee with fruity, wine-like flavors.
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Honey Processing
Honey processing also referred to as pulped natural in Brazil, combines natural and washed processing methods. During this process, some of the fruit is removed from the coffee cherry before drying, leaving a certain amount of mucilage on the bean. The coffee's honey color depends on the amount of mucilage left, with yellow honey having the least, red honey having more, and black honey having the most. Once the seed is dried, it is stored and hulled before shipment, revealing the green coffee bean. This technique is gaining popularity as producers experiment with different processing methods, and it results in coffee with a medium body and a sweet, syrupy flavor.
Explore Mercon Specialty’s Honey Process Specialty Coffee.
Washed Processing (Wet Process)
Washed processing is a widely utilized technique in regions of Central America, various parts of Africa, Colombia, and many other regions across the globe. Following the harvesting process, the cherries undergo pulping to extract the fruit from the seed, before being cleansed with water to eliminate any flaws or foreign substances. Following this, the beans are fermented in tanks for a specific duration based on the location and temperature to remove the mucilage. These beans, now referred to as "parchment," are then dried until they achieve a predetermined moisture level, either on raised beds, patios, or in large dryers, also known as "guardiolas."
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Wet Hulled Processing
The wet-hulled process, commonly referred to as Giling Basah, has found its origins in Indonesia and India, but has since expanded to other countries such as Vietnam's Mercon's Opal Bold. Through this process, coffee undergoes a thorough wash and fermentation process, eventually reaching the parchment stage. However, rather than allowing it to dry fully, the parchment is hulled midway through the drying stage, exposing the green bean. As a result, the coffee's flavors tend to be more earthy, with a heavy body and hints of roasted pepper.
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Embracing Experimental Fermentation Techniques
In recent years, experimental techniques have advanced, resulting in the development of two intricate processing methods that surpass others. Through fermentation, diverse flavor profiles can be achieved, and flavors can be enhanced in coffee. By prolonging the fermentation process from 48 to 120 hours, the same harvest can yield a distinctive flavor.
Anaerobic Fermentation
Anaerobic fermentation is a distinct processing method that complements traditional processes. This involves fermenting beans without oxygen and can be done after pulping, while still whole, or in conjunction with the normal washing process. The beans are kept in a sealed container for up to several days, and the duration of anaerobic fermentation determines the strength of the flavors. This technique, emerging in popular growing countries like Brazil, Guatemala, Honduras, and Vietnam, is known for its ability to produce sweet and aromatic notes, often resembling floral or candy-like flavors. For roasters and customers, experimenting with different fermentation techniques can yield distinctive and experimental flavors.
Explore Mercon Specialty’s Fermentation Green Coffees.
Yeast Inoculation Fermentation
The traditional fermentation process is now accompanied by a newer technique known as yeast inoculation, where specialized yeasts, commonly used in the brewing of wine or beer, are introduced to the fermentation tanks. Unlike the ambient air found in traditional methods, these yeasts take over the fermentation process, resulting in a more precise and controlled outcome. The range of flavors that can be produced through yeast fermentation is vast and offers limitless possibilities. This contemporary approach to processing has gained traction in various regions such as Brazil and Costa Rica.
The flavor profile of raw coffee beans is largely determined by the processing method used after they are harvested. The specialty coffee industry is known for its enthusiasm for exploring different processing techniques to create exceptional and diverse flavors that cater to coffee enthusiasts globally. At Mercon Specialty, we proudly offer an extensive collection of coffees sourced from various regions worldwide, all of which are processed using a range of distinctive methods.
Explore our specialty coffee collection or contact us for guidance in discovering exceptional coffee!