Coffee processing represents one of the most crucial stages in determining a coffee’s ultimate flavor and quality. Coffee processing is the series of steps between picking a ripe cherry at the farm and preparing the green bean for export to our roastery. This journey from fruit to stable green bean involves precise coordination of multiple stages, each with its own technical requirements and quality considerations.
Careful selection of red cherries at harvesting is essential for good quality coffee. Cherries should be processed the same day as harvesting and should not be mixed with the previous day’s harvest. The quality foundation is established immediately at harvest, where timing and selectivity determine the raw material quality for all subsequent processing steps.
Harvest and Initial Handling
The processing chain begins with harvest methodology, which fundamentally impacts downstream quality. As not all coffee beans mature at the same time, selective picking ensures that only the red cherries are harvested, and any unripe fruit is left to further develop. This is usually the preferred method for the finer Arabica variety, but it is a more labour intensive and a costly process. Professional producers understand that if the cherries are harvested too green, the coffee will be sour, and if they are overripe, the beans may ferment and spoil the flavour of the final brew.
Once the fruit has been harvested, it must be processed quickly to prevent oxidisation as it can impair the flavour. This urgency creates the first critical control point in the processing chain. Equipment and sorting areas should be checked daily and kept thoroughly washed clean. Any fermented part of cherry from the previous day will contaminate the newly harvested cherries and result in deteriotation of the entire batch.
Quality control begins immediately with cherry sorting. The process begins with meticulous sorting to remove any underripe, overripe, or damaged cherries. Better sorting at the farm means higher consistency in our roastery, as defective fruit is a primary source of off-flavours. Professional facilities implement multiple sorting stages, combining visual inspection with density separation using water channels.
Primary Processing Methods
Coffee processing diverges into distinct pathways that fundamentally alter the final bean characteristics. The three primary methods—washed, natural, and honey processing—each follow different approaches to removing the fruit layers surrounding the coffee seed.
In washed processing, the skin of the fresh cherry is physically removed using a pulper machine with addition of water (pulping). The sugar coating (mucilage) is allowed to ferment over one to two days and then the parchment is washed thoroughly to remove all traces of fermented mucilage. This method requires substantial water resources, with large quantities of water (between 2 to 10 L water per kg of fresh cherry) and requires very good management of the fermentation and washing process to ensure the coffee flavour is not damaged in the proces
Natural processing takes a fundamentally different approach. The natural, or dry process, involves drying coffee cherries in the sun by either being left on the tree, on patios or on raised beds. It is a very labour intensive process which requires workers to constantly turn the cherries and be vigilant for mould. The drying phase is critical, as this can last 3-4 weeks. Drying cherry coffee may take 18 to 20 days.
Honey processing represents a middle ground between these approaches. Honey processing removes the cherry skin but leaves a specific amount of the sticky mucilage on the bean during drying. These lots, often from Costa Rica or El Salvador, strike a middle ground. They offer more sweetness and body than a typical washed coffee but retain more clarity than most naturals.
Controlled Drying and Moisture Management
Regardless of processing method, achieving proper moisture content represents a critical quality checkpoint. Coffee is fully dry when green bean is a translucent, jade green colour and 12% moisture content. This moisture target is universal across processing methods, though the time required varies significantly.
Parchment coffee dries in about 9 to 10 days. During the precess, coffee must be covered with polythene or plastic sheets if rain occurs and every night to stop re-wetting that results in mould development. Environmental control becomes paramount during this phase, as over-dried coffee is easily damaged during hulling and may also result in a bland flavour in the final cup.
Proper drying technique requires constant attention. The processor needs to rake the green coffee beans 2–3 times per hour to ensure a safe drying process. This intensive labor requirement reflects the delicate balance between achieving target moisture levels while preventing fermentation or mold development that could compromise the entire lot.
Dry Milling and Quality Preparation
Once dried coffee reaches stable moisture levels, it enters the dry milling phase, which transforms parchment coffee into export-ready green beans. Dry milling is a pivotal stage in the coffee processing chain that takes place after coffee producers have picked and dried their coffee using several unique processing techniques. At this stage, the parchment coffee (coffee beans still encased in a protective husk) undergoes hulling, grading, and sorting before export.
The hulling process represents a critical mechanical step. The huller removes the parchment surrounding the coffee beans and reveals the green bean. However, hulling is the removal of what is left of the fruit from the bean, whether it is the crumbly parchment skin of washed coffee, the parchment skin and dried mucilage of semi-washed coffee, or the entire dry, leathery fruit covering of the natural processed coffee.
Following hulling, beans undergo comprehensive cleaning and sorting. This part of the dry mill removes every last bit of unwanted material. Only clean coffee beans proceed to the next step. Cleaning itself is a three-part process consisting of pre-cleaning, the magnet, the destoner. Modern facilities employ sophisticated equipment including machines blow the beans into the air; those that fall into bins closest to the air source are heaviest and biggest; the lightest (and likely defective) beans plus chaff are blown in the farthest bin. Other machines shake the beans through a series of sieves, sorting them by size.
Grading, Quality Control, and Export Preparation
The final stage before export involves comprehensive quality assessment and standardization. Coffee beans are meticulously screened and sorted by size using screens with precisely measured holes (measured in 1/64th of an inch). These screens, numbered from 8 to 20, allow buyers and roasters to select beans that will roast evenly and produce consistent results. Larger beans (typically screen sizes 15-18) aren’t necessarily better, but consistency in size is crucial for even roasting.
Professional grading systems evaluate multiple parameters simultaneously. Perhaps the most critical aspect of physical grading is defect analysis. Trained graders meticulously inspect samples for primary and secondary defects The industry standard requires that for coffee to be graded as specialty, its sample must contain zero primary defects and less than five secondary defects. This represents an extraordinarily high standard when considering that in 12 oz, you will get around nine hundred coffee beans.
Quality assessment extends beyond physical defects to include sensory evaluation. The coffee cupping score developed by the Specialty Coffee Association goes from 0 to 100, and only coffees scoring 80 points or above get the “specialty coffee” badge of honor. Commercial-grade coffee scores anywhere from 60 to 80. This comprehensive evaluation system ensures that grading directly impacts farmer income, with higher grades commanding premium prices—sometimes 2-3 times more than commercial-grade coffee.
The final export preparation involves careful packaging and storage considerations. Green coffee beans are “hygroscopic” meaning they absorb what’s around them — mostly moisture. Out on the open seas there are radical environmental changes that can compromise the coffee beans during transport. For this, green coffee is packed in hermetic, heavy gauge, “GrainPro” bags that help maintain moisture stability as well as keep out harmful insects and pests.
Understanding this complete processing chain reveals the remarkable complexity behind every cup of coffee. Each stage represents critical decision points where technical precision, quality control, and market considerations converge to transform a simple fruit into one of the world’s most valued agricultural commodities.