Stand at the edge of our wet mill station in Holualoa during peak harvest season and your senses fill up fast. The air carries the sharp, almost cidery scent of coffee cherries that have just come off the tree. Water moves through the pulping channel with a steady, rhythmic rush. If you pick up a ripe cherry and press it gently between your thumb and forefinger, the seed inside pushes through the skin like a small, slippery stone. That moment, that tiny act of squeezing a cherry, captures the entire premise of wet milling. There is a bright, dense seed inside a sugar-rich fruit, and the job of the wet mill is to separate the two with as much care and precision as possible.
Most of the visitors who come to Buddha's Cup have already tasted great Kona coffee. Far fewer have watched it become great. They know the cup. They may not know the channel, the fermentation tank, the drying bed, or the resting bin. The journey from ripe red cherry to the clean, stable green bean that eventually reaches your grinder is where processing method makes all the difference. And wet milling, also called the washed process, is the method that defines the flavor profile Kona coffee is celebrated for around the world.
This article walks through every stage of wet milling as it happens on a working Kona farm. We explain what each step does, why it matters, how skilled operators make real-time decisions at each stage, and how the unique geography and climate of the Kona Coffee Belt make this process distinct from wet milling anywhere else on earth. If you have ever wondered what happens during a Kona coffee farm tour and what all those tanks and channels actually accomplish, this is your complete answer.
We grow both Kona coffee and mamaki tea here on our farm in Holualoa, and we process our own coffee on-site. We have guided thousands of visitors through these same steps during farm visits. Everything described in the pages below reflects the real, hands-on work of a small working farm in the heart of the Kona Coffee Belt, not a textbook abstraction. We hope it brings your next cup a little more meaning.
What Is Wet Milling and Why Do Kona Farms Use It?
Before we walk through the steps, it helps to understand what wet milling actually is and why it became the dominant processing method for high-quality Kona coffee. The word "milling" can be confusing because it suggests machinery and mechanical force, and while machinery is involved, water is the defining element. Wet milling uses water throughout the process to sort, transport, ferment, and wash the coffee seed, distinguishing it sharply from dry processing methods where water plays almost no role at all.
Wet Milling Defined
Wet milling, also known as the washed process, is a post-harvest coffee processing method in which the outer fruit layers of the coffee cherry are removed using water and mechanical equipment before the seed is dried. The goal is to strip the seed of the cherry skin, the fruit flesh, and the sticky mucilage coating, leaving only the seed enclosed in its thin parchment shell, which is then dried down to a shelf-stable moisture content.
The contrast with dry processing, also called the natural process, is significant. In dry processing, the whole cherry is harvested and laid out to dry intact. The seed absorbs sugars and compounds from the fermenting fruit as it dries over weeks, which produces a heavier, fruitier, often wine-like cup character. Many coffee drinkers love natural process coffees for exactly that quality. But dry processing introduces variability. The fruit is drying unevenly, different parts of the batch ferment at different rates, and without water sorting at the beginning, damaged or underripe cherries often move through the process alongside quality fruit.
Wet milling addresses all of those variables. By removing the fruit early and using water at multiple stages to sort and clean the seed, the washed process isolates the inherent character of the seed itself. The resulting cup is cleaner, brighter, and more consistent batch to batch. For a region like Kona, where the soil, elevation, and microclimate produce a distinctive terroir-driven flavor, wet milling is the method that lets those terroir qualities speak without interference from fruit processing variables.
Why the Washed Process Suits Kona Coffee's Flavor Identity
Kona coffee has earned its reputation through a combination of factors that begin underground and extend through every layer of the growing environment. The Kona Coffee Belt runs approximately 20 miles along the western slopes of Hualalai and Mauna Loa volcanoes on the Big Island of Hawaii, sitting between roughly 1,000 and 3,000 feet in elevation. The volcanic soil in this zone is rich in minerals, well-draining, and deeply fertile. Holualoa, where our farm sits, is squarely within this belt, at an elevation where the mornings arrive sunny and warm and the afternoons bring gentle cloud cover that moderates heat and slows moisture loss from the soil.
This microclimate creates what coffee professionals describe as a slow, even ripening cycle. Cherries take longer to reach full maturity in Kona than in many equatorial growing regions, and that extended time on the tree allows the seed to accumulate a wider range of sugars, acids, and aromatic compounds. The resulting flavor profile is complex: medium body, balanced acidity, with notes that range from floral and fruity to nutty, chocolatey, and subtly wine-like depending on the lot and the roast.
Wet milling amplifies these terroir-driven characters rather than layering additional processing flavors over them. When you strip the fruit early and wash the seed clean, you are essentially giving the seed's own inherent compounds the clearest possible path to the cup. The volcanic minerals that influenced the cherry's development, the slow sugars that built up over weeks of cloud-kissed ripening, all of that shows up clearly in a washed cup in a way that might be obscured by the heavy fruit notes of a natural process.
It is worth noting that not every Kona farm uses wet milling exclusively. Some producers experiment with honey process, where a portion of the mucilage is left on the seed during drying, or even full natural process to explore different flavor expressions. But washed remains the regional standard for high-grade Kona coffee, and it is the method most strongly associated with the flavor profile that has made Kona one of the most recognized coffee origins in the world. You can also learn more about how volcanic minerals influence Kona coffee flavor to understand how the soil interacts with every stage of cherry development before the fruit ever reaches the wet mill.
The Farm-Level Advantage of Running Your Own Wet Mill
Many small coffee farms, particularly in regions where wet milling infrastructure is expensive or impractical to build, send their harvested cherries to a centralized wet mill that serves multiple growers. This arrangement has economic logic, but it comes at a cost to traceability and quality control. When your cherries mix with cherries from other farms at an outside facility, your ability to monitor each stage of processing is essentially gone. You may receive green beans back that have been processed competently, but you cannot guarantee that your harvest was handled at the precise timing, temperature, and care level that your quality targets require.
Running an on-site wet mill means every decision, from the moment cherries enter the flotation tank to the day parchment coffee goes into conditioning storage, is made by people who know this specific farm, this specific harvest, and this specific standard. It is a significant investment of infrastructure and skilled labor, but for a farm committed to producing traceable, high-quality Kona coffee, it is the only approach that makes full sense. The legacy of Kona coffee farmers who have maintained this level of hands-on stewardship is exactly why the region's reputation has endured for generations.
With that foundation in place, let us walk through the process step by step, the way it actually unfolds on a working farm from the first moment a cherry leaves the tree to the day a stable, beautifully processed green bean is ready for roasting.
Step 1: Cherry Harvest and Intake
Wet milling does not begin at the machine. It begins at the tree. The quality of the finished green bean is shaped more by harvest decisions than by any single processing step, and no amount of skilled wet milling can fully compensate for a poorly executed harvest. This is why experienced Kona farmers treat picking not as a preliminary task but as the first critical stage of the entire process.
Selective Hand-Picking on the Kona Slope
On a quality Kona farm, cherries are picked by hand, one by one, selecting only fruit that has reached full red ripeness. This is called selective picking, and it is labor-intensive in a way that mechanized strip harvesting simply cannot replicate. A strip-harvested tree yields everything attached to the branch, ripe cherries, underripe green cherries, overripe purple or black cherries, and dried fruit that never fell off. A selectively picked tree yields only the cherries that belong in the wet mill right now.
Why does ripeness matter so much at this stage? An underripe cherry contains seeds that have not yet fully developed their sugar and aromatic compound profiles. Those seeds will process and roast differently from ripe seeds, and the astringent, grassy, or woody flavors of underripe coffee are persistent. They do not roast out cleanly. An overripe cherry, on the other hand, has already begun breaking down on the tree. The fruit flesh is beginning to ferment in place, and that uncontrolled pre-harvest fermentation creates sour, winey, or musty compounds that follow the seed through the wet mill and into the cup.
The Kona Coffee Belt's geographic and regulatory protections give producers an additional incentive to maintain these standards. The Kona designation is restricted to coffee grown in a specific zone on the Big Island, and the reputation of that designation, and the premium pricing it commands, depends on the collective quality of farms producing under it. For visitors who want to see selective picking in action, our Kona coffee farm tours during harvest season offer a chance to walk the rows and understand what the picker's eye is actually evaluating at each tree.
Pickers on a Kona slope work efficiently but carefully, moving through rows and returning to the same trees multiple times as the season progresses because cherries on a single tree do not all ripen simultaneously. This "pass" system means a productive Kona farm may send picking crews through each section of its orchard three to five times over the course of the harvest season, which on the Big Island typically runs from late summer through early winter.
Cherry Intake and the Flotation Sort
Cherries arrive at the wet mill station and go immediately into the first processing step: the flotation tank, sometimes called the receiving tank or simply the water channel. This step takes advantage of a simple and reliable physical property. Dense, properly developed cherries sink. Underdense cherries, including those that are underripe, overripe, hollow, or damaged by the coffee berry borer insect, float.
The flotation sort is elegant in its simplicity. Workers dump freshly picked cherries into a tank of clean water and observe. The sinkers, the good cherries, settle toward the bottom or rest low in the water column. The floaters rise immediately to the surface and are skimmed off, separated, and either composted or processed separately at a lower quality designation. The sinkers continue downstream to pulping.
This flotation step is the first quality gate of wet milling. It does not replace careful selective picking, but it catches what selective picking might miss, particularly insect-damaged cherries that look intact from the outside but have hollow or compromised seeds inside. Even on a farm that picks as carefully as possible, the flotation sort will reveal a small percentage of floaters in every batch. Catching them here, before they enter the pulper and mix with the premium lot, is a critical protection of the finished product's quality.
Why Speed Between Harvest and Processing Matters
Coffee cherries are living biological material, and once they leave the tree, biological processes begin immediately. The fruit begins to ferment from the moment of picking, driven by naturally occurring microorganisms on the skin and in the air. This is not necessarily a bad thing in controlled conditions, but it becomes a serious problem when cherries sit for many hours or overnight before processing begins.
Uncontrolled pre-processing fermentation in a pile of harvested cherries creates musty, alcoholic, vinegary, or putrid off-notes that penetrate the seed through the fruit skin and mucilage. These flavors are stubborn. They persist through washing, through drying, through roasting. The cup will carry them. For this reason, best practice on a working farm is to process freshly picked cherries the same day they are harvested, or within 12 hours at the most. On a farm with its own wet mill on-site, this timeline is achievable because the gap between picking and processing is measured in minutes to a few hours rather than in transportation time and scheduling.
The speed requirement is another argument for the farm-scale wet mill. When a farm must transport cherries to an off-site processing facility, same-day processing is not always possible. When the mill is on the farm, the picker and the pulper are neighbors, and the freshness of the cherry when it enters the water is never in question.
Step 2: Pulping
Once the flotation sort has separated the dense, quality cherries from the floaters, the sinkers move to the pulping machine. Pulping is the mechanical heart of wet milling. It is the stage where the coffee cherry transforms from a whole fruit into a coffee seed wrapped in parchment, stripped of its skin and most of its fruit flesh, and ready for fermentation.
What the Pulping Machine Does
The pulping machine uses rotating drums, discs, or breast plates, depending on the design and manufacturer, to grip the outer skin of the cherry and pull it away from the seed. The cherry skin, called the exocarp, tears open and is stripped off. Most of the fruit flesh, called the mesocarp, comes away with it. What emerges from the pulper is the coffee seed still enclosed in its thin parchment layer, which is a papery membrane that is part of the seed's natural anatomy, with a coating of sticky, sugar-rich mucilage still clinging to the parchment's outer surface.
That mucilage layer is important to understand because it drives the next step. The pulper removes the skin and most of the fruit, but it cannot remove the mucilage. The mucilage is a pectin-rich gel that bonds tightly to the parchment. Removing it requires either enzymatic breakdown through fermentation or mechanical scrubbing in a demucilager. On most artisan Kona farms, traditional tank fermentation is the method of choice, and the pulper's job is to deliver a clean, skin-free, mucilage-coated parchment seed to the fermentation tank.
Coffee seeds come in two main forms. Most coffee cherries contain two seeds that develop facing each other, producing the flat-faced seeds we typically think of as coffee beans. Occasionally, a cherry develops with only one seed, which grows round rather than flat because it has the entire interior space to itself. These are called peaberries. If you have ever wondered about Peaberry Kona coffee, this is the origin of the term. Peaberries roll differently through pulpers and behave differently in the roaster, which is why they are often sorted separately and sold at a premium.
Pulping Settings and Their Effect on the Bean
The pulping machine is not a set-and-forget piece of equipment. Its clearance settings, the gap between the rotating drum and the breast plate that together grip and strip the cherry, must be calibrated carefully and monitored continuously during operation. The optimal gap depends on the size of the cherries being processed, and cherry size on a Kona farm varies across the harvest season and across different sections of the orchard depending on tree age, microclimate, and nutrition.
If the clearance is set too tight, the machine nips and cuts the seeds. These mechanical defects create chips and cracks in the parchment and seed that lead to uneven roasting, scorching at the damaged edges, and bitterness in the cup. If the clearance is too loose, whole cherries pass through the machine without being pulped at all, which means they carry their fruit intact into the fermentation tank, where they create flavor and consistency problems for the entire batch.
Skilled operators check the output of the pulper frequently during a processing run, pulling samples from the channel after the machine, feeling the seeds, and looking for signs of nicking, skin fragments mixed with the seeds, or intact cherries that slipped through. Adjustments are made on the fly based on what the sample shows. This is hands-on craft work, not automated quality control, and it is one of the many reasons why experienced wet mill operators are so valuable on a small Kona farm.
The pulp byproduct, the stripped cherry skins and fruit flesh, does not go to waste on a well-run farm. It is composted along with other organic material and worked back into the orchard soil, closing the nutrient loop and reducing the farm's reliance on imported inputs. This practice reflects the kind of whole-system thinking that sustainable agriculture on a small Hawaiian farm requires.
Moving Pulped Beans to Fermentation Tanks
After the pulper, beans travel by water channel to the fermentation tanks. The same water that served as flotation sorting medium is part of this transport system, moving beans through gravity-fed channels from one station to the next. As beans move through the channel from pulper to fermentation tank, a brief secondary density sort sometimes begins to happen naturally. Lighter, less-developed seeds begin to separate from denser, heavier ones under the influence of water flow and gravity. This separation will be refined further in the washing channel after fermentation, but the process begins here.
The fermentation tank is where the most time-sensitive and skill-dependent work of the entire wet mill process takes place. Getting fermentation right is what separates an extraordinary Kona lot from a merely good one, and it is worth spending considerable time understanding exactly what is happening in that tank.
Step 3: Fermentation
Ask a casual coffee drinker what fermentation does to coffee, and they will likely imagine something like wine or beer, alcohol, bubbles, the transformation of sugar into something intoxicating. The truth of coffee fermentation is more subtle and more interesting than that, and understanding it is essential to understanding why wet milling produces the cup character it does.
What Fermentation Is Actually Doing
Remember the mucilage layer that the pulper leaves behind on the parchment surface. That mucilage is a pectin-rich gel, and pectin is a structural carbohydrate that is not water-soluble. You cannot rinse it off. You cannot rub it off with a cloth. It bonds to the parchment with enough tenacity that mechanical scrubbing at the pressure levels available in a small farm wet mill would damage the parchment and the seed beneath it.
What does dissolve pectin is pectinase, a class of enzyme that breaks down pectin's molecular structure. Fermentation produces pectinase. Specifically, the naturally occurring bacteria and wild yeasts that are present on the cherry skin, in the water, and in the ambient air of the fermentation environment colonize the mucilage surface and begin metabolizing the sugars in that mucilage layer. As they do, they produce pectinase enzymes as metabolic byproducts, and those enzymes digest the pectin matrix of the mucilage, breaking it down from a gel into a liquid that can be rinsed away with water.
So the goal of fermentation in the wet mill context is not to add alcohol or fruit flavors to the coffee seed. The goal is to generate enough enzymatic activity to dissolve the mucilage. The microbial communities doing this work are real and varied, including species from the Lactobacillus, Leuconostoc, and Erwinia families among others, but they are functioning as biological machinery for mucilage removal rather than as flavor-builders in the way that fermentation works in brewing or winemaking.
That said, fermentation does influence flavor. The length, temperature, and microbial composition of the fermentation environment all affect what compounds make it onto the parchment surface and potentially into the seed. Carefully managed fermentation contributes subtle complexity to the finished cup. Poorly managed fermentation introduces off-notes that cannot be removed downstream. This is why experienced operators treat the fermentation tank with the same respect a winemaker gives to the fermentation vessel. If you are curious about how coffee cherries get fermented on-site at a farm like ours, the answer is in tanks just like these, monitored carefully across the full fermentation window.
How Long Fermentation Takes and How Operators Know It Is Done
The duration of fermentation is one of the most variable and judgment-dependent aspects of wet milling. Under the conditions typical of a Kona farm, fermentation generally takes somewhere between 12 and 48 hours. The wide range reflects the influence of ambient temperature, altitude, water chemistry, the size and health of the microbial community in the tank, and the initial sugar content of the mucilage, which varies with cherry ripeness and variety.
Holualoa's elevation and mild climate create a relatively stable fermentation environment compared to farms in more variable growing regions. Temperatures are moderate, rarely swinging into extremes that would accelerate fermentation dangerously or stall it into an incomplete state. This consistency is an advantage. Operators working in the Kona microclimate can develop reliable intuitions about their fermentation window based on accumulated experience with their specific location, their specific water source, and the particular harvest year's cherries.
But intuition is always backed by physical testing. The classic and most reliable method for assessing fermentation completion is tactile. An experienced operator reaches into the fermentation tank every few hours and takes a handful of beans. They rub those beans vigorously between their palms. When mucilage is still present, the beans feel slick, almost soapy, and they clump together. As fermentation progresses and mucilage breaks down, the texture changes. The beans begin to feel rough, almost like wet gravel or coarse sandpaper. They no longer stick to each other. When that rough, granular texture is consistent throughout the sample, fermentation is complete and the beans should come out of the tank immediately.
Over-fermentation is a serious risk. If beans sit in the tank after mucilage has broken down, the microbial communities continue to work on whatever substrate remains, including compounds on and in the parchment. The result is vinegary, overly sour, funky, or alcoholic flavors that are essentially baked into the seed at a chemical level. These flavors survive roasting. They appear in the cup as defect notes that undermine the coffee's quality and can make an otherwise excellent Kona lot unsaleable at premium prices. Under-fermentation is equally problematic in a different way. Residual mucilage on the parchment creates uneven drying, sticky beans that clump on the drying bed, and increased susceptibility to mold during the drying phase.
Managing Fermentation Quality and Environmental Responsibility
Tank hygiene matters enormously for consistent fermentation outcomes. Fermentation tanks must be thoroughly cleaned between batches, because residues from previous ferments harbor microbial communities that may not match the culture balance appropriate for the new batch. An unwashed tank from a previous over-fermented lot will inoculate the next batch with a skewed microbial population and potentially produce similar off-notes even if everything else is done correctly. Cleaning is a non-negotiable operational step.
Water management is the other dimension of responsible fermentation on a small farm. Wet processing is water-intensive. The water that fills the fermentation tanks, absorbs the dissolved mucilage and microbial byproducts, and drains out at the end of fermentation carries a high biochemical oxygen demand. This wastewater, sometimes called coffee effluent or the Spanish term "pulping water," is acidic and nutrient-rich. Discharged untreated into streams, it can deplete oxygen levels and damage aquatic ecosystems.
Responsible farms, including our own operation here in Holualoa, treat this wastewater as a resource rather than waste. Combined with the pulp from the pulping step, the fermentation effluent is composted and applied to the orchard as a soil amendment. This returns organic matter and nutrients to the soil, reduces the need for synthetic fertilizers, and prevents pollution. It is the kind of Hawaiian full-circle farming practice that makes a small agricultural operation genuinely sustainable rather than simply marketing itself as such.
Step 4: Washing and Density Grading
When fermentation is confirmed complete, the beans must leave the tank and be washed as quickly as possible. Waiting in the drained or partially drained tank after fermentation is finished gives any remaining microbial activity time to continue working past the optimal point. Speed from the fermentation decision to the washing channel is important.
The Washing Channels
Washing channels are water-filled troughs through which beans flow by gravity and water movement. After fermentation, fresh clean water flushes the beans out of the tank and into the washing channel, where the dissolved mucilage, fermentation byproducts, and any remaining loose particles are carried away with the water flow. The beans are tumbled and rinsed as they move through the channel, and in many wet mill setups, multiple rinse sections ensure the beans are thoroughly clean before they emerge at the drying end.
The number of rinse passes matters. A single rinse may leave residual dissolved sugars on the parchment surface. Those residual sugars can caramelize unevenly during drying or create sticky patches that trap moisture and invite mold. Multiple passes through clean water sections ensure that by the time beans exit the washing channel, the parchment surface is genuinely clean. The water used for washing is typically fresh rather than recycled, since the washing step is specifically designed to remove what the fermentation step broke down, and dirty recycled water would simply re-deposit dissolved compounds onto the beans.
Water temperature and flow rate both influence washing effectiveness. Warm water moves dissolved compounds off the parchment more readily than cold water, which is a factor in climates where water source temperatures are very low. In Kona, groundwater temperatures are mild enough that this is rarely a limiting factor, but operators pay attention to flow volume and channel slope to ensure beans are moving steadily and being exposed to fresh water at each section of the channel.
Density Grading in the Washing Channel
One of the elegant engineering features of a well-designed washing channel is that it simultaneously cleans the beans and grades them by density. The slope of the channel and the flow rate of the water are calibrated so that denser, heavier beans move through the channel more slowly or settle toward the bottom, while lighter beans, those that are less developed or represent potential quality defects, ride higher in the water column and move faster.
This is hydraulic grading, and it works because density in a coffee seed correlates directly with quality. A denser bean has more fully developed cellular structure and a higher concentration of the sugars, starches, and aromatic precursors that become the complex flavors we love in great Kona coffee. A lighter bean, one that formed incompletely on the tree, was damaged by insects or disease, or simply never reached full maturity, has a less dense structure and fewer of those quality compounds. Water moving at a consistent speed will naturally separate them.
As beans exit the washing channel, they are diverted into quality grades based on where they settled and how they traveled through the channel. Grade 1 is the highest density designation, reserved for the heaviest, most fully developed beans. Grade 2 captures the next tier. This is why the step-by-step wet mill process functions as a layered quality-sorting system rather than a single binary pass-or-fail gate. Each stage adds a layer of refinement.
What Happens to the Different Grades
Higher-density Grade 1 beans move to premium drying lots and are typically processed, roasted, and sold as single-farm or single-variety Kona coffee, the lots that command the highest prices and carry the farm's name as a quality signal. Lower-density grades may be dried separately, sold as commodity-grade green beans, or used in blended products where the precise origin character matters less than consistent volume and pricing.
This grading distinction is part of the reason that understanding the difference between Kona coffee and a Kona blend matters to consumers. A Kona blend may legally contain as little as 10 percent Kona coffee, with the remainder being coffee from other origins. A pure 100 percent Kona lot from a farm that runs its own wet mill and grades its own beans by density is a fundamentally different product from a commodity blend, in terms of traceability, consistency, and the quality investment represented by every step described in this article.
After washing and grading, beans are still enclosed in their parchment layer. They are wet, clean, and ready for drying. The parchment stage is not complete until the beans are dried down to target moisture content, and this drying process is as nuanced and influential as any of the steps that came before it.
Step 5: Drying and Conditioning
The wet mill process does not end when the water stops. Drying is the final major phase of wet milling, and it is where the moisture content of the bean is carefully reduced from the high levels that exist after washing to the stable, storage-ready level that allows the green bean to be held, transported, and roasted without risk of mold, breakage, or quality degradation. Done well, drying is a slow, attentive process that respects the bean's structure. Done poorly or rushed, it creates internal stresses that undermine all the careful work that came before it.
Raised Bed or Patio Drying Under the Kona Sun
Freshly washed beans, still enclosed in their parchment, arrive at the drying area carrying a moisture content of somewhere between 50 and 60 percent, the natural water content of a living seed that has been saturated by washing. The target moisture for storage-ready parchment coffee is approximately 10 to 12 percent. The drying process must move the bean from one extreme to the other without rushing, without cracking the parchment, without allowing surface mold, and without creating a situation where the outer layers of the bean dry faster than the interior.
At Buddha's Cup, we dry beans on raised beds or concrete patios in the open air, spreading them in a layer thin enough to allow airflow through the bed rather than creating deep piles where interior moisture cannot escape. Raised beds are preferred for quality drying because they allow air to circulate beneath the beans as well as over them, which produces more even moisture loss. Concrete patios can heat more rapidly in direct sunlight, which speeds drying but requires more careful monitoring to prevent surface overheating.
Kona's microclimate provides a natural drying environment that is genuinely difficult to replicate artificially. Mornings are typically sunny and warm, providing the radiant energy that drives moisture evaporation. Afternoons bring the cloud cover that moderates temperature and slows the drying rate, preventing the rapid moisture loss that would stress the bean's cellular structure and cause the parchment to crack or the seed to fracture internally. This gentle, diurnal drying rhythm, sunny mornings and cloudy afternoons, is one of the factors that makes sun-drying coffee beans in Kona produce such stable, high-quality results.
Drying Time, Turning, and Monitoring
Full sun drying on a Kona farm typically requires one to two weeks, depending on weather patterns, ambient humidity, bed depth, and the density of the bean lot.