Processing Methods

Processing methods are at the core of our interest of what coffee can be. Coffee processing is arguably the most important stage responsible for a coffee's flavor. There are many philosophies and opinions about what correct processing is, so we obviously have a few opinions ourselves, and you can taste it more than anything. From the purist outlook, seeing the fullest expression of the coffees terroir and how a cultivar is influenced by its surroundings shows the true transparency of all the nutrients and minerals and best practices. Humans can only interfere with the coffees quality with this mind-frame, and even though the best way to show the coffees purity of flavor is by forcibly removing any aspect of fruit and mucilage as to isolate the seed for further drying, grading, shipping and roasting. This purist approach is where wet process (or washed process) is most preferred for it's ability to focus purely on the inherent qualities of what it is, and where it comes from.

On the other end of the scale, we have our appreciation of experimental ideas, innovation, and a lust for discovery. New flavors can emerge, not inherent to the land, but of the process it self. Some have rejected dry processed (or Natural process) as fitting within a purist's scope because the process used to be prone to over fermentation and negative flavors, but this was the standard in Yemen and Ethiopia for hundreds of years before washing became a necessity of the americas, and even wet hulling in the Indo-Pacific because of the heightened humidity which would cause molding and more fermentation issues. Access to technology, equipment, and knowledge (thanks to the rapid spread of phones and social forums). Many of us like milk, but cheese is a whole new world of flavor thanks to to microorganisms who have their own story to share. Beers can be malty, hoppy, crisp and clearly showcasing those ingredients like in german lagers, or it can be a funky Belgian which is almost entirely fruity esters from the yeasts or even a spontaneous wild ferment in an open vat fermenter.

We try to run the gamut in every scope and scale of coffee processing to showcase what we love and what we represent. the marriage of tradition and innovation, the valley of heart's delight, and silicon valley. Coffee drinking is changing, and we're right there, not just on the beat, but trying to pave the path moving forward with our own contributions to the industry, weather it be cthe coffee itself with our hards on, boots on the ground approach with producers on the fields and mills, or back home thinking of new ways to serve our favorite product and creating future focused equipment and machinery.

With that, we will review some terminology and list the processing methods (because of the recent innovations in processing, we're also going to categorize the processes, and provide some alternative names) We'll also break down the parts of the coffee fruit.

Get ready, it's biology class:

From the inside out:

Coffee Seed: (endosperm) a raw “coffee bean” made of insoluble & soluble components, further processing required before consumption. We prefer roasting them deliberately. This is that golden bit, not a bean at all, just a seed, beaming with potential.

Silver skin: (spermoderm) thin layer in direct contact with the coffee seed becomes chaff, a byproduct of the coffee roasting process.

Parchment: (endocarp) all coffees are dried in their parchment in some form (except wet hulling) before it is removed during milling/dry hulling.

Palisades Cells: (parenchyma) thin layer of mucilaginous tissue typically consumed by naturally occuring enzymes during fermentation.

Mucilage, Pulp: (mesocarp) oozing with sugars this layer is removed via fermentation during wet processing or left to dry on the parchment for a couple weeks before hulling.

Outer Skin: (epicarp) typically removed with a de-pulper before wet & honey process, and left intact in dry and other natural processes. Can vary greatly in color.

The Traditional Methods:

DRY PROCESS: The simplest, most straightforward, conceptually, but can also be the hardest for some to execute. Often, the term dry process can be used interchangeably with "natural" process.

After harvesting the ripe fruit, the fruit is laid out to dry on concrete patios, like they do in Brazil, or on rooftops, like in Yemen, or they could be laid out on raised beds like they do in Ethiopia. Alternatively, they can also be mechanically dried in big rotating ovens. We often don't opt for the mechanically dried as it can lower cup score, yet it can be more efficient, specially if there is a shortage of patio space.

WET PROCESS: This is also known as "washed" process, and uses lots of water. We have typically avoided the term washed because it could imply other processes can be "dirty" when that simply isn't the case, and it's more about "washing" all the fruit stuff away.

After harvesting the ripe fruit, the fruit is rinsed off of any debris and soil from the trees and the field. it is then moved to a piece of machinery called a de-pulper (or confusingly enough; a pulper) to have the skin removed. That skin can then be dried into cascara. As for the slimy coffee fruit this is where it can go to be either honey or continue onto being washed. after de-pulping, the slimy beans are still covered in a very fibrous mucilage that is very challenging to mechanically remove (but not impossible), so typically leaving them to "ferment" in a large tank (typically a concrete silo, preferably tiled for cleanliness) for 12-72. The duration depends on environmental factors and temperatures. typically the coffee is not submerged under water, and can develop lots of heat from multiple chemical and enzymatic reactions. The idea is to only breakdown the mucilage enough so that parchment bean can later be moved through canals with water to knock off whatever remainder mucilage there is to then move the washed parchment to drying patios, raised beds, or even mechanical dryers (none of the coffees we purchase are mechanically dried, we strongly feel that heat at this stage of the process lowers cup quality).

HONEY PROCESS: also sometimes called pulped natural (in Brazil, because there isn't the ferment or washing aspect). It is also sometimes referred to as "semi-washed", but in an attempt to avoid ambiguity, we avoid the term as it can also be synonymous to "wet hulled" which is totally different, and provides a very different cup profile.

Honey processing in it's simplest understanding starts off just like wet processed lots; after harvest, the fruit is rinsed off of any debris and soil from the trees and the field. it is then moved to a piece of machinery called a de-pulper (or confusingly enough; a pulper) to have the skin removed. That skin can then be dried into cascara. This is where the differences between wet and honey begin. Instead of removing the mucilage, the coffee is laid out to dry. Different quantities of mucilage can be left on the beans, and different degrees of oxidation can be allowed to create different styles of honey processing:

White Honey: Minimal mucilage left, yielding clean and subtle flavors.
Yellow Honey: Slightly more mucilage, with balanced acidity and sweetness.
Red Honey: A thicker layer of mucilage leads to fruitier and more pronounced flavors.
Purple Honey: Extended oxidation introduces deeper, complex flavor profiles.
Black Honey: The most mucilage and longest drying time create bold, wine-like intensity.

Honey Processing in this day and age can also refer to it's physical state within an experimental process, such as double anaerobics, where one stage of processing might be done as a natural, de-pulped, and fermented a second time as a honey, and dried as such as well.

Other Classic Methods of note:

Wet Hulling (Giling Basah): Common in Indonesia, this method removes parchment while the bean is still wet, creating earthy, full-bodied profiles.

Double Washed (Kenya Style): Features an extra fermentation and rinse stage for exceptionally clean, vibrant coffees.

Innovation in Coffee Processing: A Flavor Revolution

If you thought coffee processing was just about drying beans on a patio, buckle up. These new methods are redefining what coffee can taste like. Producers are turning to science and creativity to push boundaries, crafting coffees that blow our minds (and palates). Think of it like a new wave of craft brewing or wine-making, where every step has a purpose and every experiment tells a story.

Mossto: Reclaimed Processing

A natural fermentation method that uses the juice from previously fermented cherries to enrich the next batch. Known as film yeast fermentation, it creates coffees that are deeply complex and flavorful.

Double Anaerobic Fermentation: Two Times the Magic

This one's for the fermentation nerds. In Double Anaerobic Fermentation, coffee cherries start by fermenting in an oxygen-free tank. This stage enhances fruity, lactic notes (think yogurt meets tropical fruit). Then, the cherries are pulped, and the mucilage-covered beans go back into another anaerobic environment for a second round. Each stage is carefully timed and monitored to avoid sour flavors while amplifying sweetness and complexity. The result? A cup that’s bold, layered, and smooth—like a well-told story.

Thermal Shock: Science Meets Drama

Ever tried flash-freezing your coffee? Okay, maybe not, but Thermal Shock isn’t far off. It’s all about alternating between hot and cold water during fermentation. Why? The sudden temperature changes stress the coffee at a cellular level, releasing sugars and aromatics you didn’t even know were there. It’s like hitting "shuffle" on your coffee’s flavor playlist: bright, sweet, and unexpectedly smooth.

Thermal Stroke: Coffee's Slow Burn

Thermal Stroke takes the temperature game further by extending it over the drying phase. Think hot and cold cycling, but drawn out over days or even weeks. This extended exposure allows deeper caramelization of sugars and more nuanced flavor development. The result? A coffee with drama, elegance, and the kind of complexity that keeps you coming back for another sip.

Co-Fermentation: Coffee’s Wild Side

What happens when coffee parties with passionfruit, cinnamon, or even pineapple? Co-Fermentation, that’s what. Producers add fruits, spices, or herbs to the mix during fermentation, allowing the coffee to absorb their flavors. The science? These additives bring in their own unique microbial ecosystems, creating a sensory crossover event. Think tropical vibes, floral explosions, or even warm, spicy undertones. It’s coffee reinvented, one experiment at a time.

Koji Processing: Sake, Meet Coffee

This one’s for the culinary crossover fans. Koji Processing borrows its magic from sake brewing. Koji mold (yep, mold) breaks down coffee mucilage with enzymes, unlocking natural sugars and creating savory-sweet umami notes. The result? Coffees that feel like they’ve been aged in the finest barrels, full of intrigue and surprising sweetness.

Hybrid Processes: The Best of Everything

Coffee processing is no longer about sticking to one script. Hybrids mix methods to create something entirely new:

Supernatural: Start with anaerobic fermentation, then dry the cherries like a natural process. The result? Bold fruity notes with a cleaner finish.

Hydro-Honey: A honey process with extra rinsing stages. It balances the clarity of a washed coffee with the sweetness of honey.

Controlled Carbonic Maceration: A mic-drop hybrid that uses precise pH and CO2 controls to finesse every flavor note.

Why These Methods Matter

These innovative methods represent the coffee industry's shift towards a more scientific, precise approach, expanding the boundaries of what coffee can be. Each technique requires a mix of experimentation and understanding of biochemistry, making them accessible primarily to producers with the resources and willingness to take risks.