When someone mentions fermentation, coffee usually isn’t the first thing to come to mind.
Maybe you picture a dark wine cellar, barrels propped up in rows, the wine quietly aging in the cool damp darkness. Or maybe you think of your favorite brewery down the road, that one funky
IPA you can't wait to try, all those stainless steel tanks turning grain, hops, yeast, and water into something entirely new and incredibly old.
Or maybe you think of the sourdough starter in the fridge, bubbling as if it were a sentient creature.
Fermentation is all around us and comes in hundreds of forms. We have been fermenting things for thousands of years and will continue for another.
So what happens when we invite all those microorganisms to coffee?
If you have? spent any time in specialty coffee spaces, you have probably noticed the word “anaerobic” thrown around. Maybe on a label of a single origin coffee, or on the menu as an espresso offering. Maybe you’ve grown familiar with anticipating anaerobic coffee’s flavor to be described by terms that would be more at home on a wine list (think fruit, spices, or citrus forward).
Whether you are already familiar or if this is the first time you're hearing about it, chances are you understand more than you think!
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At its most basic, fermentation is a biological process in which microorganisms, mostly yeast and bacteria, transform sugars into other compounds. In wine, the yeast would consume the sugars from the grapes and produce not only the alcohol but carbon dioxide and the various other compounds that add to the character and flavor of the finished wine.
And that’s also true with coffee.
The coffee cherry contains all the basic ingredients for this process to occur. Sugars, acids, moisture, all support the necessary microbial activity for fermentation. Once coffee is harvested, naturally occurring microorganisms begin interacting with the fruit. Producers can influence that process through variables like temperature, time, oxygen availability, and how the coffee is dried.
For a deeper look at the skill of manipulating fermentation for food and drink the Brewers Association’s fermentation resources offer a useful look at how brewers manage these variables and more.
What Does “Anaerobic” Mean?
The word anaerobic means “living without oxygen”.
An anaerobic process for coffee consists of taking the coffee cherries and placing them into a controlled environment where oxygen is limited or cut off. Putting them into these sealed ranks or drums, allows for the fermentation process to take place.
The key distinction to make is that anaerobic does not describe a specific kind of flavor but more so the process of fermentation. An anaerobic coffee isn’t necessarily going to taste boozy, funky, or intensely fruity, but rather those characteristics can happen as a result of fermentation. Most important to note: those flavors aren’t in the definition of the process.
So many factors go into the cultivate flavor: the terroir, coffee varietal, and processing all contribute to the final flavor, not just the fermentation process. Winemakers, brewers and the entirety of the coffee supply chain all have countless decisions available to them to influence what eventually ends up in your glass, mug, and cup.
So, What is “Good” Fermented Coffee?
The answer isn’t as straightforward as some might think.
There is no universal flavor or identifier that tells us that fermentation is “successful” or “good”. Similarly with beer or wine, fermentation doesn’t equal fermented flavor. It simply is a tool that can be used to extract, or rather grow a specific quality and profile.
Like with any other process in coffee, this philosophy applies. At Tenfold Coffee Company, we're interested in coffee processes that contribute something meaningful to the end cup without overwhelming what makes the coffee itself naturally special. Does the fermentation of this coffee compliment the coffee's inherent character or does it add a fun or funky complexity to the cup?
A good process gives us another way into the coffee. It creates curiosity about what we are tasting and how those flavors got there. Like a piece of music or writing, the best coffees can reveal more the longer you spend with them. You might notice the fruit first, then the acidity underneath it, then something floral or wine-like that changes as the cup cools. None of those things exist in isolation but are one piece of a larger whole.
A fermentation process like the anaerobic process opens up so many opportunities to expand the profile of the roasted coffee in so many exciting ways and directions.That is particularly apparent in the work being done by our partners at Zukuka Bora in Uganda.
Welcome Elgon Anaerobic to the Family
Our latest coffee from Uganda is the Elgon Anaerobic. Around Tenfold, we’ve started calling it simply Elgon.
It is our eighth country of origin and comes to us from Bulaago on Mt. Elgon, Uganda, through our importing partner Zukuka Bora Coffee.
Uganda has been a country of interest for Tenfold for a long time. Since Jacob, our company founder, began working in coffee, he has repeatedly heard about the potential of Ugandan coffee. It is a country with enormous agricultural potential, but one where specialty coffee infrastructure and resources haven’t always matched that potential.
That’s part of what makes working with Zukuka Bora so exciting. Their coffees have consistently been dynamic and fun, and Elgon is a particularly good example.
Elgon’s Process
Elgon is a relatively straightforward anaerobic natural process.
After the coffee is harvested, the cherries are placed in sealed drums which seals out most if not all of the oxygen. Zukuka Bora ferments the cherries for around 72 hours. Zukuka Bora has been producing anaerobic coffees for several seasons, refining the process each year based on weather, source location, farmers, and the coffee itself.
After fermentation, the coffee is moved onto raised drying racks for the first one to two days before being moved into a protected drying shelter, where it can dry slowly away from rain with the goal being to carry the flavors developed during fermentation into a stable, clean coffee rather than allowing fermentation to continue unchecked.
That is what drew us to Elgon. Not simply because it is an anaerobic coffee, but because it is an example of a producer taking a process, paying close attention to it, learning from each harvest, and using it to make something better.
That’s the part of fermentation we’re excited about at Tenfold.
SHOP ELGON ANAEROBIC HERE.