What Is Anaerobic Fermentation?

Borrowing From The Wine Industry 

What makes one coffee bright and fruity while another tastes more chocolaty or nutty? Growing conditions, coffee variety, and roasting all play a role, but another important factor is how the coffee is processed.

In our recent blog post, we explored the three most common processing methods—natural, washed, and honey—and how each influences flavor. If you missed it, you can read it here. This time, we're taking a closer look at one of the most intriguing methods coffee farmers are exploring today: anaerobic fermentation.

Borrowed from the wine industry, anaerobic fermentation is a relatively recent innovation in coffee processing. In 2015, specialty coffee pioneer Saša Šestić brought the technique into the spotlight when he won the World Barista Championship using anaerobically fermented coffee, opening the door to new possibilities for coffee growers. Since then, anaerobic processing has inspired a wave of experimentation, producing some of the most unique and wildly flavorful coffees on the market.

What Is Anaerobic Coffee Processing?

Coffee processing begins after the cherries are picked from the tree. Before the beans can be roasted, they must be separated from the surrounding fruit and dried to a stable moisture level. How producers approach these steps can have a meaningful influence on the final flavor.

Anaerobic fermentation is a method in which coffee cherries, or de-pulped coffee beans, ferment in a sealed environment with limited oxygen. During this time, naturally occurring microorganisms break down sugars and other compounds, creating changes that can influence the coffee’s aroma and taste.

Producers carefully monitor factors such as temperature, time, and the condition of the coffee throughout the process. These variables can affect how the coffee develops, giving producers opportunities to explore distinctive flavor profiles while maintaining control over quality.

Anaerobic fermentation generally results in pronounced fruit notes, complex aromatics, and layers of sweetness. Some coffees may burst with tropical fruits while others develop unusual flavor combinations.There is no single flavor that defines an anaerobic coffee. Each harvest responds differently to its environment and processing conditions, which is part of what makes exploring these coffees so fun. 

Combining Methods— Edwin Zambrano's Approach 

One of the most exciting things happening on coffee farms today is the experimentation with combining processing methods. A great example is our Colombian coffee grown by Edwin Zambrano. By combining natural and anaerobic processing, Edwin creates a beautifully layered, complex coffee bursting with fruit-forward flavors.

As you may remember, natural processing involves drying coffee cherries with the fruit intact, allowing the fruit to influence the coffee's flavor. Edwin takes this a step further by introducing anaerobic fermentation in oxygen-free tanks, further enhancing those fruity characteristics. Both methods require patience, precision, and careful monitoring. By combining these techniques, Edwin brings out the very best in his coffee, creating something truly unique.

 Meet Edwin Zambrano

When we first began sourcing this coffee, the farm was run by Edwin’s mother, Doña Nohora. Several years ago, Edwin and his wife took over the family farm, carrying forward his mother’s lifelong commitment to quality while bringing their own approach to coffee production.

Each year, Edwin selects the finest cherries from his harvest to create this special micro-lot. He begins by fermenting the cherries in oxygen-free tanks for more than 60 hours, then carefully spreads them across raised beds to dry in the sun for 45 days. The result is a beautifully complex coffee bursting with notes of juicy orange, sweet pineapple, fresh strawberry, and dark chocolate.

Edwin’s dedication has made this one of our customers’ favorite coffees and earned it recognition as a prestigious Good Food Award winner.

Discover the Difference for Yourself

The best way to appreciate the impact of coffee processing is to taste it for yourself! With vibrant notes of juicy orange, sweet pineapple, fresh strawberry, and dark chocolate, Edwin Zambrano's Colombian coffee is a delicious example of what careful processing and craftsmanship can achieve. We invite you to give it a try and discover what makes this coffee so special.