Introduction:Anaerobic fermented coffee beans often suffer from fast drawdown and thin flavor profiles, which are actually related to changes in cellular structure. This article delves into the effects of anaerobic processing on coffee beans, using practical measurements of grind particle distribution and brewing data to provide specific adjustments for grind settings and pouring techniques. These insights will help you brew richly layered and aromatic anaerobic coffee at home.
Many coffee enthusiasts encounter a frustrating issue when pour-over brewing anaerobically processed beans: even when using a grind size suitable for medium roasts, the water flows through too quickly, resulting in under-extraction and a flat, uninspired flavor. The root cause of this issue is closely tied to the profound alterations in the cellular structure of the beans caused by anaerobic fermentation.
Anaerobic processing is a method where coffee cherries are fermented in a sealed, low-temperature (around 10–15°C), oxygen-deprived environment. This process extends fermentation time, allowing the flesh and mucilage to break down more slowly. It not only enhances the coffee’s sweetness but also modifies the physical properties of the beans. Compared to traditional processing methods, anaerobically processed beans have more porous cell walls and a looser internal structure after roasting. These factors directly affect the density of the ground particles and the efficiency of extraction.
If you notice that the water drains unusually fast during pour-over, the first thing to check is your grind size. Taking commonly medium-roasted coffee beans as an example, it is generally recommended to use grind setting #10 on the EK43S grinder, which yields a particle distribution sieve retention of about 80% on a Chinese standard No. 20 sieve. However, with anaerobic beans, even using the same setting often results in a lower actual sieve retention. Test data shows that Costa Rica’s Musician Series Anaerobic Honey Mozart beans have a sieve retention of just 76% at EK43S #10, while Colombia’s Granja La Esperanza Double Anaerobic Washed Rose Valley beans register 77%.
Brewing with these grind settings, the Mozart beans had a total extraction time of about 1 minute and 47 seconds, yielding flavors of raisin, mild fermentation notes, and pineapple acidity and sweetness—but with a lack of lingering finish and an overall thin mouthfeel. The Rose Valley beans took 1 minute and 45 seconds, presenting rose and berry acidity and sweetness—but similarly lacked complexity and body. This indicates that although the sieve retention was close to ideal, the inherently loose structure of the beans still allowed water to pass too quickly, leading to insufficient extraction of flavor compounds.
To improve this situation, it is recommended to fine-tune the grind to EK43S #9.5. After adjustment, the sieve retention for Mozart beans increased to 81%, and for Rose Valley beans, it reached 82%. Brew tests showed that the Mozart beans extended their extraction time to 1 minute and 57 seconds, revealing a significantly richer flavor profile, including dried fruit-like fermentation notes, orange blossom aroma, berry acidity and sweetness, and a smooth texture with clear pineapple aftertaste. The Rose Valley beans extracted in 1 minute and 55 seconds, showcasing rose and peach blossom aromas, berry acidity and sweetness, along with a rich, winey chocolate-like finish—delivering a much more full-bodied cup overall.
If the drawdown remains too fast even after adjusting the grind, it’s time to examine your pouring technique. Regardless of the type of filter used, aim to maintain a pouring speed of about 4 grams per second, keeping the water flow steady and pouring vertically into the coffee bed. A stable pour not only promotes even extraction but also effectively prolongs contact time between water and coffee grounds, thereby improving overall extraction efficiency and flavor expression.
In summary, when facing the challenge of fast drawdown with anaerobic beans, the key lies in understanding the changes in their cellular structure and making corresponding adjustments to grind size and pouring technique. By precisely controlling grind settings and pouring speed, you can easily replicate a professional-grade anaerobic coffee experience at home and enjoy its unique aromas and rich complexity.
The above content is compiled by CoffeeHunters, a coffee news website.
