Aerobic Fermentation and Anaerobic FermentationAerobic fermentation and anaerobic fermentation are the two primary types of fermentation. The term "aerobic" is derived from the Ancient Greek words "aér" (air) and "bios" (life), indicating that new life arises based on the presence or absence of air. When it comes to coffee, this distinction is particularly relevant. Aerobic fermentation, involving the presence of air, is more intricate and challenging to control. On the other hand, anaerobic fermentation, which occurs in the absence of air, is more manageable due to the absence of the oxygen variable. While it might seem that anaerobic fermentation is the preferable choice, both methods have their unique advantages.
So, what sets aerobic and anaerobic fermentation apart? Aerobic fermentation allows the coffee to undergo the process with minimal interference, monitoring only time and temperature. Freshly harvested cherries are collected and immersed in water in an open-air tank, breaking down rapidly over 16 to 20 hours. Since the coffee is exposed to various elements, close monitoring is crucial. Airborne microbes and yeasts are attracted to the sugar-rich cherries and, without proper attention, can proliferate uncontrollably, leading to undesirable flavors reminiscent of vinegar.
In contrast, anaerobic fermentation follows the same initial process, but the fermentation tanks are tightly sealed to prevent the entry of oxygen. Nitrogen and carbon dioxide are the main gases present during anaerobic fermentation, and they are vented as needed. In these conditions, coffee cherries undergo glycolysis, a metabolic process that synthesizes energy from glucose. This energy aids in breaking down the mucilage over a period of up to four days, compared to the under-one-day breakdown in aerobic fermentation. The extended breakdown time is not only easier to manage but also imparts distinctive flavors and lactic acids to the coffee.
Specialty coffee comes in various forms, and aerobic- and anaerobic-fermented coffees contribute to propelling our centuries-old industry into the future. This continual innovation is what makes working with, drinking, and exploring coffee so enjoyable. Producers and roasters consistently find ways to revolutionize a simple seed, making each iteration feel brand-new. While there's an appreciation for classic coffee, the excitement lies in tasting something that seems extraordinary. In our busy lives, there's often little time to pause and observe, but specialty coffee provides that opportunity. Crafting a delicious cup takes effort, and within that time, there's a chance to observe, learn, and rediscover the love for coffee all over again.