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What Is Anaerobic Processing in Coffee?

Coffee is always improving. Recently, innovative coffee producers have been experimenting with anaerobic processing, in which coffee is fermented without oxygen. This divergent process, apt to repair and test itself, results in rare and exotic flavors that don't taste the same.

Although anaerobic fermentation is relatively new, aerobic fermentation involving oxygen is a common practice. Due to the presence of water, sugar, bacteria and yeast, fermentation will begin as soon as the coffee is taken. The sugars and acids in the mucilage of coffee are then converted into different acids, CO2, ethyl alcohol and other compounds. The green coffee bean will ferment slightly differently depending on whether it is washed, natural or honey, thus resulting in a variety of flavors.

Freshly picked cherries are ready for stage 1 fermentation!

Compared to aerobic fermentation, anaerobic fermentation produces different acids, such as lactic acids, which impart a striking flavor to the final product. During this process, the anaerobics are placed in sealed tanks that are pressurized from the CO2 buildup, and the residual pressure and oxygen are then vented out using relief valves. This added pressure forces juices and sugars into green coffee beans. Fermentation can take place in cherries or can be pulped in mucilage. The coffee is then dried in cherry (natural), mucilage (honey) or washed and dried.


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