What do we mean when we talk about anaerobic fermentation?

As specialty coffee has been gaining popularity, producers have generated new ways of processing their coffees in order to offer different cups or specific profiles, either to differentiate themselves from the rest, out of a deep passion for coffee, or to make the most of their harvests and resources. It is becoming more and more common to find coffees where emphasis is placed on the type of process that they have received, the type of fermentation, the fermentation time, the temperature, etc. Some years ago we began to find coffees that included anaerobic fermentation in their description.

It is very likely that at some time when buying specialty coffee you have come across a process described with these words, but...

 What is an anaerobic fermentation?

Before continuing to talk about anaerobic fermentations, it would be interesting to go one step further and ask ourselves, what is a fermentation? 

According to Wikipedia fermentation is a catabolic catabolic process of oxidation incomplete oxidation, which does not require oxygen, and whose final product is an organic compound. That is, through fermentation, some organisms, such as yeasts and bacteria, obtain energy by degrading organic molecules, such as starch or sugar, resulting in a simpler organic compound. A simple example of this would be alcoholic fermentation, in which certain microorganisms transform grape sugars into ethyl alcohol and CO2, resulting in wine. Or the production of yogurt by fermenting milk with lactic ferments. Fermentation itself is an anaerobic process, as it does not require oxygen to occur.

In spite of the fact that when we talk about the fermentation of coffee, we always believe that its purpose is to obtain a specific profile in the cup -and in this post we talk precisely about this-, fermentation is also the oldest way of separating the cherry from the coffee beans. The coffee was left to ferment passively, that is to say, without generating any type of control over that fermentation, until the skin and mucilage separated from the bean, making it easier to obtain the coffee beans. Today this process is still used in those places that do not have a mechanical pulper. This means that practically all coffees go through a fermentation process, from natural coffees and honeys to washed coffees that have not been mechanically pulped. 

So, if fermentation is already an anaerobic process in itself, why do we talk about anaerobic fermentation to describe some coffees? In this case, the term anaerobic refers to the environment in which it occurs. When we speak of coffees with anaerobic fermentation we refer to the environment without oxygen: sealed tanks with a one-way valve to allow the gases to exit, but not to allow them to enter. The presence or lack of oxygen changes the type of microorganisms that we find in it. Therefore, we can find washed coffees, honeys or natural coffees that also include anaerobic fermentation in the way they have been processed.

Nomad has as one of its main objectives to offer a varied and dynamic menu, with a wide range of origins and processes, respecting seasonality, and discovering new and different profiles: from the most classic ones with notes of chocolate and nuts, soft and honeyed acidities to more enzymatic coffees, with bright acidities and tropical or floral notes. 

This year we are once again incorporating into our menu the process pack from the Aquiares farm in Costa Rica. It consists of the same coffee variety: Central American, a hybrid cross between Rume Sudan from Ethiopia, delicate and complex, and Sarchimor from Central America, with vigorous production and large beans. Diego Robelo and his team have carried out four different processes: a first batch Washed, a second batch Washed with a 96 hour fermentation under anaerobic conditions to which a mixture of water and molasses is added, a third batch with a red honey process and a fourth batch with a natural process, fermented under anaerobic conditions with the incorporation of a must from previous fermentations. Tasting the coffees in our HQ we have been able to see the differences that each batch offered us. If you would like to know a little more about the coffees that make up this pack and have the chance to try them at home, you can find them in our online store or in our stores. We think it is a fun way to see how the processes applied to the coffee once it has been harvested can help to offer multiple varieties of profile and cup.

If you want to learn more about coffee, we recommend the podcasts of "Making Coffee with Lucia Solis". Lucia Solis, who in addition to working with producers as a consultant and designing fermentations for their farms, has created a series of podcasts where she talks about different processes from a technical point of view and shares her experiences and opinions on topics related to coffee.