Let's start by remembering what we learned in school, Fermentation is a chemical reaction that causes a substance to break down into other, simpler substances. Which means that fermentation can enhance the flavor of a coffee or ruin it. That's why it's important to do it in a very controlled manner.
There are several types of fermentation, each of which adds different qualities to our cups. Today, we want to discover how they work and what benefits the different processes add to our coffee.
In the coffee process, fermentation is key after harvesting and can occur in different ways:
Aerobic and anaerobic fermentation
These are the most common in traditional processes. The first is "simpler"; in this, the microorganisms work alone. In the second, the coffee cherries are placed in a tank and covered with water. But the aerobic process is not as simple; it requires greater control and monitoring, as it is more variable with time and temperature. These have been the traditional processes, commonly used until recently, and basically the only goal was to break down the mucilage surrounding the bean. But researchers and producers, with the goal of always improving the cup, found in this process a way to add value to specialty coffees.
Fermentation by carbonic maceration
It is a process that seeks to obtain a more aromatic cup profile, with sweet notes and much more body. The process is as follows: the whole coffee cherry is placed in an airtight stainless steel tank, the presence of oxygen is eliminated, and the container is filled with carbon dioxide. This process can last from just a few hours to several days. Carbon dioxide prolongs fermentation by slowing the breakdown of sugars. The oxygen-free environment favors the action of microorganisms during fermentation, thus developing unusual flavors without the vinegary notes typical of long fermentation. Furthermore, the pH also evolves more slowly, resulting in lower acidity.
Fermentation with yeast
In the yeast fermentation process, coffee cherries are traditionally washed with a solution before pulping. This process is carried out until the cherry skins are shiny. Always taking into account the variables of time and the microorganisms used in the process, both of which are essential for a successful fermentation process, after the coffee is pulped, the yeast is activated in potable water, and this mixture is then taken along with the coffee to fermentation under controlled conditions. It is said that yeast has the power to change the lives of producers, making the fermentation process much easier, but also more delicate and requiring greater control.
A large part of yeast's contribution to the coffee production process is to standardize the flavors of the production, rather than marking different flavors with each harvest. This process is said to result in a clean coffee in the cup with far fewer defects. The yeast helps increase the body and sweetness of the beverage due to the polysaccharides generated during fermentation that enter the bean and remain throughout the process until the bean is roasted. Additionally, acidity increases due to the formation of organic acids that produce fruity flavors in the cup.
Freeze fermentation
Freezing began as a post-harvest preservation and processing process during times of overproduction, with the idea of ββtreating the coffee bean like a fruit and thus preserving it for much longer during processing. This process involves freezing the coffee from a temperature of approximately 35 degrees Celsius to around 4 degrees Celsius in approximately 8 hours. The beans are then frozen for between 95 and 145 hours, depending on the desired profiles. After the thawing process, a traditional fermentation process is carried out.
It has been discovered that freezing enhances the sugars and sweetness of the grains, in addition to reducing acidity. Among the flavor notes attributed to the freezing process, the most notable is lychee, accompanied by flavors of various tropical fruits, which are not evident in the cup with the traditional process. This process also adds new fragrances and aromas to the cup, in addition to giving it a creamy and silky body. Its flavor is very clean since cold processing attenuates the coffee's intensity.
Alcoholic fermentation
Regardless of the type of fermentation used in our coffee, we should understand the processes and the benefits they bring to our cup. Knowing these benefits encourages us to take the time and focus to discover everything that stands out when we drink good coffee.