anaeróbna fermentácia

The field of coffee processing is constantly evolving. Recently, innovative coffee producers have been experimenting with anaerobic processing, in which coffee is fermented without oxygen. This distinct process results in rare and exotic flavors. Although anaerobic fermentation is relatively new, aerobic fermentation—where oxygen is involved in the process—is common practice. This is standard practice for traditionally processed coffees. Fermentation begins immediately after harvesting the coffee due to the presence of water, sugar, bacteria, and yeasts. The sugars and acids in the coffee pulp then transform into various acids, CO2, ethyl alcohol, and other compounds. Coffee always ferments slightly differently depending on whether it undergoes a washed, natural, or semi-washed process, leading to various flavor variations. Anaerobic fermentation This is a method of fermenting coffee in a sealed tank with a one-way valve, which serves to stop the supply of oxygen into the container. For better results, the temperature of the tank is also regulated. Unlike the types of fermentation used in traditional coffee processing methods, this is a controlled and purposefully extended fermentation. This process can be carried out in specialized tanks, barrels, or even in plastic GrainPro bags. The key is that the coffee is sealed without air access for a certain period. This can be done either before the cherries are depulped or afterward. In both cases, microorganisms begin to break down glucose molecules—a chemical reaction that generates CO2 and heat. This causes oxygen to be pushed out of the tank through the one-way valve. Bacteria naturally present in the coffee cherry produce enzymes during this process, leading to the formation of simpler compounds such as organic acids and alcohols. “Fermentation tanks with a one-way valve” How does anaerobic fermentation affect the final taste of coffee? Controlling and extending coffee fermentation leads to a change in its chemical composition, and thus in its organoleptic profile. Fermentation can enhance flavor or create different flavor profiles from the very same coffee. For example, coffee with a 48-hour fermentation process will not taste the same as coffee with a 100-hour fermentation. Dr. Britta Folmer states in The Craft and Science of Coffee that "depulping through underwater fermentation reportedly increases acidity and aroma while moderating astringency." On the other hand, an excessively long fermentation can have the opposite effect: acidity, body, and aroma are lost. Coffee producers strive to find a balance where flavor and aroma are highlighted without losing the key characteristics of the coffee. Carbonic maceration The only difference between anaerobic fermentation and carbonic maceration is that in carbonic maceration, carbon dioxide is injected into the fermentation tank after the coffee cherries are placed inside and the vessel is sealed. This displaces all oxygen. Just as in anaerobic fermentation, it is crucial to control temperature, pH, and sugar levels. How does carbonic maceration affect coffee and why is it used? The reason for using carbonic maceration instead of anaerobic fermentation is that injecting carbon dioxide into the tank and removing all oxygen slows down the fermentation process. Because no oxygen is present (thus no oxidation occurs), the breakdown of glucose is slower, as is the pH development. It also makes it easier to control various parameters to achieve different results. Sasa Sestic, World Barista Champion and a pioneer in applying this process, claims that by regulating temperature, you can control both acidity and sweetness. At low temperatures, acidity increases, whereas at high temperatures, sweetness increases. Just as with anaerobic fermentation, the goal is to enhance the coffee's qualities by boosting aroma, improving sweetness and acidity, and obtaining coffee with a richer flavor structure. Lactic fermentation Anaerobic coffee fermentation and carbonic maceration are the two most common processes currently used to enhance the organoleptic properties of coffee, but they are not the only ones. To achieve these results, other processes exist, some in more experimental stages than others. These include lactic fermentation, fermentation with kombucha cultures, wine yeasts, or water kefir. Coffee contains various bacteria that drive the fermentation process, among which are lactic acid bacteria. These are the same bacteria responsible for fermentation processes in dairy products as well as fermented vegetables. In the process of lactic coffee fermentation, conditions are managed by regulating oxygen, for example through the proliferation of these bacteria and others (such as aerobic bacteria). This alters the fermentation process, making it possible to achieve diverse results. Some producers also experiment with other processes, attempting to introduce bacteria responsible for fermentation in kombucha cultures and kefir into the coffee fermentation process. One way to achieve this is to let the coffee cherries ferment in a kombucha or water kefir solution. Coffee freezing – freeze-drying (lyophilization) Another experimental method of coffee processing is freezing. Lyophilization is a process commonly used in food processing. Its goal is to remove water from products and extend their shelf life. The process consists of various steps. First, the temperature of the coffee is lowered, usually to around -40 °C, causing the water present in the coffee to freeze. Later, the pressure in the freezing chamber is reduced, leading to sublimation of the frozen water. Finally, the moisture is removed from the coffee. Typically, the temperature of the coffee is raised in the drying chamber while reducing the pressure, thereby reaching the target level of residual moisture. The purpose of these coffee processing experiments is to expand knowledge about flavors, acidity, sweetness, and cup body, and to increase the potential of the product that farmers sell. We at Goriffee are always thrilled whenever we can test new experiments, as they often bring fresh, exciting flavors and unique combinations.