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What is anaerobic fermentation?
Did you know that in the world of coffee, the flavor can vary greatly not only depending on the growing region and variety, but also on the post-harvest processing method?
Among these, a method called "Anaerobic Fermentation" has been gaining attention in recent years.
This processing method, which involves fermentation in an oxygen-deprived environment, creates unique aromas and complex flavors through a process that differs from traditional methods.
In this article, we will delve into the mechanism of this new processing method, its differences from others, its flavor characteristics, and even recommended ways to enjoy it.
What is a processing method? A crucial step that affects coffee quality
When coffee beans are harvested, they are in the form of fruit (coffee cherries). The process of extracting the seeds from the fruit, drying them, and preparing them for roasting is called "processing method."
Common processing methods include the following:
- Natural: The entire fruit is sun-dried, and the pulp is removed after drying. Characterized by a fruity and sweet flavor.
- Washed: The pulp is removed, and the beans are fermented and washed with water before drying. Characterized by a clean and refreshing acidity.
- Honey: After removing the pulp, some mucilage is left on the bean to dry. Offers a balanced sweetness and acidity.
In addition to these, "Anaerobic Fermentation" has been gaining popularity in recent years. A major characteristic is that fermentation is carried out in a more controlled environment compared to traditional methods.
Mechanism of Anaerobic Fermentation
"Anaerobic" refers to an environment without oxygen.
In normal washed processing, coffee cherries from which the pulp has been removed are placed in tanks and fermented in the presence of oxygen. In contrast, in anaerobic fermentation, the fruit or seeds are fermented in sealed tanks in an oxygen-deprived state.
In this environment, different microorganisms than usual are at work, and unique chemical changes occur. As a result, flavors that are difficult to produce with general processing methods are brought out.
How fermentation is carried out
- Harvested coffee cherries are put into a tank.
- Oxygen is cut off (a mechanism that allows carbon dioxide to escape through a valve but prevents oxygen from entering).
- Fermentation is managed for several tens of hours to several days.
- After fermentation, the process moves to drying.
Thus, it can be said that this processing method requires meticulous temperature control and time adjustment, and the experience and skill of the producer greatly influence it.
Differences from other processing methods
Compared to traditional natural and washed methods, anaerobic fermentation has the following differences:
- Differences in fermentation environment: Because it is carried out in the absence of oxygen, the types of bacteria at work and the chemical reactions change.
- Uniqueness of flavor: More complex and unique flavors are emphasized.
- Difficulty of management: Requires tanks and valves, and the quality can vary greatly depending on the adjustment of fermentation time.
Although it requires more effort and cost than conventional methods, its appeal lies in its ability to express a uniqueness not found in other processing methods.
Flavor characteristics of anaerobic fermentation
Coffee processed with this method often exhibits the following characteristics:
- Aroma of tropical fruits
- Rich flavor reminiscent of wine or rum
- Lingering finish with a complex interplay of acidity, sweetness, and bitterness
Because it offers a multi-layered taste in a single cup, there is the "joy of tracing changes in aroma" during tasting.
Compared to traditional washed or natural methods, it often results in a more impactful flavor.
Reasons why Anaerobic Fermentation is attracting attention
The reasons why anaerobic fermentation is attracting attention worldwide include the following:
- Expansion of the specialty coffee market: Increasing demand for new flavors has led more farms to adopt this method for differentiation.
- Recognition in coffee competitions: Beans processed with this method have received high evaluations in barista world championships and other competitions, raising its profile.
- High experiential value: Because it offers new discoveries with every sip, it is highly popular among coffee lovers as a "special cup."
Recommended ways to enjoy
Coffee processed with anaerobic fermentation offers unique flavors, so the following brewing methods are recommended:
- Hand drip: Allows for easy adjustment of brewing conditions and a leisurely enjoyment of changes in aroma and taste.
- French press: Brings out the oiliness and richness, allowing you to directly experience the complex flavors.
- Iced coffee: Allows for a refreshing enjoyment of tropical aromas and the sweet-sour notes derived from fermentation.
However, as the individuality is strong, it's a good idea to start with a small amount and find the brewing method you prefer.
Summary
Anaerobic fermentation is an innovative processing method that involves fermentation in an oxygen-deprived environment.
It produces unique flavors not found in traditional natural or washed methods, offering aromas reminiscent of tropical fruits and wine.
Its distinctive taste will allow you to rediscover the depth of coffee. As a cup that further expands the world of specialty coffee, please give it a try.
