Unlocking the Secrets of Fermented Coffee

fermented coffee cherries

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Unlocking the Secrets of Fermented Coffee

Fermented Coffee can mean two entirely different things – don’t get confused 

Fermented coffee is trending. You may have heard about fermented coffee, but are you aware that two totally different concepts are connected with this?

  1. Green coffee beans that are fermented during post-harvest processing.
  2. Brewed coffee that is fermented into a drink similar to kombucha.

In this post, I will talk only about fermented green coffee beans. I am not yet ready to deal with coffee kombucha yet. Here, you will find what you need to know about fermented coffee.

As a coffee enthusiast, you know that fermented coffee is gaining popularity among coffee lovers for its unique flavor profile. It is still in the experimental stage, with different methods being developed. But we can see or rather smell and taste the exciting results of these efforts. And it’s beating regular coffee with ease.

Read on for a better understanding of fermented coffee and why this artisanal coffee opens up a new chapter in the story of Third Wave Coffee.

Fermentation is part of the post-harvest coffee processing

Fermentation is already part of the post-harvest processing of coffee cherries and always has been. The ripe coffee cherries undergo natural fermentation immediately after harvest during the initial processing stage. The harvested cherries are left to dry in the sun (natural process) or soaked in water to remove the fruity pulp and mucilage (washed process). During this short period, a coffee fermentation process occurs naturally, helping to break down sugars and develop the coffee’s flavor profile. However, with that standard fermentation process alone, the coffee has not yet earned the “Fermented coffee” badge.

A separate, carefully controlled fermentation step must follow the initial processing. 

But before we delve into how fermentation is used in artisanal coffee, it’s essential to understand what fermentation is.

Understanding Fermentation

Fermentation is a natural metabolic process where microorganisms like yeast (fungi) or bacteria convert sugars and starches into other compounds, including acids, alcohol, and carbon dioxide. 

Fermentation has been used for thousands of years in many cultures worldwide. It was not only a preservation method but has been used to create many kinds of foods with amazing flavors. Think sourdough bread, yogurt, a wide range of cheeses, sauerkraut, kimchi, and salami, to name just a few. Alcohol in the form of beer or wine is a product of fermentation as well and has been an important recreational drink throughout history.

Fermentation can start naturally with the bacteria or fungi surrounding us in nature. However, strict control over the process is necessary for a consistently good product. It is particularly important to prevent the growth of unwanted microorganisms that can ruin the taste of your product.

Fermentation to create artisanal coffee

Artisanal coffee, also known as third-wave coffee, is a segment that focuses on high-quality, specialty coffee. Coffee enthusiasts have redefined their favorite drink as an artisanal product rather than a commodity. It became much like the sophisticated culture of wine. This shift in perspective has led to a surge in the popularity of artisanal coffee, with dedicated farmers, roasters, and cafés worldwide striving to offer the best quality brews.

The additional step of controlled fermentation, borrowed from age-old culinary techniques, has opened a whole new world of flavors and aromas in coffee. It opens a new dimension of coffee enjoyment.  

Controlled fermentation is a deliberate and complex process initiated after the initial processing and requires deep knowledge, experience, and craftsmanship. The green coffee beans that have already gone through the initial fermentation are soaked in water, combined with specific strains of bacteria or yeast, and left for 24 to 48 hours under controlled conditions. Often, anaerobic fermentation is used, which is done in an oxygen-free environment. The fermentation process has to be carefully monitored for several variables to prevent the possible development of harmful bacteria.

In this process, it is crucial to select the microorganism to be used for the fermentation. Different microorganisms act differently on the coffee beans and create different flavor profiles. Much experimentation is being conducted on various bacteria and fungi, including yeast used in wine production and even koji. 

Koji is a strain of Aspergillus oryzae, a fungus used in Japan to produce sake, soy sauce, and miso. It has numerous other culinary applications and is widely used in Japanese cuisine. When koji is used in the fermentation of coffee, it adds a unique depth and character. I’m not really sure whether this has something to do with umami, but I would not be surprised.

Another fermentation technique is fruit fermentation. Green coffee beans are put together with fruits in a fermentation vat. This will create a totally different flavor profile with a fruity note.

Unique Flavor Profile

Fermented coffee has a unique flavor profile that varies depending on the type of fermentation used and tantalizes the palate with every sip. Fermentation adds complexity, enhancing sweetness, body, and acidity. It can also introduce new variations of fruity notes to the coffee, transforming the humble bean into a gourmet experience.

It is important to understand that the flavors are already part of the coffee bean. Fermentation unlocks these hidden flavors, enhancing the coffee’s inherent fruitiness and bringing forth vibrant and nuanced flavors of raspberries, stone fruits, and tropical delights.

Nothing is added, like in flavored coffees, where totally unrelated aromas like vanilla, hazelnut, or chocolate are added. Some of these added flavors may not even be natural products but chemically engineered.

Improved Digestion

Fermented coffee has been shown to improve digestion due to better-balanced acidity and a breakdown of complex substances like tannins, which may impact digestion. Proteins and carbohydrates are broken down, making them easier to digest and absorb by the body. Fermentation can also increase the availability of certain nutrients, such as antioxidants and beneficial compounds.
You may experience less bloating and discomfort after drinking fermented coffee. Furthermore, fewer tannins mean less staining of your teeth.

Higher Antioxidant Content

Fermented coffee has a higher antioxidant content compared to regular coffee, thanks to fermentation. Antioxidants help to protect the body from free radicals, which can cause oxidative stress, leading to cell damage and disease. In addition to the increased antioxidant content, fermentation enhances the bioavailability of these antioxidants, making them more readily absorbed by the body. This means that consuming fermented coffee can provide a more potent source of antioxidants than regular coffee.

However, more research is needed to fully understand the specific health effects of fermented coffee and the optimal consumption amounts. 

What about Probiotics?

Fermented foods are known for their probiotics, beneficial bacteria that promote gut health. This is also true in green coffee. However, the probiotics in coffee will probably not survive the roasting process. Coffee beans are typically roasted at high temperatures, which can destroy the beneficial bacteria. Therefore, it is not advisable to rely on coffee as a source of probiotics for promoting gut health.

So, don’t fall for the probiotics hype in coffee. 

Roasting Fermented Coffee

Fermented coffee beans can be roasted just like standard beans. However, the unique and delicate flavor profile may require adjustments to the roasting. The delicate nuances and subtle fruity or wine-like notes that result from fermentation are better preserved with a lighter roast. This ensures that the coffee retains its complexity.

A dark roast can diminish the unique flavors created through fermentation. Dark roasting results in a stronger, bolder taste profile, which will overpower the delicate fermentation flavors. The extended roasting time also reduces the subtleties and complexity of the coffee beans, making a dark roast less suitable for fermented beans.

Therefore, to fully appreciate the intricacies of fermented coffee beans, it is generally recommended to opt for a light to medium roast. This roast level allows the fermentation flavors to shine through and provides a more nuanced and enjoyable coffee experience.

How to Brew Fermented Coffee

Brew fermented coffee like you would brew any other high-quality gourmet beans. I prefer the pour-over method with a metal-mesh filter, allowing the whole range of flavors to pass through into your cup. A paper filter may absorb some of the delicate flavor-carrying oils.

French press and cold brew are also fine. Feel free to experiment with different brewing methods to find the one that best suits your taste preferences.

The Future of Fermented Artisanal Coffee

The trend of fermented artisanal coffee is still in its early stages but is gaining momentum. As more coffee lovers discover fermented coffee’s unique flavors and benefits, the demand for this specialty segment is expected to grow. As this happens, we can expect to see more innovations in fermentation techniques, offering an ever-expanding palette of flavors in artisanal coffee.

Where to get Fermented Coffee?

Innovative, fermented coffee is a rising star in the industry, but it is still not easy to get your hands on it. I once had the chance to enjoy it in the Ignis Café in Tokyo, which specializes in the highest-end coffee from selected coffee producers around the world. If you are in Tokyo, you may want to check out this place. Enjoy their amazing choice of varieties, and don’t miss trying their heavenly Coffee Jelly.

If you are living far from Japan, you are not out of luck. My favorite source of unique quality and single-origin coffees is Volcanica. They source their arabica beans from specialty coffee producers in many countries of the coffee belt.

You can find collection of fermented coffees here.

Colombia wine yeast fermented coffee
Colombia fermented coffee
Mexico Anaerobic fermented coffee

These are three examples of specially crafted fermented coffees.

Final thoughts

The world of coffee is full of surprises and wonders. Fermented coffee is a rising star in the coffee industry. It is pushing the frontiers in the coffee world, going beyond the rim of Third-Wave Coffee.  A magic blend of time-honored fermentation techniques and the modern approach to processing makes this possible.

Whether you prefer fruity, floral, or wine-like notes, there’s a fermented version out there to meet your taste. So why not try it and unlock the secrets of fermented coffee? Let’s embark on this journey to discover the enchanting world of fermented coffee.


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