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What Is Fermented Coffee?

fermented coffee kombucha

Wine and beer take the spotlight when talking about fermented drinks, but kombucha, that is, fermented tea, has recently been gaining popularity. Fermentation is traditionally used to increase a beverage’s alcohol content, but it also creates a concoction full of helpful probiotics and bacteria.

It is natural to wonder if you can ferment coffee, and the simple answer is yes! Fermented coffee is similar to fermented tea, and many coffee companies are experimenting with coffee kombucha. In this article, we’ll tell you everything you need to know about fermented coffee. We cover what fermented coffee is, who should try it, and some of the health benefits. Let’s get started!

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What Is Fermentation?

Don’t worry—we won’t turn this into a science class, but it is important to understand what fermentation is generically before we can meaningfully talk about fermented coffee.

Fermentation is the process of breaking down sugar used by yeast and other bacteria as a food source. As the yeast feeds on sugar, it produces alcohol as a byproduct. The longer the fermentation process runs, the less sweet the resulting water will be and the higher the alcohol content. Interestingly, fermentation is an autoregulating process since some forms of yeast cannot survive above a certain threshold of alcohol concentration. Brewers use this fact to control the alcohol content of beer reliably and consistently.

Fermentation and Coffee

So, where does coffee enter the picture? When coffee cherries are harvested and the beans prepared, a key part of the process is fermentation. Traditionally, coffee cherries were naturally processed and allowed to dry in the sun with the coffee cherry fully intact. During the drying phase, fermentation occurs naturally and imparts sugary sweet flavors to the beans. In modern coffee farming, it is more common to completely remove the coffee cherry and induce fermentation artificially by soaking the beans in water. This type of fermentation is an essential element of coffee production, but not what most people mean when they talk about fermented coffee.

washed coffee
Image Credit: ngtghaivanamg, Pixabay

When we say fermented coffee, we’re referring to fermenting brewed coffee, akin to how wine is sort of like fermented grape juice (we apologize to any wine experts for the oversimplification). Fermenting coffee after brewing makes a kombucha-like drink that most people creatively call “coffee kombucha.”

How Does Coffee Kombucha Taste?

Fermenting brewed coffee produces a drink with many similarities to traditional kombucha made with tea. Coffee kombucha has a tangy quality to it, with a velvety smooth mouthfeel, surprisingly low acidity, and a tiny bit of carbonation-like bite to it.

Much like kombucha made with black or green tea, coffee kombucha retains most of the flavor from the brewed coffee base. We tend to like medium roasts for coffee kombucha, but light roasts also work well if you can get the extraction right. Dark roasts aren’t the best choice for fermented coffee since the bold flavors can easily overpower the more subtle effects of fermentation.

coffee-pour in shop pixabay
Credit: minhthai0105, Pixabay

How to Make Fermented Coffee at Home

If you're interested in whipping up a batch of coffee kombucha yourself, here's a quick and easy recipe to start with. Making coffee kombucha is no more labor-intensive than making regular kombucha with tea, but there are a few pitfalls you need to be aware of.
5 star average
Prep Time 4 mins
Resting Time 7 d
Total Time 7 d 4 mins
Course Drinks
Cuisine American
Calories 10 kcal

Equipment

  • Glass or ceramic container
  • Coffee filter or cloth
  • Rubber band

Ingredients
 

Instructions
 

  • In a non-porous container—glass or ceramic is a good choice—combine 2 quarts of freshly-brewed hot coffee with ½ cup of sugar. Stir until the sugar dissolves and let the mixture cool to room temperature.
  • Add the SCOBY and cover the container with a coffee filter or cloth. Make sure the container is tightly sealed by securing the cover with a rubber band.
  • Leave the mixture at room temperature out of direct sunlight for at least 7 days. Be sure to monitor the kombucha for signs of rancidity daily.
  • After 7 days, taste small amounts of the kombucha through a straw once per day until you reach your desired taste.

Notes

If you're unfamiliar with the term SCOBY, it is an abbreviation for "symbiotic culture of bacteria and yeast" used for making fermented drinks.
Coffee is more acidic than tea and contains natural oils from the coffee bean. Both of those factors combine to increase the chance of coffee kombucha spoiling during the fermentation process. It is imperative that you carefully check your coffee kombucha for signs of rancidity before you consume it. If the kombucha has a funny smell or look, discard the entire batch and try again.

Nutrition

Calories: 10kcal
Keyword fermented coffee

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Conclusion

Fermentation has always been an essential part of coffee processing but fermenting brewed coffee is less common and unfamiliar to most people. In recent years, there has been a resurgence in the popularity of coffee kombucha, and many coffee companies are experimenting with producing fermented coffee.

Fermented coffee has a unique taste, and making your own is a fun weekend project. Luckily, it’s not hard to make coffee kombucha, and we hope our simple recipe is enough to pique your interest and inspire you to try it out for yourself.


Featured Image Credit: Fotema, Shutterstock

Sean Brennan

Sean’s obsession with coffee started when he received his first French press as a gift almost ten years ago. Since then, his love of coffee – and the number of coffee gadgets he owns – has grown considerably. A scientist by training, there is no stone he has left unturned in the never-ending quest for the perfect cup of coffee. He has spent many hours tuning his pour-over technique, thinking about how to best compare grind quality, and worrying about whether the Nicaraguan or Kenyan beans will make the best cold brew. These days he favors the Hario V60, and starts each day by hand grinding his coffee before enjoying a cup prepared with care and attention to detail.

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