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What You Need to Know About Fermented Coffee

The coffee community loves to experiment, continuously coming up with new ways to create and serve their favourite drink. One of the more out-there kinds of coffee you might have seen is fermented coffee.

Fermented coffee can refer to two different things: beans and brewed coffee. It’s not as confusing as it sounds, and we can even show you how to make it at home.

fermented beans vs fermented coffee
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Fermented Beans

You’re probably asking yourself – isn’t coffee usually fermented? And you’d be right. Wet-processed beans will undergo some natural fermentation as they soak.

When we talk about fermented beans, however, we’re referring to beans that have undergone a deliberate and controlled fermentation after they have been dried – i.e., as green coffee beans.

After the beans go through this fermentation, they are roasted as usual, ready to be brewed as you choose. You’ll see them sold as either fermented or cultured coffee beans.

The coffee fermentation process

Fermentation is a natural chemical reaction that’s the key to some of the best things in life, like cheese and wine. But the difference between delicious and rancid is careful control of the process.

The primary method starts with green beans that have already been processed – either washed or natural. They are then soaked in water, inoculated with specific bacteria, and left to sit for 1-2 days. After the fermentation is complete, the beans are washed and dried to be ready for roasting.

Other methods of fermenting coffee include barrel aging or adding ingredients like fruit to the fermentation tank.

Why is coffee fermented?

Fermented coffee might seem like a fad, but the act of fermentation promotes some notable and positive changes in the beans. As well as having the regular health benefits of coffee, fermentation makes the drink easier to digest, safer from harmful bacteria, and lower in tannins (1). It also enhances some of the flavours in coffee.

[it helps] the bean imbibe different flavours and produce more complex tasting notes to the same coffee.

Coffee fermentation does add certain characteristics to the taste, but the final flavour will still depend on the type of beans you start with and the brewing method you use.

Fermented Brewed Coffee

The other way you’ll hear the term fermented coffee used is for a coffee drink. This drink is brewed coffee made from regular beans, which then goes through a fermentation process. Such a method creates a unique tasting beverage that’s tangy and even slightly carbonated. It’s also full of probiotics that promote good gut health.

The process for making this drink is, in theory, the same as any other fermentation process. You need the right bacteria and something for it to eat (sugar), then let nature do the rest. The most common ways to add the right bacteria for fermenting coffee are with kefir, kombucha, or beer yeast.

How to ferment coffee at home

The easiest way to ferment coffee at home is with the kombucha method. If you’ve never made coffee kombucha before, the most critical step is buying or making a kombucha SCOBY (2). This is what kickstarts the fermentation process.

WHAT YOU NEED

  • 946ml quarts of brewed coffee
  • 1/2 cup of sugar
  • Kombucha SCOBY

AT A GLANCE

BREW TIME

3-5 days

Glass Jar

Instructions:

  1. Combine the sugar and coffee in a glass jar and stir until the sugar is dissolved. Allow cooling.
  2. Add the SCOBY and cover the jar with a cheesecloth or coffee filter. Use a rubber band to secure.
  3. Let the mixture sit at room temperature for 3-5 days, away from direct sunlight. Check daily for any signs of rancidity.
  4. Once you’ve achieved the desired taste, remove the SCOBY and store your coffee in the fridge.

If you’re considering fermenting coffee for health benefits, you might want to check out our guides for healthy coffee recipes and ways to make coffee healthier for you.

FAQs

Yes. You can ferment coffee beans at home, but you will need the equipment and know-how to carefully monitor the fermentation. You’ll also need a way to roast the beans before brewing.

Fermented coffee grounds have nothing to do with coffee and everything to do with alcohol! Scientists in Portugal discovered a way to turn used coffee grounds into a 40% spirit – just don’t try this one at home (3).

No. Brewed fermented coffee doesn’t go bad in the traditional sense. However, it can become unsuitable for drinking. Even if stored in the fridge, the fermentation will continue slowly, and after 2-3 months, you may end up with coffee vinegar. Fermented beans have the same shelf life as regular beans.

  1. Fermented coffee: Why it’s healthier and Tastier than regular coffee. Pure Kopi Luwak. (2018, July 10). Retrieved October 20, 2021, from https://www.purekopiluwak.com/fermented-coffee/
  2. Christensen, E. (2019, June 5). How to make your own kombucha scoby. Kitchn. Retrieved October 20, 2021, from https://www.thekitchn.com/how-to-make-your-own-kombucha-scoby-cooking-lessons-from-the-kitchn-202596
  3. Schultz, C. (2013, August 5). These heroic scientists turned used coffee grounds into booze. Smithsonian Institution. Retrieved October 20, 2021, from https://www.smithsonianmag.com/smart-news/these-heroic-scientists-turned-used-coffee-grounds-into-booze-23032042/
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I love trail running, rock climbing, coffee, food, and my tiny dog — and writing about all of them. I start every morning with a fresh Americano from my home espresso machine, or I don’t start it at all.

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