FERMENTED COFFEE: WHAT IT IS AND HOW TO MAKE IT AT HOME

Fermentation adds compelling and complex flavors to many of our favorite foods and drinks, coffee included!

The coffee community loves experimenting, always coming up with fresh ways to create and serve their favorite drink. Fermentation is one of many ways to explore new and exotic coffee flavor profiles.

What is fermented coffee? Fermented coffee, sometimes called cultured coffee, refers to green coffee that has been fermented while still in cherry form, after it’s been pulped and the husk has been removed before roasting. The term fermented coffee can also refer to another thing, and I’ll explain it as well in this article.

For starters, fermentation is a traditional part of coffee bean processing. In a more modern example, baristas are exploring the fermentation of brewed coffee – a unique drink you can even make at home!  

What Is The Fermentation Process In Coffee?

Perhaps I should start with a quick definition of fermentation. It’s the process that occurs when yeast and bacteria feed on the carbohydrates in a substance, breaking down the sugars and starches into acids and alcohols (1). 

Fermentation produces characteristic flavors, like tart, sour, pungent, or funky. Think about fermented foods like kimchi, kombucha, or sourdough.

Coffee undergoes its first natural fermentation immediately after the coffee cherries are harvested. Omnipresent yeast and bacteria in the environment feast on the sweet pulp and mucilage around the coffee seeds. This is particularly important in the washed coffee processing method, but it occurs to some extent no matter how the beans are processed.

Controlled Fermentation Techniques

After the beans are processed, some coffee producers put the resultant green coffee beans through a controlled and intentional fermentation process. This is the type of fermentation we are usually referring to when we talk about fermented coffee. It is sometimes called cultured coffee.

They are left to sit for one or more days and must be carefully managed to avoid the drop from delicious to rancid. After the fermentation, the beans are washed, dried, and shipped to a roaster. 

In the currently trendy anaerobic fermentation, the process is carried out without oxygen, which slows it down and creates a unique flavor profile (2). Flavors can also be influenced by altering the tank – for example, barrel aging coffee – or adding extra ingredients like fruit.

Why Is Coffee Fermentation Important?

The main reason coffee is fermented is to create unique and exciting flavor profiles. Some producers even use it to add value to sub-par beans. But it has a few extra benefits for consumers.

What Does Fermented Coffee Taste Like?

Fermented coffee beans can have a variety of tasting notes, depending on the type of coffee beans used, the roasting profile, and the brewing method.

Most often, the process results in bright and tart notes with a fruit-forward acidity. Many fermented coffee I’ve tried tasted of tropical fruits, ripe berries, or even sour candies, though you’ll find others with darker chocolate and wine notes.

Is Fermented Coffee Healthier?

Drinking coffee already has significant health benefits, and none of these are diminished by fermenting the green coffee beans (3). Additional health benefits conveyed by the fermentation process are more anecdotal and less science-backed. 

Many sufferers of IBS and other stomach problems report having an easier time digesting fermented coffee, perhaps because the microorganisms involved in fermentation have already done some of the digestion. The impeccable control required to manage the fermentation process also means that fermented coffees are less likely to develop mold or other contaminants. Lastly, fermented coffees are lower in tannins, making them less likely to stain your teeth.

Just don’t expect fermented coffee beans to be rich in probiotics like kefir or kimchi. Those are destroyed in the roasting process.

What Is Fermented Brewed Coffee?

Fermented coffee occasionally refers to a coffee drink in which coffee is brewed with regular beans before undergoing a fermentation process. 

The process for making this drink is the same as any fermentation process. You just need the right bacteria and something for it to eat (sugar). Nature takes care of the rest. The most common ways to add bacteria for fermenting coffee are kefir, kombucha, or beer yeast. 

How To Ferment Coffee At Home

The kombucha method is the easiest way to ferment regular coffee at home. You’ll need to buy or make a kombucha SCOBY to kickstart the fermentation process. Let me show you how.

Making Fermented Coffee Step-By-Step

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

Final Thoughts

I love learning about innovations in the coffee world, particularly when they result in novel and compelling flavors in the cup. If you’re a fellow specialty coffee fan, I assume you feel the same way.

Now that you know about fermented coffee, I hope you’re excited to explore the unique flavor possibilities that arise from the technique. And if you’re feeling particularly adventurous, give the home brew coffee kombucha a try!