Coffee Fermentation: A Guide

Curious to learn more about coffee fermentation or what makes Cultured Coffee different? If either case is true, you've come to the right blog post.

We think it's time to demystify what coffee fermentation is all about.

A Brief Lesson In Coffee Anatomy...

But first, we'll need to start with anatomy.

Coffee beans are actually the seeds of a cherry-like fruit tree. The small, round fruit looks like a cherry and turns red when it's ready to be harvested, which is why coffee fruit is called coffee "cherries." 

Coffee cherries are made up of several layers, shown below, that range in texture from the tough, bitter outer skin and slimy fruit pulp through to thinner, more papery layers encasing each bean. 

Coffee cherry husk isn't typically used in the coffee making process, though some speciality drinks like cascara are made from the coffee fruit instead of the bean.

The green beans on the inside of the cherries are what get roasted to make coffee! However before that happens, the coffee beans (or seeds) have to be extracted from the thick cherry husk around them. 

Processing

Once coffee cherries are harvested, they're typically manually sorted and visually processed on the farm to select the best fruit. This is when fermentation can come into play. It's used to remove that tough cherry husk, which is referred to as "processing". 

There are two main methods for processing coffee cherries: "wet" and "dry."

Dry processing is most commonly used in regions with limited water resources or arid conditions. Coffee cherries are spread out on large "beds" to dry in the sun. This dries the thick outer layer and turns the cherries from a red to dark brown color. At this point the outer layers can be hulled off to remove the green beans inside. 

Wet or "washed" processed coffee harnesses a form of natural spontaneous fermentation triggered by soaking coffee cherries in water after harvest. The soaking process starts to make the coffee cherry fruit ferment. Each layer inside the cherry starts to naturally peel away from the beans. This makes the cherry husk and pulp layers easier to remove.

Beans are then steeped in large troughs of water to remove any mucilage (fruit pulp) still stuck to the parchment layer around the beans. Green coffee beans are then set out to dry on large beds like the one below in Uganda.

Many believe the wet or washing process lends a smoother, silkier mouthfeel to the coffee versus dry processed beans. However techniques are often steeped in local tradition or tied to climate.

For that reason tasting a variety of processed coffees is a fun way to taste-test your way around the coffee growing world. 

Fermentation

While wet processed coffee may use natural fermentation to remove the cherry material from around the bean, the health benefits from this fermentation are limited, vary from bean to bean and largely unmonitored.

Once coffee beans are roasted ready for sale, very little of the coffee you buy at your local café or store will have many fermentation benefits left inside. 

Controlled Fermentation

However that's where eatCultured and Cultured Coffee come in. We've developed a special technique for fermenting beans green coffee beans after they've been harvested, whether they've been wet or dry processed on the farm.

Honed by years of research our controlled fermentation, which is closely monitored by our team with each new batch of coffee, means each green bean undergoes a consistent level of fermentation. This process ensures a consistent level of health benefits in each bean before roasting. 

Our controlled fermentation produces a smoother tasting, more digestible and energy-supporting coffee all thanks to the humble microbe. A consistent level of health benefits get locked in to each bean even after roasting. 

Learn more about eatCultured's first healthy fermented product: Cultured Coffee