Fermentation is an important step in the processing of coffee beans. After the coffee cherries are harvested, they must be processed to remove the outer layers to reveal the coffee beans inside.

The processing step used to remove the mucilage left on the bean after the cherry is removed.

One of the most common ways to process the cherries is called the aerobic or wet method, which involves fermenting the cherries before removing the outer layers.

Aerobic: Occurs when oxygen is present. Ambient humidity mixed with the cherry’s natural sugars and water. This can begin immediately after the cherry is picked.

Anaerobic: Cherry’s are put in a tank and covered with water, removing their contact with oxygen.

During fermentation, enzymes in the cherries break down the mucilage and fruit flesh surrounding the beans. This process can take anywhere from 12 to 48 hours, depending on the specific method used. The temperature, humidity, and time are all factors that can influence the fermentation process.

Canterbury Coffee Assistant Roastery Manager, Tim Cole.

Fermentation is a crucial step in the coffee production process because it helps to remove the sweet, fruity flavours of the cherry and reveals the flavours of the coffee bean itself. Fermentation also helps to remove any impurities or defects in the beans, which can improve the overall quality of the coffee.

As well, coffee fruit can start fermenting before it’s picked, while it is still on the tree. See this article on fermentation at Cafe Imports.

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