Coffee Knowledge Base

15 February 2024

The anaerobic coffee bean processing method

The anaerobic coffee bean processing method

When harvesting or picking coffee berries, the beans must be removed from the berry. There are four different methods to do this, and each method may vary from country to country and between regions. There is the dry method, the wet processing or washed method, the semi-dry method, which may also be called the semi-washed, pulped natural, or the honey method depending on the country, and there is the fairly new anaerobic method. Here we will explain the anaerobic processing method. 

Anaerobic Processing Method

To safeguard coffee quality, processing must be done within eighteen hours after harvest. Processing usually takes place in the evening and night following the daytime picking. The processing method is crucial for the flavor in the cup, but no particular method is better or worse than another. Each method, dry or wet, produces a completely different flavor spectrum, and growers often use different methods to create distinct flavor profiles. After processing – and regardless of the method – the beans are always dried because a coffee bean must have less than 12% moisture content before it is suitable for transportation.

The anaerobic method is a very interesting and fairly new one, and a very particular fermentation method. The coffee is only depulped, so not washed, and then mixed in a sealable tank with pulp from another coffee that has completely different characteristics (e.g. another variety, cultivation altitude, height, region, etc.). The tank is then hermetically sealed, so that the fermentation can begin. After the fermentation period in the tank, the beans are taken out of the juicy fruit flesh solution and laid, unwashed, on drying tables. This method is wholly based on the idea that coffee is a fruit. The processor aims to allow the juicy, fruity characteristics of the flesh to absorb into the beans. The acidity, the duration of the process, the material the tank is made of, and the pressure inside it all have important bearing on the outcome.

As mentioned in the beginning there are 4 different types of processing coffee beans. If you would like to know more about the other 3 methods, we recommend you to read the following blogs:
The dry coffee bean processing method
The washed coffee bean processing method
The pulped natural coffee bean processing method