The Coffee Cherry
Coffee beans are actually the seeds from a coffee cherry.
Like most fruits, the coffee cherry is made up of layers, approximately six layers.
Starting with the outer skin, then the pulp, mucilage, parchment, silver-skin and the all important beans in the middle.
The image to the right, shows some freshly picked, ripe coffee cherries. To make coffee we need to get to the seeds in the middle, for it is these, that once roasted, produce the flavoursome drink we all know and love.
The image above shows an approximation of the layers within a coffee cherry.
For coffee, we are only after the beans in the centre (generally there are two beans in each cherry).
Skin / Pulp: Coffee seeds are covered by flesh, much like a cherry you might eat, although in coffee there are normally two seeds (two coffee beans) rather than the single seed within a normal cherry.
Mucilage: The next layer of the coffee cherry is called the mucilage, common in many seeded fruits. It is sweet sticky layer covering each of the coffee seeds. This layer is sugary and so is also known as the "honey" layer (hence the honey process)
Parchment: The next layer down is called the mucilage - when dried it loosely resembles parchment paper.
Silver skin / Chaff: The next layer into the cherry is a very fine layer called the silverskin which has a silver sheen to it, which is where the name originates. This layer remains on the seeds (coffee beans) and is removed by the roasting process and is often referred to as chaff.
Seed / Coffee Bean: Finally - we get to the gold.... the coffee beans! Most coffee cherries have two "half" seeds inside. There are also "Peaberry" beans in which only one seed has formed. Only a small percentage of coffee is classed peaberry - some of this is sorted and sold as a distinct coffee, although often you will find some in your normal coffee.
There are four main methods of processing coffee cherries into beans ready to be roasted . The processes differ in the way the layers are removed before the beans are dried. Each processing method gives slightly different characteristics in the resulting coffee.
What do these different processes mean to you? Well for a start, don't be dazed by them, they are just the method of getting to the all important beans in the middle. However, you may find over time that you prefer a certain bean varietal (we'll cover these on another page) processed in a certain way, roasted carefully like we do at Waveney Valley Coffee. Armed with this information, you can more readily select different coffees that you know you will like.
After all, good coffee isn't cheap, it is better to understand the coffee you prefer so you can select coffee that you are most likely to enjoy. That said, always try new coffee types, processes and regions of origin. Coffee is like wine, where every season is different.
Natural Process (dry)
This is one of the oldest methods and no layers are removed before the beans are dried. The coffee cherries are picked, sorted and dried before the beans removed.
In this process the cherries are harvested and dried, it is as simple as that. It is especially useful in regions where little or no water is found. Drying is slow and can take a month or more for the cherries to dry. There is much skill and a certain amount of luck that the fruits do not spoil during the drying process. It is only used in regions that are very dry. However the advantages of this method are that the resulting coffee can retain many of the more subtle and fruity flavours.
Once dried the cherries are put through a mechanical process known as "milling" to remove the other layers. There is a risk of damage to the beans if these mechanical processes are not set up correctly.
Washed Process (wet)
Another common method is to remove the skin, pulp, and mucilage using a mixture of water and fermentation.
Firstly the raw cherries as placed in a de-pulper and the outermost layers are removed. The beans are then placed into fermentation tanks and natural enzymes 'ferment' the mucilage where the sugar breaks down. There are a number of methods used to ferment and this process can take anywhere from a few hours to a week. The skill in this method is very important to know when fermentation is complete, over due the ferment and the resulting coffee will taste off. This process produces fine coffee but uses quite large amounts of water. Coffee produced in this manner loses some of the fruitier flavours but the coffee retains good flavour and some nice acidity.
The other advantage around wet processing is that the under ripe and bad cherries are easily removed during the processing.
Pulped Natural (wet)
Another wet process which uses high pressure water to remove the skin, pulp and mucilage. This process is avoids the need for the fermentation stage. It is a common process in some countries and although the coffee is consistent, there is not the flavour development found in either the dry process or the normal washed process where fermentation imparts flavours to the beans before drying.
The skin and pulp are removed, but some or even all of the mucilage is left behind. The mucilage which is also known as 'honey', is left on during the drying process. This results in a sort of half way house between a natural and washed process.
Just to confused things even more, there are levels of "honey", yellow, red, back. The darker the honey level, the greater potential for more complex flavours to develop during the process.
All said and done, there are good coffees to be found in each process. You may find you prefer coffee that is processed in one manner and therefore its nice to both understand a little bit about the process and what those labels on bags of coffee are really telling you.