Coffee

How Coffee Bean Processing Methods Affect Your Latte

It’s sometimes hard to comprehend that the delicious black liquid that ends up in your coffee cup comes from a bean. Whether it be cold brew coffee or a classic cafe au lait, they all come from the same bean source. However, despite their similar humble beginnings, there is a lot of diversity in coffee. Each cup of coffee has a long history behind it. A journey from bean to cup with lots of different steps along the way. 

There are a number of ways that coffee tastes are changed post-harvesting. The main way we at 80 Stone do this is through coffee roasting at our coffee roastery and different extraction techniques at our Elephant and Castle Cafe. These are all relatively late in the lifespan of a coffee bean, you can affect the end product sooner in the process. 

When farmers are harvesting the coffee, it can go through several different processing methods. The three main methods of preparation are natural, semi-washed (or pulped natural), and washed. Let’s explore the makeup of a coffee bean and how coffee producers can affect how coffee is processed at bean level. 

The Anatomy of a Bean

So where exactly does the journey of a bean begin? It all starts with a plant, a cherry to be exact. The beans we roast, grind, and brew to make coffee are the seeds of a fruit, so our beloved coffee originates as a plant. The bean itself comes from a bright red coffee cherry. The coffee plant produces coffee cherries, and the beans are the seeds inside.

They are surrounded by a soft layer of mucilage and a thin skin known as parchment. Once the cherry is harvested, the seeds must be separated from the cherry without losing the aroma that is contained within the mucilage. Essentially, the beans are removed from the fruit whilst attempting to keep the natural coffee flavours intact.

However, this is easier said than done. Over time, different ways of achieving this extraction have developed to best separate the inner seeds from the fruit. This is where the different processes come into play. 

On the inside of the coffee cherry, there are usually two seeds which are the actual beans you know and love. Interestingly about 7% of the picked cherries contain only 1 seed and it is called peaberry.

Coffee Bean Processing Methods

This step comes after the harvesting and picking stage of production. Coffee processing removes the fruit from the seed; skin, pulp, parchment, and silverskin slough off to reveal a beautiful bean. 

What is interesting is the different methods actually affect the end taste of the coffee. They can produce a very different taste profile, even if the coffee comes from the same country and the same farm. Knowing how the bean has been processed can help roasters and general consumers determine how they will use it. 

This is what we have been experimenting with at the roastery, with a new range of beans roasted in the same way but processed in 2 of the 3 different methods. The processes we are  using for this new range are the washed and natural processes. 

The Wet Process

The wet method, or “washed coffee processing,” is where the fruit covering the beans is removed before they are dried. The process requires a substantial amount of water and due to this, this process mostly occurs in countries which are abundant in water. 

The cherries are firstly picked and then washed to remove any excess material. The pulping stage then begins, which is where the beans are removed from the coffee cherry by a pulping machine. The removed pulp is usually placed back in the plantation as fertiliser. The coffee beans are left to ferment in a fermentation tank, the fermentation process breaks down the sugar and prepares the beans for the next stage of processing. 

After that the coffee is washed once again to remove the decomposed mucilage and then dried either in patios or raised beds.

How This Process Affects Taste

This process often creates a bean that is much cleaner and brighter in taste than the unwashed method. Wet processed coffee doesn’t exclusively give clean tasting coffee, all methods of production can achieve this. The wet processing method is just easier to achieve this kind of tasting bean due to the ease of it in comparison to the others. 

The Pulped Natural/Semi-Washed Process

This hybrid technique is also known as the honey coffee process pulped natural. It’s essentially a middle ground between the dry and wet processing methods. 

The half pulped process involves removing the skin of the fruit before letting the coffee dry with almost all of the pulp still on the beans. The contrasts the other techniques where during the natural (or dry) method, the beans are dried entirely in their natural form, while the washed (or wet) process sees all of the soft fruit residue, both skin and pulp, removed before the coffee is dried.

Farmers have been experimenting with this process which leads to many processing involving techniques which may be considered a variation of pulped natural, such as the black honey, red honey or white honey process. This is when a portion (but not all) of the fruit pulp is removed by parchment remover machines before drying. In general, the difference between each of the techniques is the amount of mucilage (or mesocarp) that is removed after the peel. 

How This Process Affects Taste

Beans created using the semi-washed process are an attempt to combine the best of both worlds of the two methods. Many prized coffees are produced through this method.

The Dry Process

Known as “natural coffee processing” or the “dry process,” this is the oldest preparation method and has been in use for hundreds of years. In this process, the newly harvested coffee cherries are sorted and left to dry in the sun. This occurs mostly in countries where water is less readily available and are left to dry wherever possible. 

Sorting must first take place in order to eradicate any damaged, unripe, or otherwise defective cherries. Since the cherries are not washed in the same way as they are in the wet method, excess waste like soil and twigs is usually removed by hand using a sieve.

The coffee cherries are then dried and are turned by hand to ensure even drying and prevent mildew. It may take up to 4 weeks before the cherries are dried to the optimum moisture content, depending on the weather conditions Because the beans are still covered by their protective layer of cherry it can take much longer for the coffee to reach the goal of a moisture level of less than 12.5%.

After the cherries have properly dried, they are then held by large coffee silos and sent to a mill. The mill will hull, sort and grade the coffee, and the hulling process will remove the fruit.

How This Process Affects Taste

Dry processed coffee has its own unique flavour. The unwashed method creates a coffee that is heavy in body but remains sweet, smooth, and complex. In many cases, countries that have very dry climates like Indonesia, Ethiopia, and Brazil use this method. The large amount of sunlight in these areas helps to dry the beans effectively. 

Try The Processes For Yourself

Our wholesale coffee bean selection is always looking to expand and you can soon try these processing methods from 80 Stone. Keep an eye on our beans page for the new range to land so you can experiment with the different processing methods yourself. Get in touch today to learn more!

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