Category Archives: Coffee process

Hybrid Processes

Hybrid processes are basically a combination of natural and wet processing though the exact methodology varies per region. This combination will bring together the economic benefits of the natural process with the speed of the wet process. For the coffee cup the hybrid process results in a better body than for washed coffees but cleaner character than for dry processing.

There are two main methodologies that fall under hybrid process: the pulped natural or honey (miel) process and the semi-washed/wet-hulled process. The first is mostly used in Latin America and the latter in Indonesia.

The pulped natural or honey (miel) process

This method was developed in Brazil under the name pulped natural and it is used extensively in Central America where it is known as the honey or miel process (miel means honey in Spanish). In Brazil the idea was born to produce coffees with high cup quality using less water than used in the wet process.

The process starts in the same way as the wet processing: after picking, the coffee is mechanically depulped to strip it from the outer skin and the pulp.  Equal to the wet process the mucilage remains attach to the coffee beans.  From this point the process changes: instead of going to fermentation tanks as in the wet process, the coffee beans go straight to drying patios or drying beds. With less pulp surrounding the beans the risk of defects seems smaller than in the naturally dried coffee, however the mucilage is moist and sticky which makes a perfect setting for rot and decay. Hene, lots of attention must be paid during the drying period that can take up to two weeks. The beans must be gently moved every certain time, sometimes even every hour. With the mucilage still covering the seeds there is still enough sugar left around to increase the body and sweetness in the coffee beans.

Depulping machines can be controlled to leave a specific percentage of pulp on the beans. According to this percentage the resulting coffee is referred to as one hundred percent honey or “Black honey”, a “red honey” has a lower amount of mucilage and “yellow honey” implies nearly all of it is removed. During the drying period the mucilage turns darker there fore the names used to the different percentages of mucilage remaining come from the  color of the beans while drying. It is easy to understand looking at the pictures below.

Black honey (varietal Venecia) at Finca Naval, Costa Rica
Red honey (front) and yellow honey (back) at Finca Naval, Costa Rica
Yellow honey at Finca Mate, Honduras

The black honeys have a higher concentration of sugar. They should receive less light and dry slower than other processes. The yellow honey has the lower concentration of sugar thus it is easier to handle but it receives more light and will dry faster.

In combination with depulpers, nowadays mechanical demucilagers can help to strip the mucilage through the use of rough bristles or the use of water pressure.

The flavour profile of honey processed coffee: plenty of acidity that is perceived as being more gentle due to more sweetness in the coffees, a syrupy sweet body and a wide span of flavour characteristics.

Yellow honey at Cafe Directo. Costa Rica

The semi-washed/wet-hulled process

This process is common in Indonesia and results in very distincti flavours. After picking, the coffee is depulped and then briefly dried to a moisture content of 30-35 percent (instead of the usual 11-12 per cent). The coffee is then hulled, removing the parchment and completely exposing the coffee bean as when it is ready to be roasted. The naked beans are then dried again to low moisture content. This second drying gives the beans a deep swamp-green colour. Semi-washed coffees have a lower acidy and more body than other coffees but they also develop flavours that for many of us are rather unpleasant such as wood, tobacco or leather.

Go for it!

If you have the chance to taste a honey processed coffee go for it, it would not disappoint you especially if it comes from Central America, where they have embraced and perfected the process. My suggestion, try our yellow honey (red Catuai) from Cerro de Jesus, Nicaragua 😉

Big thanks to Armando Navarro, Gerardo Arias, Mixael Lemus and Ever Alvarado for the photos of honey process in their farms.

The Washed process (or Wet Process or Lavado)

The first step in the process is that the coffee cherries are sorted either by hand on tables or by placing them in a flotation tank where the ripe cherries will sink and the unripe ones will float. The next stage is the so-called depulping where the coffee cherry is split and squeezed to remove both the outer skin and the fruit pulp. This can be done by using a mechanical depulper (sort of a large blender) or simply by jets of high-pressure water.

Mechanical depulper in Guatemala

After depulping the coffee beans are still covered by a resilient sticky layer called mucilage. Its tenacity is due to a combination of sugars and pectin and the best way to remove it from the coffee beans is by means of fermentation.

Beans with mucilage
Left over cascara after depulping

The beans are placed tanks for 12 to 72 hours to ferment.  During this period the pectin in the mucilage is broken down through the activity of enzymes. The duration of the fermentation depends on a number of factors such as altitude, ambient temperature, volume of coffee, type of beans. The fermentation period will also affect the coffee flavour so knowing when to stop is crucial. If the fermentation takes too long unwanted flavours can creep in, but when properly timed washed coffees can develop a distinctive clean acidity. “Cleanliness” is a term used in coffee to indicate the absence of any negative flavour, such as  harshness or astringency.  In Kenya it is common to do two fermentation periods to achieve certain quality of flavour or appearance. These coffees from Kenyan are bright and fruity.

Fermentation tanks

Following a wash with clean water the beans are place to dry under the sun.  As with natural dry processed beans (see http://www.engrano.nl/blog/2017/02/13/natural-or-dry-processed-coffee/) beans can be dried in patios, lying on the ground or placed on raised tables. The tables have the advantage of lifting the beans from the ground so that contamination with stones or other plants can be avoided and improving air circulation around the beans whilst high temperatures should be avoided. During the drying process the beans should be gently rotated. Farmers also take the opportunity to sort through the parchment-covered coffee beans by hand removing the damaged ones. Depending on the weather conditions the drying period could take up to 21 days.

Parchment-covered beans drying on the ground and at raised beds

Once dry, the parchment-covered beans look light beige coloured. To remove the parchment the beans are moved to a dry mill after which comes sorting and packing of the green beans.

This process is more expensive than the natural and hybrid process. It involves a precious and sometimes scarce resource: water. On one hand, removing the mucilage greatly reduces the chance of something going wrong during the coffee processing which may lead to a higher value for the coffee. On the other hand, the wet process is not a warranty of quality. Defectives beans are not uncommon and fermentation can be unpredictable. An environmental concern about this process is due to the eventual fate of the waste water, which can be toxic.

Usually the flavour of washed coffees can be described as a clear acidity profile, light-to-medium body, usually with citrus tones. If you have the opportunity to taste coffees from the same origin but that have been processed both as washed and as dried and you will notice the difference!

Washed beans (left) and natural beans (right) both from Cariamanga, Ecuador – green
Washed beans (left) and natural beans (right) both from Cariamanga, Ecuador – roasted

Processing coffee

The coffee that we enjoy so much is prepared from the roasted seeds of a fruit. What we call a coffee bean is in reality a seed nestled inside a coffee cherry. These cherries are at their sweetest when they are ripe. They should then be picked from the plant and processed as soon as possible in order to keep all their potential. It is necessary to process the coffee cherries to prepare the seed for roasting.

Processing coffee has two stages: the preparation stage and the dry milling. The steps followed during the preparation stage vary per region or even per farm. The main methods are dry process (also known as “natural”) and wet process (also known as “washed”). Nowadays it is in fashion to use a combination of both techniques, which is known as pulped-natural, semi-washed or honey. Maybe a small scheme will make it easy to understand.

I once wrote about the natural process, you can check it out here

http://www.engrano.nl/blog/2017/02/13/natural-or-dry-processed-coffee/

I will write about the washed and semi-washed process in future posts.

In the preparation stage the coffee transforms from the cherry stage into the parchment stage. In the parchment stage the coffee beans are dry but still covered with a protective layer. The steps in this preparation stage will vary depending on the process method: Wet, dry or in between, but they all prepare the coffee cherry for the dry mill stage. The preparation stage is many times refers to as “wet milling” which is slightly misleading since in some of the processes there is actually very little water involved.

During the dry milling or hulling the dry skin (from natural process), parchment (from washed process) or different degrees of silverskin (from honey process) are removed to reveal the green been inside. Once the coffee has been hulled, the green bean has no more protection and should be sorted, packed and stored properly as soon as possible.

The way coffee is processed will have a huge impact on the flavour and cup quality of the coffee. It is very optimistic to think that the producers have in mind the end result when choosing a process method. For many producers, when processing coffee the goal is to make the coffee as profitable as possible. Producers take into account that some methods require more time, skills or natural resources than others when deciding how to process their coffee. A more recent factor determining the chosen process is climate change. Regions that traditionally produce certain amounts of washed and natural coffee are some years confronted with very wet harvesting seasons making it impossible to naturally dry the coffee, so all coffee will be washed. Other years it’s so dry in harvesting season that there is not enough water available to wash the coffee and only naturally dried coffee can be produced.

Natural or dry processed coffee

A couple of years ago, when I was starting into the coffee world, my husband brought me some coffee from Mexico from an area that I was not so familiar with with respect to their coffee. This area is the state of Guerrero along the Pacific Coast of Mexico. The coffee was so unique, so delicious, like nothing I have tasted before. It reminded me of drinking Kalhua. We found out that this coffee was grown and roasted by a small group of farmers in Atoyac de Alvarez and what made this coffee different is that it was processed dry or natural.
The next time I heard about the natural process was when I approached the Mexican Coffee Association to find out more about these coffees to see if I can import them into Europe. They told me that the “Kalhua” taste was not so much the coffee itself, but probably due to a fermentation of the coffee. Which is true and very interesting. But unfortunately at that time natural process was almost synonym of low quality coffee and therefore hard to obtain.
Later, as I learned more and more about coffee, I tried some amazing coffees when in Ecuador: both natural and wet processed. The differences in flavour are remarkable and since the beginning of my coffee roastery I have worked with both processes. So let me elaborate on what is exactly a natural or dry process coffee and what makes it special.

Coffee, though called a bean, is not really a bean: it is a seed. Two seeds – two coffee beans- are nestled inside a coffee cherry, so basically the coffee we roast is seeds of fruits. There are multiple ways to process the fruits in order to remove the seeds: natural (dry), washed (wet), pulped natural and honey.

OLYMPUS DIGITAL CAMERA
Ripe coffee cherry (in Guatemala)
OLYMPUS DIGITAL CAMERA
Coffee seeds (coffee beans) and the skin of one cherry

The natural process is the oldest method. After picking the cherries from the coffee trees, first of all the un-ripe (green) and defective cherries should be removed by hand from the batches. Then the remaining fruits are placed in patios, or even better on tables, to dry under the sun. Hence, the entire fruit will dry. The once soft juice cherry has to remain drying for 14 to 25 days until it turns hard to the touch, it shrinks and becomes dark brown/black. The inner fruit by then has the consistency of a raisin. The drying is considered to be done when the moisture content is 12.5% or less. A higher percentage leads to rot. A resting period usually follows during which the dried cherries are stored until sold. This time, 2 or 3 months will allow the taste to mature. Finally, a hulling machine removes the dry skin from the seed.

Coffee cherries in Guatemala
Huge patio in Guatemala for drying coffee cherries (directly on the floor)

One big advantage of this process is that no water is required, so it is sustainable in the long term. This method is used where local conditions restrict access to water. Some producers do put the cherries through a quick wash to easily separate the debris from the fruit instead of picking them by hand.
However, extended periods of sunshine are necessary. Nowadays with climate changing sometimes farmers have to run to protect their drying cherries from sudden rains (unexpected outside rainy season), or gusts of wind in which the now dry cherries can easily blow away. And due to high humidity in some places the cherries are not dried outside but in “green houses” under controlled environment. Some companies even use drying machines to speed up the process. The best practice, however, remains to be the slow dry that assures that the coffee keeps its attractive qualities for longer times.

Which attractive qualities would that be? Well, this dry process accentuates the sugar profiles in the coffees. It adds fruit flavours in all coffees regardless of variety and origin. The coffee develops hints of berries, raisins or even tropical fruits. In coffees from Brazil or Ecuador it adds some hints of nuts. Another advantage of the natural process is that the farmer can play with the variables: sun exposure, moisture level, shade, and so in order to develop the flavours that he finds interesting.

Dried cheeries
Dried cherries

Worldwide there is an increasing demand for natural and other semi-washed process. The “bad name” of natural as a cheap process for low quality coffee is changing due to the attention on quality control during the process starting from the moment of picking the cherries. It is important to pick only the ripe cherries. As the fruit ripens sugars develop and create interesting flavours. Then the drying itself: selecting the best place with direct sun to dry, placing the cherries in thin layers and turning them regularly to ensure even drying and preventing moulding, fermentation or rotting taking place. A common practice is to place the cherries on the ground, though raised beds are highly recommended. Not only as a clean surface to put the cherries on but also because the wind circulation assures the cherries to dry evenly. Finally, during the drying period it is necessary to control the moisture to decide when the coffee is ready. For some producers below 12.5% is an accepted rule, some others have found better taste when drying down to 10%. Moisture is even more important once the dried fruits are collected and stored to avoid over-fermentation which would add an unpleasant flavour.

Washed beans (left) and natural beans (right) both from Cariamanga, Ecuador
Washed beans (left) and natural beans (right) both from Cariamanga, Ecuador -green
OLYMPUS DIGITAL CAMERA
Washed beans (left) and natural beans (right) both from Cariamanga, Ecuador -roasted

Due to the additional labour involved the natural process is not necessary a cheap process. But in my experience natural coffees have a wilder nature, boozy, robust, deeper character perfectly reflected in your cup of coffee. They are more challenging to roast, but the reward is definitely worth the effort. Something that is typical of natural coffees is that the beans are very unevenly coloured: from light green to yellowish or even cinnamon colour depending on the influence of the juice of the berry. This gives also a rather uneven coloured coffee after roasting that consumers have to get used to. Traditionally unevenly coloured coffee is considered the result of fast and bad roasting. However, for natural coffee it’s almost impossible to get an even roast due the variation in colour of the green beans. Therefore, the next time you see in your coffee store what looks like a unevenly roasted coffee first check what kind of coffee it is. If it’s a natural, give it a try and you may be pleasantly surprised!