After devoting the last few articles entirely to the tasks on and around the farm, in today's article we want to slowly but surely turn our attention to processing after the harvest. In the article about the coffee producer we already touched on the individual steps that coffee goes through after the harvest.
But in this article we will cover what is probably the most important step in the processing of coffee when it comes to the taste in the cup profile. It is the preparation of green coffee. That is, the process by which the coffee cherry is processed into green coffee. In the coffee world, this process is generally referred to as green coffee preparation, or also as processing. The process of preparing green coffee is extremely complex and, above all, there are numerous differences that have different effects on the coffee, which you can also feel in your cup. Elias Fischbacher from the Wildkaffee Rösterei wishes you lots of fun and a good insight into the world of coffee processing.
Green coffee processing - General
But what exactly is behind the term green coffee processing and how does this process work? In general, processing is the first processing step that is carried out after the harvest. It is the process in which the pulp, the pulp and the parchment skin of the coffee cherry are separated from the stone.
The core of the coffee cherry is then the actual green coffee. When it comes to processing or preparing green coffee, there are numerous different variants that work with different mechanisms. In the course of the Third Coffee Wave, there has been intensive tinkering with the processing of green coffee, because the different processing methods also bring different flavors to your coffee, which can be specifically influenced by the coffee producer. You can find out in detail which variants of processing green coffee there are in the following sections.
Processing green coffee - Classic methods
As in almost every industry, there are variants of green coffee processing that were used hundreds of years ago. We refer to these as classics. To this day, these classic methods of processing green coffee are the ones that are most commonly used. Especially in developing countries where coffee is cultivated, there is often a lack of money or information about new processing methods.
Furthermore, certain methods of processing green coffee require modern machines that smaller farmers in particular cannot afford. However, it is definitely not correct to consider the classic processing methods as inferior. The classic processing of green coffee ensures a clear, nuanced coffee taste that highlights the typical notes from the coffees in the countries of origin. But there are also differences between the classic methods of processing green coffee. And these are the classic processing methods:
Processing green coffee - washed
The washed processing of green coffee, also known as washed processing, is probably the most authentic way to reproduce the taste of coffee. The cherries are first emptied into a large basin. The cherries floating on top are sorted out - the others are sent through the pulper, which separates the actual green coffee bean, i.e. the kernel, from the pulp of the coffee cherry. All that remains on the green coffee bean is the silver skin and the mucilage. To remove these, the beans are "lightly" fermented again in the same basin.
This process also affects the taste of the bean, but the main purpose of this process is to remove the mucilage. After this process, the green coffee bean is washed again and then dried in the sun. The washed processing of green coffee preserves the original taste of the country's coffee. Washed processing is used particularly in the high altitudes of South America, but washed processing is also used in parts of Africa.
Green coffee processing - semi-dry / semi-washed / honey processed
A mixture of washed and dry processing is the semi-dry processing of green coffee. Similar to the washed processing, the coffee cherries are first washed and peeled or pulped. However, the remaining silver skins and mucilage are not removed by fermentation and another washing process, but dried in the sun as in the dry processing of green coffee.
However, the beans must be carefully monitored and turned regularly during drying, otherwise an undesirable fermentation process could occur or, even more seriously, the beans could rot and become completely unusable. The mucilage and the silver skins together form a slimy, sticky layer that is reminiscent of honey. This is why this processing of green coffee is also called honey processing. The sweetness of this mucilage is actually reflected in the cup profile.
Processing green coffee - dry / natural
The most original processing method is clearly the dry processing of green coffee. This method is also known as natural processing and is used particularly in dry, hot regions where the humidity is low. The cherries are usually placed on so-called African Beds or Drying Beds. These drying beds are slightly raised and have an air-permeable net on which the cherries are placed to dry.
The surface allows the cherries to be ventilated from all sides and therefore dry more quickly. On smaller farms, the cherries are spread out on a larger paved area and dried in the sun. Tarpaulins or roofs are often put up to protect the cherries from precipitation. To prevent fermentation or even mold, the cherries must be constantly turned and inspected during the drying process. The drying process is finished after about 2 to 5 weeks. The color has changed from a strong red to a dark brown. In terms of taste, naturally processed coffees have a finely sweet, yet clear taste that brings out the nuances of the country's typical flavors.
Green coffee processing - experimental methods
In addition to the classic preparation methods, there are also new methods that have become established and developed further in the wake of the third coffee wave. The main focus of these methods is on playing with fermentation. The targeted fermentation of the cherries ensures exceptional notes in the cup profile. These notes are strongly fruity and can be described as quite crazy.
But fans of specialty coffee in particular love this unique taste. No wonder, because once you get used to the tangy, fruity variety of flavors, you hardly want to enjoy any other coffee. In the following sections, you will find out exactly how these complex flavors are created and which variants there are.
Green coffee processing anaerobic
Anaerobic processing is a rather complex method for separating the pulp from the bean. But the complex processing ultimately results in a complex taste experience, but more on that later. Anaerobic generally means that the coffee is processed without oxygen. Conversely, this means that the pulp is washed off the cherry pit and placed in the so-called fermentation tanks together with the pits.
The tanks are then sealed so that they are oxygen-tight, which means that fermentation takes place without any oxygen. The CO2 produced during the fermentation process is released through a special valve on the tanks. There is also a method in which the cherries are put into the tanks whole. The variant depends entirely on the coffee producer's taste goals. Fermentation usually takes around 72 hours, after which the green coffee beans undergo a long drying phase. Anaerobic processing gives the coffee a completely new taste experience. The very complex process gives the cup profile a fruity sweetness that can definitely be described as a real special feature.
Green Coffee Processing Aerobics
The aerobic processing of green coffee, however, works in the opposite way to the anaerobic variant. The cherries are fermented in so-called open-air tanks. The tanks provide an oxygen-rich environment. Another difference is the process after the harvest. In aerobic processing, the cherries are put into the tanks dry, while in the anaerobic variant the cherries are washed beforehand.
The ripe cherries are fermented in the tanks at an average temperature of 24 degrees for around 86 hours. This is followed by a long drying process that lasts around 28 days. During the fermentation process, microorganisms are formed that influence the taste of the coffee. The long fermentation period and the long drying phase give the coffee an exciting, floral taste with fine fruity accents in the cup profile.
Processing green coffee - Mosto
Another rather crazy processing method is the Mosto processing of green coffee, which is more commonly known in the coffee world as Candy Natural. The Mosto processing also works according to the fermentation principle, but the cherries are not fermented in large tanks and with water or even naturally, but rather in special GrainPro bags.
In these GrainPro bags, the ripe fruit is mixed with a so-called "mosto", the juice that is produced during the anaerobic processing of green coffee in the tanks. The cherries then ferment in the bags for 3-4 days before being laid out on African Beds to dry. The coffee must be turned particularly frequently so that it can dry slowly and evenly. The coffee impresses with its fruity sweetness that is rounded off with a high acid content and a complex body.
Processing green coffee - Microorganism
When processing green coffee, especially when using experimental methods, microorganisms are created, primarily through fermentation, which bring the fruity-sweet taste to the cup profile. But what happens when you let additional microorganisms work in the fermentation? Simply put, it's a complex coffee experience.
Especially today, the production of one's own microorganisms on the plantations is a significant part when it comes to cultivation according to the principles of organic farming. The microorganisms are usually obtained from the remains of the processing of green coffee and can be used in many ways. Be it as a pesticide, as fertilizer or for processing. The use of microorganisms in processing requires a lot of experience. They must be used in a targeted manner so that the coffee flavor can develop in a nuanced and clear way.
Green coffee processing - infusion
We are slowly getting to the most experimental processing methods. Infusion processing can be described as a little crazier. Like the other methods, this processing also works with fermentation. The difference is that not only is the core fermented in its own pulp, but any flavoring additives are also fermented in the large steel tank or container. This can be an orange infusion, a coconut infusion or something similar. There are no limits to creativity here, although the infusion must always be of natural origin. Artificial flavors or similar are not desired and are permitted. The end result promises an extraordinary cup profile thanks to the flavoring additives.
Green coffee processing - Carbonic Maceration
Another unusual method for separating the pulp from the cherry stone is the carbonic maceration method. This method was inspired by winemaking and produces exceptional notes in the cup profile. With this method, the cherries are first sorted and then placed in a large stainless steel tank that is sealed to prevent oxygen from entering.
Carbon dioxide is pumped into the tank and since oxygen is lighter than CO2, it is pushed out through a valve on the top of the tank. The different pectins and sugars that are created during fermentation are processed by the natural microorganisms. The result: outstanding cup profiles that produce a taste of sweet fruit.
The difference between classical & experimental processing
As you have already read, the classic processing methods differ significantly from the experimental variants. It is also clear that the different variants are aimed at different target groups. While the classic processing methods of green coffee reproduce the country's typical coffee taste clearly and nuanced, the experimental variants impress with their exceptionally fruity and sweet accents.
The crazier flavor accents enabled the farmers and producers to sell their coffee to other target customers and thus convince other coffee dealers of their coffee. The processing of green coffee is constantly evolving in this respect, which means that new, interesting notes keep emerging. The classic processing methods, on the other hand, have been established for years and form the basis of all new processing methods. In general, it can be said that the classic processing methods aim for the typical taste of the countries of origin, while the experimental variants target unusual notes. #staywild
