By Jonathan Parent

On the Bag - Grain Processing Methods Explained

1 of 4 - La Société des Cafés brings you the first in a series of articles designed to better understand the information roasters provide on their bags of coffee. To kick off this series of articles, we'll look at the different bean processing methods that can change both the composition of the green bean and the profile of the coffee in your cup. We approached Simon Fabi, owner of Cantook, in Quebec, as well as Ann Hnatyshyn of House of Funk, a Vancouver microbrewery and roaster, to get their thoughts on post-harvest processes, from the most popular to recent innovations.


It should be noted that once the fruits of the coffee trees are harvested, coffee growers can use a variety of methods to process the beans. The main objective at this stage is to remove the outer layers of the coffee cherry (parchment, mucilage and pulp) to ultimately only retain the green beans that form the core. Parameters such as time, equipment and available natural resources will influence the choice of the method recommended by farmers. More often than not, roasters offernatural coffees,washed andhoneys, which are the most common grain processing methods. However, we have seen the emergence of more experimental processes for a few years now: fermentations in the environment.anaerobic(limited in oxygen),coffees aged in barrels and others inoculated with nutritional yeasts. While these innovations are used in particular by producing farms to stand out in the international coffee market, they also allow the development of new flavors (fragrance and taste), thus giving coffee a rather unique profile. On the bags, these intriguing formulations (for example: 100% honey, carbonic maceration,diamond honey) become essential indicators in order, on the one hand, to understand the approach of producing farms and on the other hand, to discover our preferences as coffee lovers.

Let's peel natural, washed and honey treatments

Natural coffees1

Considered to be the oldest method, natural (or dry) treatment involves, after all, little intervention on the part of the farmers. Since this process takes place without water, it is common to see natural coffees from regions where accessibility to this resource is restricted (parts of Ethiopia and Brazil for example). After harvest, whole coffee cherries are laid out on sun-drying beds (brick patios, raised beds). Coffee cherries can take several weeks to dry. During this period, farmers should regularly turn the fruit so that it can dry evenly and to avoid unintended effects (mold, decay or unwanted fermentation) being stimulated. Once the coffee cherries are completely dry, the outer layers are mechanically removed to keep only the coffee beans.

Profile - Natural coffees offer, regardless of the variety and the terroir, a more fruity profile (strawberries, blackberries, tropical fruits, etc.), wild notes and a pronounced fermented side.

See our coffees from natural products


Washed coffees

The washed (or wet) treatment of the coffee beans is generally available in three stages. The coffee cherries are first pulped using a machine called, logically, the pulper. Then, the remaining parts of the fruit (the grains wrapped in mucilage) are put into fermentation tanks (with or without water). The fermentation that takes place there allows the mucilage to break away from the coffee beans. Fermentation time varies depending on various factors including altitude and ambient temperature. However, we can say that it usually takes 12 to 72 hours. Finally, the seeds are rinsed to remove the last traces of the layers of the fruit and are dried in the sun. Since a significant amount of water is used in the process to remove the outer layers of the cherry, there are also environmental concerns.

Profile - The washing process gives coffee an often delicate profile with more pronounced acidity. Washed coffees are appreciated for their clarity as well as their complexity.

See our coffees from the washed process


Honey coffees

More common in Central America (Costa Rica and El Salvador), the honey process requires machine-pulping the coffee cherries while leaving a certain percentage of mucilage on the beans. This percentage will determine whether it is white honey (the lower amount), yellow, golden, red or black (the higher amount). The grains are then spread out in drying areas. The more mucilage left on the beans, the longer the drying and fermentation time. This period allows the sugar in the mucilage to be absorbed into the grains.

Profile - Being a hybrid between dry and wet processing, the honey process (honey in Spanish means mucilage) results in a cup with more body. We find there the sweetness of natural coffees and the acidity of washed coffees.vés.

See our coffees from the honey process


Innovations and other experiments

Anaerobic method

It was about five years ago, during a trip to Costa Rica (a country he is particularly fond of), that Simon Fabi,Cantook owner, tasted his first anaerobic coffees. The producing farms were then at the experimental stage. Now, there are several roasters that offer it. In fact, anaerobic coffees are made from cherries that are usually pulped and then placed in airtight tanks, without oxygen. These are fitted with valves to release the gases produced during fermentation, which generally lasts between 12 and 20 hours. Some coffees can ferment for up to 48 hours. This oxygen-limited environment only allows a part of the bacterial flora (the one capable of surviving in such conditions) to participate in the fermentation and to shape the final profile of the coffee. The pressure in the tank allows the amino acids produced to migrate into the parchment (the cartilaginous part enveloping the beans) and give the coffees more frank and explosive notes. Once fermentation is complete, the coffee beans are then dried in drying areas.

See our coffees from the anaerobic process


Carbonic maceration

Carbonic maceration has many points in common with anaerobic coffee processing, since both methods involve fermentation in an oxygen-limited environment. What distinguishes coffees resulting from carbonic maceration from anaerobic ones, however, is that the cherries are not pulped, but placed intact in the sealed tanks. Since the fruits are put whole, the fermentation process can last several days, and even several weeks. Again, the pressure in the tank releases the sugars and pectin substances which will be macerated by the bacterial flora present. While the coffee cherries at the bottom of the tank compress under the effects of gravity, those above will give rise to a slower fermentation taking place directly on the skin of the fruit. We owe carbonic maceration to the wine industry, more specifically to the practices of the Beaujolais region in France. Both wines and coffees produced by such a method are known to be juicy and fruity.

Example of coffee in carbonic maceration

Maceration in rum barrels

Of these new methods, some say that the tasting notes are less linked to the variety of cherries and the terroir, but much more to the effects of the process. Simon Fabi from Cantook also points out that coffees from such fermentations often have a marked winey side. These coffees smell and taste of a pile of pulp fermenting in the sun. They smell and taste the producing countries, he tells us. In himself, Simon Fabi sees coffees derived from such processes as unique and sometimes unsettling taste experiences that he wishes to share with coffee lovers here. Some coffee producers even go so far as to add other elements (eg tropical fruits, cinnamon, molasses) during fermentation. This practice of anaerobic impregnation, however, is not a consensus. Some see it as a way of altering the very natural taste of coffee beans, and others are enthusiastic about the unexpected flavors that can arise.r.

For Ann Hnatyshyn fromHouse of funk, these experiments are particularly stimulating. She says she was speechless after tasting, during a cupping session, a fermented coffee with dried mandarins (it was just THAT good). It's about coffee « Mandarum » produced by the Finca La Fortuna farm in Colombia. The ripe cherries undergo a 48 hour fermentation in an anaerobic environment with the dried tangerines. After that, the coffee covered with tangerines is brought to raised beds to dry to a humidity level of 10.5%. The completely dry coffee beans are finally aged in rum barrels for 15 days. The House of Funk team seeks to roast coffee beans whose profile tends to stand out from industry standards. His practice leads him to offer several coffees aged in barrels having previously contained different kinds of alcohol. For example, House of Funk bought Kentucky bourbon casks and white wine casks from Vancouver Island vineyards and put green beans in them for up to 3 months. Once in the barrels, the green beans soak up the alcoholic flavors soaked into the walls, which in the cup offer hybrid coffees with the taste characteristics of the chosen alcohols.

Other fermentation processes also stand out:

Diamond honey : The coffee beans, wrapped in their mucilage, are piled up in a pyramid shape out of direct sunlight, which slows down fermentation. The stacks are turned to prevent only the cherries in the middle from fermenting more.

Inoculated with nutritional yeasts : In order to control the parameters of fermentation, coffee producers will introduce a bacterial flora developed in the laboratory rather than using that which is found naturally on coffee cherries and in the environment nearby .

Even if they have been proven successful, these new bean fermentation processes for coffee producers are financially risky. The purchase of equipment, the considerable duration of the process and the added manipulations increase production costs as well as the possibility of encountering certain obstacles (for example: incursion of an unwanted yeast, erroneous manipulations, surfermentation). In return, these innovative treatments allow producing farms to obtain better prices for their beans from interested roasters and consequently, to have a higher income.


A consensus on the nomenclature?

The terms we have used to categorize bean processing methods may, depending on the coffee industry, be confusing because of their imprecision, but especially since practices vary from region to region. As an example, we explained earlier how honey coffees are classified by color according to the amount of mucilage left during drying. However, some coffee producers will leave all of the mucilage on the coffee beans and it is the time before turning the cherries during drying that will determine the associated color (black honey being the one that fermented the longest before dying. 'be returned and white honey, the one having been returned more quickly)2. thediagram designed by Evan Gilman and Chris Kornmanfor the Daily Coffee News makes it possible to clearly visualize the extent of possible variations in the coffee industry, both for so-called traditional methods and more widespread than the new fermentation processes.3 

All in all, each of the common and innovative grain processing methods involves some degree of fermentation. We must see in the coffee bean a living entity that interacts with its environment and reacts to it.t.4 It is this interaction that coffee producers will seek to control and shape in order to produce delicious coffees with sometimes surprising notes. The process mentions on the coffee bags thus demonstrate the know-how and inventiveness of coffee producers. To showcase the results of this work, roasters will often roast the beans lighter and faster to preserve the acidity and delicate flavors of the coffee, notes Ann Hnatyshyn. This is why these coffees generally lend themselves best to drinking as a filter, which enhances and appreciates the subtleties of the bean.


Text by Chloé Pouliot

Sources consulted

  • Thanks to Simon Fabi (Cantook) and Ann Hnatyshyn (House of Funk) for your interest, availability and enriching exchanges.
  • Chris Kornman, A Guide to Carbonic Maceration and Anaerobic Fermentation in Coffee, Daily Coffee News.s.
  • Chris Kornman, Coffee Processing Styles and Terminology (Plus Flowchart), Daily Coffee News.s.
  • James Hoffman, The World Atlas of Coffee.
  • Jori Korhonen, Coffee Processing Methods - Drying, Washing or Honey, Barista Institute.te.
  • Simon Fabi, # 010 Journeys to the Origin, Café Normal.l.
  • Sophie Jiyuan Zhang and Florac de Bruyan, The Effect of Fermentation, Specialty Coffee Association.n.



 1.Jori Korhonen, Coffee Processing Methods - Drying, Washing or Honey,», Barista Institute.
2. Simon Fabi on the Café Normal podcast, # 010 Travel to Origin.».
3.Chris Kornman, Coffee Processing Styles and Terminology (Plus Flowchart), Daily Coffee News.s.
4. Sophie Jiyuan Zhang and Florac de Bruyan, The Effect of Fermentation, Specialty Coffee Association.n.