"PROCESS": What does it all mean...?
"Natural", "Washed", "Honey" - you've seen it on the bags but want to know what it means and how it affects your cup. Read on.
First, we’ll have a look at the anatomy of a coffee cherry. And then we’ll discuss the various ways in which coffee cherries can be transformed into nicely roasted delicious coffee.
The Anatomy of a Coffee Cherry A coffee cherry has, roughly speaking, five layers
The five layers are:
Skin / Pulp: On the outside, the two coffee seeds are covered by a cherry-like skin. With the exception of dried-in-the-fruit or Natural Process coffee, this outer layer is removed within a few hours of harvest. In an edible cherry we might call this skin the “flesh”. In coffee, the skin is mostly considered a by-product (some make tea out of it). That’s why it’s called “pulp” and the machine to remove it is called a depulper.
Mucilage: Beyond the skin lies the mucilage, a sticky, gluey substance surrounding each of the two seeds. Since it is so sticky and sugary, it is sometimes called Honey. (Mucilage is found in most fruit. It’s not unique to coffee: http://en.wikipedia.org/wiki/Mucilage)
Parchment: After the mucilage, a layer of cellulose protects each of the coffee seeds. When dried, this layer looks and feels like parchment paper, hence the name.
Silver skin / Chaff: Further inside, an even thinner layer coats the seed. This layer is called the silver skin because of its somewhat silverish sheen. This layer comes off during roasting. If you ever notice flakes in ground coffee, that is usually bits of silver skin or chaff that didn’t separate from the beans during the roast process.
Seed / Coffee Bean: As you’ve already discovered, basically the coffee bean is one of the two seeds from inside the coffee cherry (Peaberries are an anomaly in which only one small, round seed formed inside the cherry. Usually, about five percent of all coffee is graded as a peaberry.) It is dried and infertile by time we receive it, ready to roast.
The Three Principal Processing Methods in Coffee We know of three principal categories of processing methods. These three processes differ in the number of layers that are removed before drying. Here is the short list:
Natural or Dried in the Fruit Process – no layers are removed.
Honey Process – skin and pulp are removed, but some or all of the mucilage (Honey) remains.
Washed Process – skin, pulp, and mucilage are removed using water and fermentation. Also called Fully Washed. This is the conventional form of Arabica coffee processing used in most parts of the world. It is possible to skip the fermentation step by using a high-tech pressure washing machine to remove the skin, pulp and some or all of the mucilage. This process is called Pulped Natural.
In terms of how many layers of the fruit are removed, and how much water is used, the Honey Process is about mid-way between the Natural (Dry) and Washed (Wet) Processes.
Natural or Dried-in-the-Fruit This is the easiest method to explain: the cherry gets picked off the bush and dried more or less without further ado. This is the oldest method, and is still used in Ethiopia and Brazil and sometimes in other coffee growing areas, especially when there is no water available. Drying can take up to four weeks, and it is very tricky to ensure that no moldy or off flavors get into the beans. It only works well in very dry climates or when supplemented by mechanical drying (basically running hot air through the beans to dry them faster and in a more controlled way.)
Drying coffee in the fruit keeps many of the fruit flavors in the beans. You’ll find that coffees processed in this way are often very fruit forward tasting and brighter than other coffees. The pulp is removed mechanically after the cherries are dried (“Dry Milling”).
Washed In this method, the skin of the coffee cherry is removed mechanically using a specialized machine, called a depulper. Then the beans are put into fermentation tanks until the mucilage is no longer sticky. The sugar in the mucilage gets broken down during the fermentation process. Depending on the fermentation method, this takes anywhere from 12 hours to six days (some farmers ferment the coffee using several rinse cycles, this is called the Kenyan method and takes several days). Determining when to end the fermentation is very important – over-fermented coffee will taste sour! Once the stickiness is used up, the remnants of the mucilage are washed off using copious amounts of water. (The huge amount of water used to wash off the mucilage is one of the worst environmental impacts of coffee production, but there are some newer innovations that decrease, recycle and filter the water used in this method.) This method was developed in the 19th century and is also called “wet processing”.
The controlled fermentation of the mucilage imparts a certain amount of acidity into the coffee which persists into the cup. However, by washing the beans right after fermentation, much of the fruit flavor and acidity is removed. What remains are the more subtle flavors of coffee alongside a good bit of acidity.
Pulped Natural Pulped Natural is a common processing method in Brazil. Pulped Natural is similar to the Washed process except that the mucilage is removed using a pressure washing apparatus, skipping the fermentation process altogether. A couple of companies in Brazil and Colombia have had this method patented and remain the market leaders with a quasi-monopoly on this pressure washing “Robot”. The method uses much less water than the Washed Process, so it is sometimes called Semi-Dry. Since there is no fermentation, there is little risk of over/ under fermentation, thus increasing overall consistency. Unfortunately, without any fermentation, the flavor tends to be consistent but bland. For this reason, farmers do not use this method on super-premium coffee varieties, and we rarely buy coffee that is processed in this way.
Honey Process Honey process is currently all the rage in Costa Rica and it has started to spread to all the other Central American countries. Remember that the mucilage of the coffee cherry is sticky and slimy, so it is sometimes called “honey”. During the Honey Process, coffee is dried with some or all of the mucilage remaining on the parchment encasing the seed. Coffee cherries are picked, sorted, depulped, and then moved to drying patios or beds for various periods of time.
Because there is a little bit of fermentation happening in the short amount of time it takes for the mucilage to dry, coffees processed in this way feature a little more acidity than Pulped Naturals (Pressure-Washed) coffees, but significantly less acidity than Washed or Natural/Dried-in-the-Fruit coffees.
The Honey Color Spectrum Recently, some Costa Rican farmers started assigning a color attribute to their Honey processed coffee: Yellow, Red, or Black. This indicates the amount of light the coffee gets exposed to during drying.
Most coffee producers want to produce the most profitable, and therefore the best-tasting, coffee they can, but they’re limited by the environment. Coffee, more so than most foodstuff, has a very close bond to its surrounding environment.
Producers will often wait to see how much rain has fallen before decide whether to produce washed, honey, or natural coffee. If it’s rained a lot, it’s harder to produce good natural process because coffee cherries can start splitting. If it hasn’t rained, conditions are great for honey process or natural process because no sugars will get washed away.
An increasing number of farmers are now willing, where environmental and climatic factors allow, to try other processing techniques. For example, in Nicaragua, Guatemala, and Rwanda, some farms and cooperatives are turning towards the natural and honey processes. By doing this, they can create new, unusual flavour profiles that add value to their crop.
This goes beyond simply choosing a processing method: some producers are experimenting with the absence of oxygen for fermentation, while others are looking at catalysts to speed up fermentation. Some are also looking closer at their environmental impact, and trying to process coffees while cutting down on their use of water. New machinery and knowledge-sharing are also helping to create more unique cup profiles.
There’s a demand for experimental processing methods; coffees produced with alternative processing methods sometimes sell out even before they’re picked. This means we can expect to see even more creative innovations in processing in the future.
Coffee processing rarely makes it into the industry headlines or coffee shop discussions, but it’s an integral part of crafting the flavour and character of your cup of coffee. So next time you pick up a honey processed Costa Rican or a natural processed Nicaraguan, you’ll know what to look forward to.
Credit: Seattle Coffee Works