Brewing Coffee Manually

Better coffee. One cup at a time.

Green Coffee Explained (In 1,652 Words or Less)

Enjoying a cup of coffee with it’s intricate flavors and comforting aromas seldom leads the average consumer down the road to wondering what all went into making such a delicious brew.

The fact of the matter is, with a misnomer like coffee bean floating around, most people don’t even know what they are drinking let alone all the delicate steps it took to process the coffee before it even arrived from origin to be roasted.

Not only is learning about what coffee is and it’s processing at origin interesting, it can shed some light on the semi-cryptic coffee lexicon and help you better understand the flavors you are tasting in your coffee and why those flavors are there in the first place.

What is coffee exactly?

Raw coffee is a small green seed that comes from a coffee tree.

The Coffea Arabica plant is a tree that grows primarily between the Tropic of Cancer and the Tropic of Capricorn. The coffee tree produces a cherry-like fruit that is most often called the coffee cherry. Inside of the fruit are two flat bottomed seeds that sit back to back in the center of the cherry. When the cherries are ripe they are harvested, the fruit is discarded, and the coffee seed is processed, dried, and bagged up for shipment.

Key factors at origin

There are a variety of things that impact the flavor and quality of a coffee at origin. Geographic and environmental factors such as region, soil, altitude, climate, and even microclimate play a pivotal role in how a coffee tastes. These factors along with varietal, help generalize coffee attributes by region.

Sweeping generalization about coffee flavors might get you in the ballpark of what to expect from a certain coffee region but the nuances of harvesting and processing create many outliers (good and bad). Expect the unexpected.

Coffee is a very labor intensive agricultural product to produce, especially well.

For great coffee, coffee cherries need to be hand picked when they are perfectly ripe. The cherries do not all ripen at the same time so the cherries are picked at several different intervals during the harvest. The opposite of selectively hand picking coffee is strip picking. In strip picking all the coffee cherries (and sometimes leaves and sticks) are harvested at once, no matter how ripe each individual cherry is. You can expect coffee that is selectively hand picked to be higher quality as well as a little more expensive.

Once the coffee cherry is picked, there are a few different ways it can be processed. It is important that the processing begins quickly to prevent rotting of the fruit which can ruin the coffee.

Processing methods vary based on available equipment and resources as well as local preferences and traditions. There are two basic mainstream processing methods: dry processing and wet processing. There is also a hybrid of sorts called pulped natural processing.

Natural Processing (Dry Processing and Unwashed)

Natural processing is the oldest and most basic way that coffee is processed. Typically you will see coffee dry processed in regions where water is limited and there is a lot of sunshine. Coffee processed via the natural method is more complex, has more body, and can be unpredictable. (See Thumbs Down post where I taste a Panama coffee that was dry processed)

After harvest the ripe coffee cherries are laid out on a patio or a raised drying bed. They are then left to ferment and dry with the seed inside. The cherries are raked and turned periodically to ensure even drying.

Drying of the coffee cherries can take up to four weeks and is something that needs to be carefully attended to. It is easy for off flavors and mold to develop during this stage. Sometimes mechanical dryers are used to dry the coffee faster and help prevent off flavor development. The dried fruit is left on the coffee bean until it is ready to be hulled.

In addition to having more body, you can also expect good natural processed coffees to be fruitier, sweeter and have a range of interesting, intense flavors. If dried on the ground, dry processed coffee can take on strong earthy flavors. (Mostly associated with Indonesian coffees).

Washed or Wet Processing

As you may have guessed by the name, wet processing coffee involves the use of water. It produces a cleaner more predictable cup than natural processed coffee.

There are a few variation on washed processing but the basic concept is the same. This process removes the pulp and a sticky substance known as the mucilage. The coffee seed is then rinsed of any remaining residue and dried on raised beds, patios, or in mechanical dryers.

In the classic washed method, the pulp is removed from the coffee cherry and the remaining mucilage and seed are left in a fermentation tank filled with water. Bacteria and natural yeasts break down the sugary mucilage, fermenting the sugars and removing it from the seed at the same time.

The amount of time the coffee spends in the fermentation tank can be anywhere from 6 hours to 4 days. It is important to be careful during this stage as over fermentation can lead to unpleasant and sour notes.

Once the fermentation is completed, the beans are washed until there is no longer any mucilage clinging to the beans. The beans are still covered with a protective coating known as parchment.

The coffee is then dried and ready for milling and sorting.

With washed coffee you can expect a mild and clean cup that has a little pop of acidity (Not that unpleasant acidity associated with coffee urns left on hot plates all day). This coffee should be approachable and easy to drink. Wet processing is the most common processing method.

Pulped Natural (The Hybrid)

There is also a hybrid processing option known as pulped natural. There seems to be a bit of a discrepancy about what exactly constitutes a pulped natural coffee. There is a similar processing method known as honey processing. Sometimes the two processes are lumped together and sometimes there is a distinction made between them.

For the purpose of this post i will blur the distinction line and explain the basic concept and process.

Traditionally, a pulped natural coffee refers to a coffee that has the pulp removed like a washed coffee but is placed on drying beds with the mucilage still attached to dry like a natural coffee. The mucilage is then removed once the coffee has dried and rested.

Variations on the pulped natural method

  • The mucilage surrounded beans are placed in a fermentation tank for a short time and then dried with the mucilage still intact (not washed).
  • A machine is used to remove some of the mucilage along with the pulp. The machine can remove a specific amount of the mucilage (60%, 40% 20% etc.). The remaining mucilage and bean are dried like naturals.
  • A machine removes all the mucilage, the bean is unwashed and dried like a natural.

Pulped natural coffees taste like you might expect, a compromise between the two methods. You can expect there to be more body and complexity than a comparable washed coffee but a cleaner more mild flavor than a natural coffee. There are of course always exceptions and other factors that provide deviations from this model.

It is also worth noting that a coffee with most or all of the mucilage removed and dried without fermentation will most likely be a bland, uninteresting coffee.

Milling, Sorting and Shipping

After a coffee is processed via one of the above methods there is normally a rest period. If the coffee was natural or pulped natural processed it is rested in the dried fruit that was left on the bean. Washed coffees just rest in their parchment.

When the coffee has been sufficiently rested it is hulled or milled. All extra materials are removed from the coffee. The coffee is then sorted, the defects are removed, and it is ready for shipment.

Other factors

Here are a few other terms and factors that may be mentioned with the coffee origin

  • Varietal- Although not always mentioned when discussing a coffee, varietal can be an important component to the profile. Roasters often have only a few words to catch a consumer’s attention so region, trade names, and processing normally take priority unless it is a trendy varietal like Gesha. There are hundreds of varietals of Coffea Arabica (most growing wild in Ethiopia) but only a handful are mainstream.
  • Peaberry- The peaberry is basically the bachelor of coffee beans. In a small percentage of coffee cherries there is only one smaller round seed instead of the pair of flat bottomed seeds, this is called a peaberry. Some people believe that the peaberry has more flavor than a normal bean because it is a concentration of the two seeds into one. Regardless if this is true or not, peaberries are separated during the sorting process and sold separately. Peaberry is normally something noted on a roaster’s coffee description.
  • Aged Coffee- Although not very common, some people enjoy coffee that has been aged. The aging process consists of beans sitting in humid warehouses in burlap sacks. If the aging is done correctly, a great depth of flavor and uniqueness can be added. Some coffee can be aged 5 plus years. I know of one roaster in Chicago, Dark Matter, that ages their own coffee in bourbon and beer barrels.

I hope this starts to shed a little light on the complex world of growing and processing coffee. I have never been to a coffee farm or washing station so my knowledge is purely research based.

If you have any questions, something to add, or would like to discuss some of these topics further, please feel free to email or leave a comment below. At the same time if I have oversimplified, overcomplicated, or gotten something incorrect please let me know. Thanks!

1 Comment

  1. I appreciate your writings about coffee. The quality of my life has improved dramatically with the knowledge obtained from your blog. Thank you. Brian

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