A Beginner's Guide to Coffee
In Parts One, Two, and Three of this Coffee 101 series, we learned what coffee is, where it comes from, and how it is grown. We now turn our attention to the most labor-intensive phase of coffee's journey - that of production.
Previously: Part One - What Is Coffee?
Previously: Part Two - Where Does Coffee Come From?
Previously: Part Three - How Is Coffee Grown?
Unlike orange juice, which can be squeezed from ripe oranges, or an apple, which can be picked from a tree and enjoyed immediately, coffee requires extensive and laborious effort before taking its final form as a magical beverage enjoyed by millions.
Coffee cherries, as the fruit of the coffee plant is commonly known, must first be picked and processed before they can be roasted. Once the ripe fruit is harvested from the plant, these cherries undergo a series of dramatic transformations to become the beloved coffee bean.
To transition from fruit to bean, coffee must be harvested and processed. Methods and techniques vary depending on the type and growing region. How coffee is processed impacts its flavor profile as much as the variety and what part of the world it comes from.
As one of the world's most valuable agricultural products and heavily traded global commodity, coffee is not only one of the most popular beverages on the planet, it is in one way or another, connected to the lives and livelihoods of hundreds of countless people. Here's how coffee is produced.
How Do They Produce Coffee?
We all know coffee as that profoundly flavorful beverage that satisfies in a way like no other. So it is easy to forget that the coffee beans we cherish started their journey thousands of miles away in distant lands scattered throughout the so-called coffee belt.
To recap what we've learned so far in this series:
In Part One, we learned the basics of coffee by focusing on the plant itself
In Part Two, we explored where coffee comes from including its origins
In Part Three, we studied the conditions that coffee plants need to grow and thrive
This brings us to this fourth installment where we will go into how coffee cherries are processed into coffee beans. To fully appreciate the different stages of coffee production, it is first necessary to understand the basic anatomy of the coffee cherry.
The Anatomy of the Coffee Cherry
As we learned in Part One - What Is Coffee, the beloved coffee bean is actually a seed contained within the fruit of the coffee plant. There are normally two seeds nestled inside each coffee cherry and their general appearance is characterized by these traits:
They are flat on one side and rounded on the other
A long groove runs lengthwise on the flat side of the seed
They are typically oval-shaped, although some varieties have a rounder appearance
Surrounding the coffee seeds are various layers of material that must be removed through the different stages of processing (more on these methods later).
Outer Skin (Exocarp)
The outermost layer of a coffee cherry is the tough outer skin or peel (also known as the exocarp). The outer skin of coffee cherries starts out olive green in color and transforms into various shades of red as the fruit matures and becomes ripe for picking.
Pulp (Mesocarp)
This is the meaty flesh lying just beneath the outer skin and surrounding the seeds. The pulp, also known as the mesocarp or mucilage, is the thickest layer of the coffee cherry, and the various coffee processing methods aim to remove this along with the exocarp.
Just inside the pulp is another layer with a slimy consistency known as the parenchyma. Along with the pulp, the parenchyma protects the seeds during their development.
Parchment (Endocarp)
Also known as the endocarp, parchment is a layer of paper-like material completely enveloping the seeds inside the coffee cherry. The main purpose of parchment is to provide a protective barrier around coffee seeds throughout their growth cycle.
Parchment is removed from coffee seeds through a process known as hulling. Some producers around the world store coffee beans with the parchment layer intact to preserve delicate flavors and characteristics between the final stages of processing.
Silver Skin
Coffee seeds are surrounded by a thin, membrane-like layer known as the silver skin. Most of the silver skin is removed when coffee beans are processed (the polishing phase) but it is not uncommon for remnants to remain attached to green coffee when it is exported.
When green beans are roasted, any remaining silver skin falls off and ends up in the chaff collector of the roasting system.
Seed
Through the various stages of processing, the seeds of coffee cherries are transformed into coffee beans. The fundamental goal of processing methods employed by the world's coffee producers is to extract the seeds from coffee cherries and remove as much of the surrounding layers as possible.
Harvesting Coffee Cherries
Coffee beans as we know them are the seeds of fruit growing in dense clusters on the branches of coffee plants. From initial planting, most coffee plants take three to four years to mature enough to bear harvestable fruit. Certain varieties can take even longer.
When coffee cherries reach ripeness, they transform from various shades of green to their familiar deep red color.
Before coffee cherries can be processed and their seeds removed, they must be picked. Separating coffee cherries from the plant can be a laborious and costly process. Depending on the region or local practices, harvesting coffee cherries can be done manually or mechanically. Here's a look at both methods.
Manual Coffee Cherry Harvesting
The majority of coffee farms around the world employ manual labor to pick ripe coffee cherries from the branches of coffee plants. Under this method, ripe fruit is hand-picked by laborers who move methodically from plant to plant, filling their baskets with coffee cherries. While tedious, this method greatly reduces the number of unripe or overripe fruit that are picked.
It is said that an experienced picker can harvest anywhere from 100 to 200 pounds of ripe coffee cherries per day.
For each pound of coffee beans, roughly five pounds of fruit must be harvested. Put another way, 100 pounds of ripe coffee cherries, a full day's worth of picked fruit for many laborers, will yield approximately 20 pounds of coffee beans.
Not only is manual picking very laborious, but it is a cost that is often passed along the supply chain by producers who must maintain pickers on their payroll.
Mechanical Coffee Cherry Harvesting
The alternative to manual picking by hand is mechanized harvesting utilizing automated equipment. There are two main categories of mechanical harvesting equipment:
Handheld picking equipment typically consists of mechanical agitators mounted on the ends of poles which shake cherries loose from branches.
For larger-scale harvesting, mechanized shakers and strippers, many of which can be driven around a plantation, can quickly remove high volumes of cherries from coffee plants. They require flat terrain to operate and do not discern ripe fruit from unripe. Operators must often use post-harvest sorters and similar equipment to maintain quality control.
While mechanical coffee cherry harvesting is faster and more cost-efficient than manual picking, it can also result in poorer quality by including fruit that is unripe or overripe.
Common Coffee Processing Methods Around the World
The primary objective of coffee processing is to extract the seeds from coffee cherries and remove as much of the surrounding fruit material as possible.
A secondary purpose of coffee processing is to impart certain characteristics into the coffee beans that will yield desired flavor attributes when brewed.
When it comes to coffee methods used around the world, there are two basic categories: natural and washed. Let's take a closer look at each.
Dry (Natural) Processing
Dry processing, commonly known as natural processing, is the most basic and oldest method of processing coffee cherries into green coffee beans.
Dry processing is not only the most cost-effective technique, but in areas where water is a scarce resource, it may be the only viable option to process coffee beans.
Here are the basics of how dry processing works:
Once ripe coffee cherries have been picked, they are laid out evenly on large patios to dry out in the sun (this stage typically takes two to four weeks)
As the cherries continue to lay out in the sun, they are periodically raked to ensure even drying and prevent rot and mildew formation
This drying process causes the outer skin and pulp to harden and contract as they dry out
The moisture content of the cherries steadily drops as they continue to dry and once the level reaches 11% to 12%, the dried cherries are gathered for the next stage of processing
Once coffee cherries are thoroughly sun-dried, they are taken to mills where the outer skin, pulp, and parchment layers are removed through a process known as hulling
Naturally processed coffee beans are known to have a distinct character largely due to the prolonged contact between the inner seeds and the slow-drying pulp and outer peel surrounding them.
Dry processing is prevalent in Ethiopia, the birthplace of coffee, and Brazil, the world's largest producer of coffee.
Wet (Washed) Processing
The wet, or washed, processing method is more widely used to process coffee beans than the dry method. As the name suggests, water usage figures prominently during the processing of picked cherries and the removal of the outer layers of the fruit.
Washed coffees are touted by many to produce a cleaner cup with more complex flavor notes and sublime characteristics.
These are the basic steps of wet processing:
Harvested coffee cherries are loaded into mechanical pulping machines to remove most of the fleshy outer layers.
The seeds are left with remnants of pulp attached to them along with the slimy parenchyma and parchment.
The partially processed seeds are transferred to large vats or tanks where they are left to ferment for 48 to 72 hours. It is during this stage that naturally occurring enzymes and microbes break down the sticky mucilage.
All remaining pulp residue is washed away from the seeds by rinsing them with water in long channels.
Manual agitation of the water is sometimes needed to shake loose bits of pulp from the seeds.
It is common for this process to be repeated to thoroughly wash off the outer layers of the cherries.
Parchment coffee, as the washed seeds are now referred to, must be dried before it can undergo final processing. Typically, the drying process is performed by laying the parchment coffee on large platforms under sunlight for approximately one week. The goal is to achieve a moisture content level of 11%-12%.
Once sufficiently dried, parchment coffee must be hulled before it can be sorted, graded, and bagged for export.
Wet processing is the preferred method in Colombia, Central America (namely, Costa Rica and Guatemala), and portions of Africa, including most notably, Kenya and Tanzania.
Other Processing Methods
The dry (natural) and wet (washed) processing methods are by far the two most common production protocols for coffee around the world today. But there are other processing techniques and some are employed by prominent growing regions renowned for the quality and character of their coffees. The choice of which processing method to utilize often depends on:
What resources (e.g., water, land, equipment, labor) are locally available
Regional coffee culture and traditional practices
Desired attributes in the final processed coffee
The most notable among specialized or regionalized processing methods are (1) semi-washed and (2) semi-dry techniques. They are often mistaken for one another and some of the differences between them are subtle and can be confusing. Here's a closer look at both.
Semi-Washed Processing
The term semi-washed processing simply means that significantly less water is used to process picked cherries compared to fully-washed coffee. Because semi-washed beans require a fraction of the water (up to 90% less) used for traditional wet processing, this method is often employed in areas where water is a scarce or expensive resource.
Semi-washed coffees fall into two categories:
Pulped Natural Process
Pulped natural coffees undergo a pulping stage with minimal water usage that removes most of the outer skin and pulp surrounding the seed. At this point, the seeds have visible flesh remaining on them and they are laid out to dry in a manner that is similar to dry-processed coffees.
The primary difference between pulped natural beans and those that are dry processed is that the latter is done with the entire cherry intact.
Honey Process
A coffee category that has been gaining popularity in recent years is honey-processed beans. Like the pulped natural method, the honey process involves an initial pulping stage that removes the outer skin and flesh from ripe coffee cherries.
The main difference is that honey-processed seeds have significantly more pulp removed from them than pulped natural so only the slimy parenchyma layer remains on the parchment. Honey processing gets its name from the unique appearance it imparts on the coffee beans as they go through its various stages.
As it dries, the residue remaining on the partially pulped beans takes on a sticky quality and the color transforms into darker hues, including:
Amber or yellow
Red
Brown
Black
Semi-Dry Processing
The semi-dry processing method is sometimes known as wet hulling, and its use is prominent throughout Indonesia, particularly in Sumatra. These are the key aspects of this technique:
Picked cherries are either dried fully intact (a la natural coffees) or pulped
With a residual moisture level of 20%-25%, the still-tacky beans are taken to hulling mills to have their parchment removed (hence the term wet hulling)
This is in contrast to dry-processed (fully natural) beans, which are not hulled until their moisture level drops to 11%-12%
After their parchment has been stripped, the partially processed beans are dried further to lower their moisture level to 11%-12%, which is the normal threshold for export
The signature deep and earthy flavor profile that many Indonesian coffees are known for is said to be largely the result of this unique processing method. A handful of producers in other growing regions are turning to semi-dry processing methods as a means of conserving water or to differentiate themselves from a branding perspective.
Final Thoughts
From planted seed to roasted bean, coffee undergoes a monumental transformation in its long and difficult journey. We hope that by pulling back the curtain on the laborious processes of coffee production, we've made your next cup of coffee that much more rewarding and satisfying.
Comments