What Is a Coffee Bean? The Anatomy of The Coffee Cherry

Where does your coffee come from? You may know that coffee is a plant and recognize that the beans came from a bright red coffee cherry. But what is inside that coffee cherry and what does it mean for your cup?

The different parts of the coffee cherry have an impact on processing method and on your coffee’s final profile. Let’s take a look at the basic anatomy of the coffee cherry to better understand our daily brew.

Ripe coffee cherry

A ripe coffee cherry.

UNDERSTANDING THE COFFEE PLANT

The beans we roast, grind, and brew to make coffee are the seeds of a fruit. The coffee plant produces coffee cherries, and the beans are the seeds inside.

Coffee trees can naturally grow to over 30 ft/9 m. But producers prune and stump plants short to conserve the plants’ energy and to help harvesting. Smaller trees have better yield and quality in a limited space.

Each tree is covered with green, waxy leaves that grow in pairs and coffee cherries grow along its branches. Depending on the variety, it takes three to four years for a coffee plant to produce fruit. The National Coffee Association USA states that the average coffee tree produces 10 lbs of coffee cherry per year, which results in around 2 lbs of green beans.

But there are different varieties of coffee and their beans have many different characteristics. Size, flavor, and disease resistance vary, among other factors.

Ripe and unripe coffee cherries on a branch.

THE LAYERS OF A COFFEE CHERRY

A coffee cherry’s skin is called the exocarp. It is green until it ripens to a bright red, yellow, orange, or even pink, depending on variety. Green coffee cherries shouldn’t be confused with green coffee beans, which are the unroasted seeds from inside the ripe coffee cherry.

Beneath the cherry skin is a thin layer called the mesocarp, more commonly known as the pulp. Mucilage is the inner layer of the pulp. There’s also a layer of pectin underneath the mucilage.These layers are full of sugars, which are important during the fermentation process.

Then we reach the coffee seeds, which are technically called the endosperm but that we know better as beans. There are usually two beans in a coffee cherry, each of which is covered by a thin epidermis known as the silverskin and a papery hull that we call parchment (technically the endocarp).

The parchment is usually removed in hulling, which is the first step in the dry milling process. Machines or millstones are used to remove any remaining fruit and the dried parchment from the beans. But sometimes green beans are sold with this layer intact as parchment coffee.

The silverskin is a group of sclerenchyma cells that are strongly attached to the beans. These cells form to support and protect the seed. They come off during roasting, when they are known as chaff.

Coffee cherries being depulped.

Sometimes there is just one seed inside a coffee cherry and it is rounder and larger that usual. This happens in about 5% of coffee cherries and the beans are known as peaberries.

Peaberries can be an anatomical variation of the plant or they can form when there is insufficient pollination and one ovule isn’t fertilized. Sometimes the seed simply fails to grow, whether due to genetic causes or environmental conditions. Peaberries usually occur in the parts of the coffee plant that are exposed to severe weather conditions.

There is some debate over whether peaberries have a sweeter and more desirable flavour and they are sometimes sold at a premium. Regardless of whether you think they taste different, their rounded shape allows for better rolling in the roasting drum. So it’s best to keep them apart from other beans to avoid an inconsistent roast.

Dry parchment coffee.

HOW ANATOMY IMPACTS YOUR CUP

Coffee cherry skin and fruit is usually discarded, but sometimes they are dried to make cascara for tea and other products.

It is difficult to remove skin and mucilage from coffee beans and different processing methods have developed to do so. Each method has an effect on the flavour and profile of the final coffee.

For example, washed coffee has all of the fruit flesh removed before drying. But in natural coffee the fruit flesh is removed after drying. In honey and pulped natural processing, the skin and sometimes part of the mucilage is removed before drying but the remaining mucilage and other layers are removed after.

coffee being washed
Coffee beans being washed.

Leaving the mucilage on results in sweeter coffee with more body. It’s easier to understand why if we compare both dry and wet post-harvest processes.

When coffee cherries are taken from the branch, they start to germinate. This uses the sugar in the seed. Germination stops when drying begins. Natural processed coffees go to the drying terrace earlier than pulped naturals or washed coffees. Because of this, more sugars remain in the naturals and you end up with a sweeter bean.

Washed coffees have clean, more consistent flavours that can show off a lot of acidity. Natural coffees have a lot more fruitiness, sweetness, and body.

The sugars of the mucilage also ferment during both dry and wet processing, and this has an impact on the final flavor. Without careful monitoring and consistent drying, the unpredictable process of fermentation can undesirable qualities.

Yellow coffee cherries
Yellow coffee cherries.

Understanding the basics of the coffee cherry can help you better understand production, processing, and roasting. Next time you are choosing between a natural processed and washed coffee, you can have more confidence in knowing what that means and its impact on your cup.

- Written by Veronica Belchior with Hazel Boydell

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Get to Know The Coffee Plant

When we sip on that delicious latte or filter brew, it’s easy to forget that our favorite drink comes from a plant. Yet millions of coffee trees grow around the world, their fruit powering us through the day.

But what does a coffee plant actually look like? How many varieties are there? And how do the flowers and cherries affect the drink we consume every day?

Read on to find out!

Young coffee seedlings still in bags at Finca San Jerónimo, Guatemala.

A SHORT HISTORY OF COFFEE

What country comes when you hear the word “coffee:” Colombia, Brazil, Indonesia? Actually, the coffee plant originated in Ethiopia.

Over the centuries, coffee spread throughout Africa and the Middle East and from there across the globe. There are dozens of stories about how this happened, from saints sneaking beans out of Yemen to European powers replanting it throughout their colonies. What seems to be undeniable is that empires had a significant role to play.

Fast-forward to today. Coffee is an integral part of crop economies in parts of Africa, Asia, and Latin America. Non-producing countries also thrive on coffee, roasting and consuming vast quantities every single day.

But what actually is this drink? What is it made of?

Coffee seedlings at Finca San Jerónimo, Guatemala.

WHAT DOES THE COFFEE PLANT LOOK LIKE?

The name “coffee bean” is a lie: coffee is a seed. You’ll find two (normally) of these seeds inside each cherry-like fruit of the coffee plant.

The coffee plant could also be categorized as a tree since it has the ability to grow up to about 9 meters. But on coffee farms, it tends to be cut short to make it easier to harvest. As a result, it often looks more like a bush.

  • The Branches & Leaves

From the main trunk of the coffee plant, you’ll see primary, secondary, and tertiary horizontal branches. From these, dark green, waxy leaves grow in pairs.

Ricardo Alvarez, an agronomist at Finca Los Tres Potros in El Salvador, tells me, “The leaf is fundamental for the plant since that is where photosynthesis happens.” In other words, no leaves would mean no energy. And without energy, the plants would never be able to grow the delicious cherries that contain our coffee beans.

  • The Flowers

Once the coffee plant is about three or four years old, it will flower for the first time. Small, delicate, white flowers will grow where the leaves and branches join, releasing a sweet aroma.

Alvarez tells me, “The flowers are where the sexual organs are located.” In other words, the leaves and flowers help the coffee plant reproduce and sustain itself.

Coffee plants flower in a far in Honduras. 
  • Cherries

Six to eight weeks after pollination, a cherry-like fruit will appear where the flowers were located. The unripe cherries are green; over time, they turn red, yellow, orange, or even pink, depending on the variety. And as they ripen, they will grow increasingly sweeter.

Oh, and the caffeine content in the cherries? That actually works as a deterrent against – most – predators. (Unfortunately, it also attracts one of coffee’s worst pests: the coffee borer beetle, which survives on caffeine.)

Within the cherry, you’ll find multiple layers. Alvarez says that it has “an exocarp, which is the actual cherry, then we have a mesocarp which is where the mucilage is.” And within the mucilage lies the seeds we can’t face Monday morning without – coffee beans!

  • Seeds

Inside every cherry, you’ll find two small seeds – unless it’s a peaberry or otherwise defective, of course. A peaberry is when the seeds are joined: instead of two almost peanut-like ones, you’ll have a larger, rounder, pea-shaped one. This happens to around 5% of seeds.

These seeds are the coffee beans. They go through extensive processing to remove the fruit and mucilage, before being dried, roasted, ground, and finally turned into our favourite beverage.

But not all coffee plants are the same…

Healthy coffee seedlings ready for grafting, a process that helps make coffee plants stronger.

THE DIFFERENT KINDS OF COFFEE PLANTS

Coffee has over a hundred different species, and each species can be further divided into varieties. And all of these have an impact on how the coffee tastes, how much caffeine it has, and how it grows.

  • The 2 Main Coffee Species: Arabica & Robusta

Arabica is the most commonly consumed coffee in the world, accounting for about 70% of the industry. It’s known for its quality flavors and aromas; ICFC Panama biologist and coffee value chain analyst Valentina Pedrotti says, “In the specialty market, you go with Arabica.”

Compared to Robusta, it:

  • Is more sensitive to the weather
  • Is more susceptible to pests
  • Thrives at lower temperatures (which often correlate with higher elevations or being grown in the shade)
  • Usually produces fewer cherries
  • Has less caffeine content
  • Tends to be sweeter, more complex, and more aromatic

Robusta, or Canephora, is a more durable, robust tree. It accounts for about 30% of the coffee industry. Compared to Arabica, it:

  • Is more resistant to diseases and pests
  • Has a higher caffeine content
  • Thrives at slightly warmer temperatures
  • Has a higher yield, with more cherries and therefore more seeds; however, this means the individual cherries don’t get as many nutrients and so the coffee is often of a lower quality
  • Tends to be bitter
Healthy coffee plants at Finca San Jerónimo, Guatemala.
  • The Great Big World of Coffee Varieties

Unlike species, we consume numerous coffee varieties. Next time you buy a bag of specialty coffee, look at the label: it may tell you which one you’re drinking.

Some of the most common ones include Typica, Bourbon, and Caturra. And then there’s Gesha/Geisha, which is probably the most famous variety of all. This exquisite coffee is known for its delicate floral flavors and aromas, along with a tea-like body. The green beans have also been sold for as much as US $803/lb.

The coffee industry also sometimes creates hybrid varieties. As Pedrotti says, these are created when the industry “sees the necessity, or the market, for fusing coffees together.” And the aim? Disease resistance, higher productivity, and better flavour.

Lempira coffee cherries ripen on the branch. Credit: Maren Marbee via Flickr, CC BY 2.0

THE LIFE OF A COFFEE PLANT

Pedrotti tells me that a coffee plant could live for up to 80 years. But on a commercial farm? Alvarez says that you might expect them to last for 20 to 30 years, depending on how they’re cared for.

For the first few years of a tree’s life, you shouldn’t expect great productivity. Remember, it won’t flower until it’s three or four years old.

All coffee trees started life as those very same seeds that we roast and brew every day. As it grows, you’ll see its distinctive shoots and bright green leaves. Most producers keep young coffee trees in nurseries until the seedlings are ready to be planted on the farm.

The coffee leaves of a healthy coffee tree in a Guatemalan farm 

Once a coffee plant is mature, it will produce flowers; this normally happens shortly after heavy rainfall. And then, after the flowers, comes the cherries. In some countries, such as Colombia, the climate means that the trees flower twice a year – something that, in turn, leads to two harvests a year.

Arturo Aguirre of Finca El Injerto, Guatemala tells me that the producer and farm staff must learn to identify when coffee is ready for harvesting.

  • For Arabica coffee, the time from flowering to harvesting is approximately nine months
  • Robusta coffee can be harvested two to three times each year, depending on climate and soil
A coffee nursery at Fazenda Bela Epica, Brazil.

The coffee plant, with its bright cherries and delicate white flowers, is a beautiful sight. Perhaps it’s a strong low-altitude variety or a delicate but flavorsome high-altitude one, a young seedling or an old giant, full of ripe fruit or simply dark green leaves. Either way, it’s thanks to this tree that we can enjoy our daily brew and millions of people around the world have a living.

-- Written by Miguel Regalado

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