Coffee owes its distinctive character to a perfect harmony between nature and human cultivation. In this exploration, we delve into the origins of the coffee plant and its precious fruit, the coffee berry, unlocking the secrets behind the world's favorite brew. Arabica and Robusta are the two most common types of coffee grown for consumption, in addition we have Liberia and Excelsa, but these types are not exported or commercialized. Join us on a journey where we focus on specialty coffee, more specifically the Arabica variety, a coffee connoisseur's delight.
Table of Contents
The coffee plant
The coffee plant belongs to the Coffea genus, which is part of the Rubiaceae family in botanic classification. A coffee plant produces its first, but limited, harvest after two years. Coffee bushes can reach heights of up to ten metres if they are not pruned. For ease of picking, farmers prune them to a maximum height of three meters.
The flower of the coffee plant develops into a fruit, the ‘coffee cherry’ or ‘coffee berry’, which takes six to nine months to ripen. There is one main harvest per year in each coffee-growing area of the world, but the influence of humidity can make a coffee plant flower several times per year. That explains why there are fruits at different stages of maturity on a single branch and therefore not all the berries ripen, ready for picking at the same time.
This leads us directly to the importance and challenge of correct harvesting. Ripe coffee fruits are usually red, shiny and firm. Immature fruits will produce a sharp and sour-flavoured coffee. Coffee made from over-ripe fruit tastes stale, over-fermented and unpleasant. So it is very important to pick the ripe berries only. You can read everything about the different picking methods in our blog 'From picking to processing, uncover the secrets of the coffee bean transformation'.
Until a short time ago, people thought that there were only about seventy species. Recently, we have discovered that there are at least 120 species. Yet only two of these 120 or more species are commercialized: Coffea arabica (arabica) and Coffea canephora (robusta). There are two other types, liberica and excelsa, but they are not exported because the quality is simply not good enough.
Types of Coffees
Arabica
Arabica is by far the most popular type of coffee and it makes up 70% of world sales. Arabica is actually the oldest coffee plant too. If you're curious about the specialty coffee you savor, delve into the details in our blog, 'Arabica coffee: what is it exactly.' Discover the fascinating history, distinctive flavors, and why Arabica remains the go-to for coffee connoisseurs. Brew your knowledge and elevate your coffee experience – Get to know the difference: arabica vs. robusta coffee.
Robusta
Robusta is, as the name suggests, a solid bean that accounts for 30% of global coffee production. Robusta is most commonly produced in West and Central Africa and South East Asia. Robusta contains twice as much caffeine* as its coffee cousin arabica and it is also much more resistant to all sorts of plant diseases. The coffee plant can withstand tropical storms and extreme heat, but grows best at a temperature between 24 and 30 °C. It takes only 2.5 kg of robusta berries to produce 1 kg of green coffee beans.
Robusta has a strong, hard and rather bitter taste with woody tones, which many people feel lacks in complexity. Robusta is therefore mainly used in blends as an easy solution for adding the necessary power to the mix. Classic Italian coffees also quite often use robusta.
As mentioned above, is robusta fairly lacking in complexity of flavours on the palette and it has a rather ‘earthy’ taste. And so it is far less fascinating for a coffee roaster to apply his or her efforts to this species. Arabica varieties have a very broad flavour spectrum, which makes working on roasting them to produce a great coffee an extremely fascinating task. That does not necessarily imply that 100% arabica means top quality by default, because it can still be poorly grown. And these days we are closely examining robusta varieties and researching the potential of this type of plant. So who knows? We might actually be discussing ‘Speciality Robusta Coffee’ next.
Liberica & Excelsa
In addition to robusta and arabica, there are two other types of coffee available, but they are not exported or commercialized. Why is that? Firstly and most importantly, these species are not really tasty and they contain way too much caffeine. Some people may think ‘Lots of caffeine, fantastic!’ – but believe us, you will be happier if you give this coffee a miss.
At the end of the nineteenth century, in view of its resistance to coffee plant diseases, liberica was planted in Indonesia as a replacement for arabica bushes that were affected by coffee rust. The plant produces berries twice as large as those produced by Coffea arabica. However, the quality of the beans is far inferior. That is why liberica coffee is usually only grown for local consumption and rarely for export.
Legend has it that liberica coffee was mainly drunk by the Vikings when they were at sea for days and needed to stay awake for hours on end. In the world of specialty coffee we work exclusively with arabica, because we believe it offers and ensures better quality. We want to introduce everyone to a sublime cup of coffee, and that is why we return again and again to the arabica varieties.
The Coffee Berry
The fruit of the coffee plant is called the ‘coffee cherry’ or ‘coffee berry’, because it has the same shape, size and colour as a berry. The fruit flesh is inside the hard shell – it is a sweet, sticky, yellow substance, which even tastes good. Coffee growers frequently use the fruit flesh as an organic compost to fertilize the crop. And it is certainly used in specialty coffee cultivation as an organic fertilizer.
The actual coffee bean lies enshrouded in the fruit pulp. There are normally two beans in a coffee berry, with their flat sides against each other, just like two peanut halves. The beans are wrapped in a very thin, translucent membrane, the ‘silver skin’. This membrane comes off the bean during roasting. Every coffee bean (and its silver skin) is further shrouded by a tough cream-coloured, protective shell or husk – the parchment or hull. This hull separates the bean from the flesh and protects the coffee bean. The parchment (or hull) must dry out until its moisture content is 12%, so that the beans can be stored properly. The parchment should not burst. At this stage, we call the beans ‘parchment coffee’. This is the best form in which to store the beans until just before the the time for exporting them.
Sometimes a coffee berry only contains a single bean, which we call the ‘peaberry’, ‘round bean’ or ‘pea bean’. Up to a maximum of 10% of a harvest might be peaberries. These beans do not have flat sides and they are often almost completely round. They are separated out, because they must be roasted differently. A peaberry is actually not as easy to roast as a regular coffee bean. And they have a different flavour. Some people claim that the aroma of this bean is better than that of its sister, the regular bean. In our opinion, because these beans get more attention through being separated out, it is easier to notice inferior ones.
Influencing Factors
Soil
The substrate that the coffee is grown on is very important. Above all, it must drain well and be mineral-rich. You can compare this concept with that of ‘terroir’ in oenology. It is a commonly held opinion that you can taste the ‘soil’ in a wine, and that applies to coffee too. You can grow coffee on two types of soil: volcanic rock substrate and laterite soil. The first soil type mainly occurs in Central America. In Africa and South America, laterite soils are the most common, which gives the ground a typically reddish colour. Each type of soil produces coffee with completely different flavour profiles. A volcanic rock substrate produces coffee with lower acidity and a more nutty flavour, while laterite soil results in coffee with a higher acidity. Each type of soil requires the addition of sufficient nutrients to produce a top-quality coffee, e.g. by using the coffee berry fruit flesh.
Altitude
The altitude at which the coffee plant grows is very important for the flavour – as we mentioned when discussing arabica and robusta. The closer the plantation is to the equator, the higher the temperature. And so it is important for growers to plant at a higher altitude, thus ensuring the ideal temperature. After all, the coffee berries have plenty of time to ripen well at a lower temperature. A slow ripening process is of paramount importance. So, the closer to the equator, the higher the arabica coffee is grown. The chart opposite shows how flavour potential is linked to plantation altitude. Of course, this does not mean that you are guaranteed to grow top-quality coffee at 1,800 metres. That height offers the potential, but to exploit that potential optimally, growers still need to take great care of all the other steps in the process.
Sun
Coffee beans mature faster in the sun, which makes cultivation more productive, but also negatively affects the quality. The sun warms the coffee plant, giving it its unique flavour. Yet the better coffees are not found in open, sun-drenched areas, but actually in the shade of other crops. Once again, this is because the ripening process is slowed down. So, you will rarely find top-quality coffee grown in sun-drenched plantations without shade.
Harvest Periods
The equatorial regions have dry and wet seasons, which means the flowering time is limited to only two seasons and is regulated by the relative humidity. The flowering period spreads over several months, which means that coffee plants in the equatorial region can flower several times a year. This is why there are often flowers and berries at different stages of development and ripening on the same bush. Close to the equator, the crop develops in different phases, and not in a particular growing season like ours. The seasons are more clearly defined in a tropical region and the harvest comes once a year. Coffee fruits need to ripen for eight to nine months after flowering to be ready for harvest.