Coffee is one of the world's most popular drinks, an extraordinary drink we all enjoy daily. Coffee is a beverage we make from brewing roasted and grounded coffee beans. To brew some coffee, we need to put about 60g of somewhat medium-ground coffee into a paper filter and pour over one liter of nearly boiling water to make a batch of regular black filter coffee.
We often serve and enjoy coffee in a 6oz (180ml) or 8oz (240ml) ceramic cup or mug, next to milk or sugar, to sweeten it if we like.
To many of us, mornings are a time for brewing a great cup of coffee to start the day. Because of coffee, our mornings share a ritual and begin the same with billions of people worldwide. We all love and enjoy the smell of freshly ground coffee beans from the kitchen first thing in the morning.
Coffee also has become an ever-present aspect of our society. We don't just consume it at home.
We also enjoy it throughout the day at work, coffee shops, restaurants, bars, and many other places where we can gather to relax and socialize with colleagues, friends, or family.
As a commodity, coffee is widely available in all the countries of the world, and we can find it in any local store. When buying coffee, whether picking it up from a store or purchasing a specialty coffee, we encounter choices that we sometimes don't fully understand.
Usually printed on the coffee bag, we'll find descriptions and details about the beans' variety and the roast level, the region and the country of origin, and how the farmers have processed the beans after being harvested.
But before we examine any of the information printed on the coffee bag, we'll need to get familiar with the coffee plant itself, its fruits, and how and where it grows in nature.
The Coffee Plant
The coffee plant or Coffea is a medium-sized tree (shrub) native to the tropical and southern parts of Africa and Asia, but it has been introduced and grown in almost all countries that are part of the coffee belt region.
The coffee belt region spreads 25 degrees north and 30 degrees south of the equator and has the perfect temperature and climate for coffee plants to flourish.
The coffee tree will flower in spring with little white flowers that later develop into fruits. The fruits of the coffee tree are called coffee cherries.
Coffee cherries are round and about 3/4 inch (2 cm) long fruits. They are green initially, but they turn yellow and then red as they mature. They will turn dark red when fully ripened and are ready to be harvested.
The inside of the coffee cherry usually consists of two seeds that we call coffee beans covered in a thick gooey mucus layer. Coffee cherry is an edible fruit both for humans and animals too. When eating a coffee cherry, we will find that the outer skin of the cherry is a bit rough, but the mucus layer inside it tastes sweet and is rather pleasant. The two seeds, or beans, are hard to crack but edible. When we roast the beans, they become dry, brittle, and easier to break or grind.
The Varieties of Coffee Beans
Today, there are over 120 varieties of the Coffea plant, but the most popular and widely grown worldwide are Arabica and Robusta.
Coffea Arabica, or just Arabica beans and their subtypes, are grown in tropical regions near the equator.
Arabica grows at higher altitudes, and the plant is at its finest in the shade of taller plants because it needs indirect sunlight to flourish.
Often, farmers plant more towering trees like palm or eucalyptus trees to cast down a shadow on their coffee plantations with Coffea Arabica and its varieties.
Coffea Arabica has many subvarieties, but Geisha, Typica, and Bourbon are the most widespread. Arabica beans are the most widely farmed coffee beans, accounting for up to 60% of all the coffee consumed worldwide.
Brazil is the largest producer of Arabica coffee beans in the world [1]. They are characteristic of a smooth, sweet taste with just a hint of acidity.
Coffea canephora, commonly known as Robusta, is the second most common type of coffee bean. It is widely grown in the lower regions of Africa and Indonesia.
Nonetheless, it is a pretty standard tree on the coffee farms in all the countries in the coffee belt region due to the plant being less susceptible to diseases and illnesses than the Coffea arabica.
With their harsher, more pungent, and bitter taste, Robusta beans are inferior to the Arabica beans tastewise, so sellers tend to blend them with other types of beans. Today, Robusta beans comprise 40% of all the coffee production in the world.
Liberica [2] and Excelsa coffee varieties are grown in parts of Southeast Asia, South America, and Africa, and together, they make a tiny percentage of the coffee produced and consumed worldwide. Because of low production, these beans are prized higher than Robusta and Arabica beans at the market.
The Roast Level of the Coffee beans
Roasting coffee beans is very important. Coffee made from unroasted coffee beans is undrinkable because of its taste. When the beans are raw, they are green, solid, and have a woody grassy flavor that is unpleasant to drink.
There are three types of roasts in coffee: light, medium, and dark. To roast the coffee beans, we must expose them to high heat, to temperatures above 356°F (180°C).
While constantly mixing them, we progressively increase the heat to 482°F (250°C) depending on the roast we try to make. Besides the heat, the roasting time varies for different roasts.
For a light roast, time can run from 7 to 9 min, and it can go up to 18 to 19 min for very dark roasts and somewhere in between are medium roasts, so-called City roasts.
With roasting, complex chemical reactions happen inside the beans that directly affect the coffee flavor we later brew. And for that reason, roasting aims to develop the coffee bean's natural flavors and enhance them by balancing the sweetness, bitterness, and acidity.
Dive Deeper: From Bean to Brew: How Different Roast Levels Transform Your Coffee
Each little raw (green) coffee bean contains about 10% water at the beginning of the roasting process. The beans become dried of their inner water content in the first 3 minutes of the roasting. And at that stage, their smell or appearance has almost no changes.
After drying, browning reactions start to develop on the outside of the bean, but the innards of the bean are still undercooked. At this time, the coffee from those beans will still be unpleasant to drink, with a grassy, sour, and bitter taste.
As browning increases, water vapor, and gases build up pressure inside the bean. Once that pressure reaches a certain point, the bean breaks open, producing a cracking sound, and the bean increases in volume. When the beans begin to crack, most coffee flavors start to develop, which we call the "first crack" stage.
Continuing to roast the coffee beans for longer, they will crack a second time. At that point, the bean's oils will come out to the bean's surface, and much of the bean's natural acidity will get lost.
Different flavors will start to develop at the second crack, which are more by-products of burning and charing than coffee's inherent flavors.
We often call beans roasted up to and beyond the second-crack French or Italian roasts, which are high in deep caramel and smoky flavors but deprived of the coffee's intrinsic flavor.
The following video by James Hoffmann, the author of the books "How to Make the Best Coffee at Home" and "The World Atlas of Coffee," provides a detailed explanation of the coffee roasting process. (Affiliate Links to Amazon)
The Blends of Coffees and the Single Origin Coffees
Mixing different coffees is an old concept that has evolved through the years. Blends of coffee mean taking two or more batches of coffee beans of various origins and varieties and mixing them, sometimes before roasting, but more often after roasting them each separately.
Throughout the history of coffee, roasters consistently combine lesser quality coffee beans with higher quality beans to conceal their coffee beans' imperfections, giving the blends of coffee a lousy reputation.
Today, roasters that produce specialty coffees combine two or more different types of coffee beans that are also of high quality. By doing so, they assemble blends that delightfully complement each other, creating a great harmony of flavors that don't compromise the quality of the bag of coffee beans.
Roasters produce some mixtures of coffee, mainly for espresso and espresso-based drinks, to taste excellent when diluted with milk or water, as for pour-over and drip coffees that we most typically brew with light to medium roasted single-origin coffee.
When a bag of coffee has the label single-origin coffees, that means that the beans inside are coming from a single location. The uniqueness of the place where a single-origin coffee is grown gets expressed through the coffee's flavor.
Many things influence the taste of the single-origin coffee produced in a particular region, such as coffee's variety, the method of processing the beans after the harvest, the roast level of the beans, etc.
But the coffee also gets its terroir, a distinct taste imparted from the area it comes from, which often gets described in the coffee beans bag.
For example, we will often find descriptions like:
- Ethiopian coffees are often punchy, fruity, and sweet.
- Indonesian coffees express a prominent earthiness and savory taste.
- Colombian coffees taste caramel, chocolate, nuts, and mellow acidity notes.
- Kenyan coffees taste sharp and vibrant with lemony and citrusy notes and berry tones.
- Sumatran coffees have funky flavors like earthy, mushroomy, dried herbs, and spicy.
- Brazilian coffee taste profile includes caramel and sweet chocolate notes and is low in acidity.
The list of where coffee originates and how it tastes is extensive, and it takes time for one to get familiarized with the taste of the beans that come from the different coffee-growing regions in the world.
Single-origin coffee beans, contrary to blends, are almost always light to medium roasted, allowing the inherent flavor of the beans to push through in the coffee when we brew them.
The Processing of the Coffee Beans
After harvesting the coffee beans, the next step that farmers and coffee producers undertake is processing the coffee beans.
Processing coffee beans is a method that coffee producers exploit after the harvest to allow for a controlled fermentation of the sugars in the mucilage inside the coffee cherry to infuse the coffee beans with flavors.
All of the methods that the producers use for processing the beans start with selecting only the ripest and freshest coffee cherries. They perform this selection by submerging the cherries in water; the ones that float to the surface are considered defective, and producers discard them.
The cherries that stay submerged underwater are collected and proceed further. How coffee producers process the beans will significantly impact the taste of the coffee. There are many coffee processing methods, but coffee producers and farmers commonly exploit the four most used worldwide.
- Washed Coffee Processing
- Natural Coffee Processing
- Honey Coffee Processing
- Wet-Hulled Coffee Processing
Washed Coffee Processing
Wet or Washed Coffee Processing coffee producers commonly practice throughout Africa and Central and South America.
After harvesting, producers put the cherries into a container or a basin and submerged them in water to wash them and perform a so-called floating test. Coffee fruits that stay submerged at the bottom are considered good, producers, transfer into a de-pulping machine. The cherries that float are considered as defective and are discarded.
A de-pulper squeezes the seeds through the tough skin and pulp of the cherry. Coffee producers de-pulp the coffee beans as soon as possible, usually between 8 to 12 hours after the harvest.
When the beans are processed, they exit the de-pulper covered in mucilage, the sweet and sticky material that naturally surrounds them inside the cherry.
That mucilage producers later remove thoroughly with washing, but not until they leave the beans covered with it to ferment overnight in a fermentation tank at a temperature of between 68°F (20°C) and 75°F (24°C).
This fermentation is crucial because it will give flavor to the coffee, and it is also helpful because it will soften the mucilage and make it easier to remove in the washing process. Fermentation happens with all types of coffee processing, but it is moderate and with less velocity in washed coffee processing.
The next step is where the actual washing begins, and this process gets its name. In the container or basin where the beans were sitting overnight, producers fill it with water, and the beans are agitated and stirred until the water gets murky and sludgy.
When the water gets too dark, producers release and replace it with fresh water, and they repeat until the beans are clean of any mucilage and still in their parchment layer. Producers again perform the floating test and collect and discard any beans that begin to float to the water surface as they are considered defective.
When the coffee producers thoroughly wash the beans, they transfer them from the container onto a drying platform and lay them dispersed in a thin layer to dry.
Afterward, they mixed the coffee beans multiple times each day to ensure they dried evenly. The drying process of the beans lasts until the beans' internal moisture lowers to 10 or 12%, which takes approximately one to two weeks, depending on the weather.
When the drying finishes, the coffee beans are collected and sent off to a storage unit with the parchment unremoved. The parchment will be removed only when the coffee is ready to be exported.
Natural Coffee Processing
Natural Coffee Processing or Dry process is the oldest of all the coffee processing methods, and it is widespread and still commonly used in all coffee-growing countries.
Coffees processed with this method have a fruitier profile than coffees processed differently. The flavor of natural processed coffee is bright and resembles that of berry fruit, like blueberry, raspberry, or strawberry.
This fruity profile of naturally processed coffee comes from the more extended contact the beans have with the coffee fruit. Farmers and coffee producers select only the ripest coffee cherries and those that stay underwater when tested for buoyancy to be naturally processed.
To naturally dry coffee cherries, producers depend on dry, warm, and sunny weather, so they will not start this process if the weather conditions are not suitable. After coffee producers secure all the requirements, they pour the cherries in a thin layer on a drying platform, preferably elevated from the ground and made of mesh to allow air to circulate through the fruits.
Three to four weeks, it takes for the process of drying the coffee cherries to finish and the beans inside to reach 10 to 12% humidity. The formation of mold on the cherries is a constant concern for the producers, so they mix and rotate them several times a day.
If the weather gets too hot, producers might pile the cherries or cover them to control and regulate the fermentation and drying process. When the drying has finished, dried cherries are collected and run through a hulling machine to remove the cherries' dried skin and the bean's parchment layer. The green coffee beans are finally collected in sacks and are ready to be shipped for roasting.
Honey Coffee Processing
Honey Coffee Processing is a method of separating the coffee beans from the cherries and treating them afterward. It has only recently become more common in coffee-producing countries, especially Central America.
Like washed coffee processing, honey coffee processing focuses on choosing the ripest and most developed cherries to quickly remove their skins within 8 to 10 hours after harvesting by running them through a de-pulping machine.
But the similarities with the washed process end here, as honey processing requires beans to be spread on a drying platform to ferment with the mucilage on the parchment until the beans get dried to 11% of internal humidity.
Weather plays a crucial role also in honey coffee processing, especially in the first three days of the process when the producers want more heat from the sun to speed up the drying of the beans.
Drying the beans lasts about 2 to 3 weeks, and not accounting for the first three days requires not-so-hot weather conditions to dry the beans gradually.
There are several variations of honey-processed coffees, and all of them are described by their color. The most common are so-called Yellow, Red, and Black honey-processed coffees.
For yellow honey-processed beans, producers achieve this by drying the mucilage quickly within the first three days.
Still, producers pile the beans to make Red and Black honey processed, so the fruit mucilage has a longer time to ferment.
The longer the fruit mucilage is left to ferment, the darker the honey-processed beans are and will develop more of a flavor profile of honey-processed beans.
Tastewise yellow honey-processed beans are very mild in fruitiness and closely resemble Washed (Wet) processed beans. Red honey-processed beans tend to have a more fruity flavor. Black honey-processed beans are bright and fruity, a more delicate version of natural-processed beans, as they resemble each other very much.
Before exporting, the honey-processed beans have their parchment removed, shipping only the green beans.
Wet-Hulled Coffee Processing
The Wet-Hulled Coffee Processing method, coffee producers, use in places where the weather conditions are humid and moist to remove the coffee beans from the coffee cherries.
Coffee producers in Indonesia mainly practice this method. It is called Sumatra or Giling Basah, which translates to "wet grinding" in Indonesian.
This method removes coffee beans from the coffee cherries using a de-pulping machine. The beans that come out after de-pulping covered with mucilage are collected in bags or containers and left to ferment overnight.
Because of high humidity and rain, the producers can not spread the beans to dry completely with the mucilage and parchment still on, it will take too long, and mold formation is a concern for them.
So, after they are satisfied with the level of fermentation, producers will lay the beans in a thin layer on a platform to get them partially dry, at about 30 to 35% of internal moisture. Depending on the weather conditions, drying and preparing the beans can take a few hours to a day, but that moisture level is necessary for the next step.
Next, producers place the beans in a de-hulling machine to remove the parchment while it is still wet, hence the name Wet-Hulled Coffee Processing.
The wet-hulling machine works similarly to the de-pulping device, but it is differently calibrated to remove the parchment layer of the beans. Because of its calibration, the wet-hull machine can damage some beans when processing them, leaving them with cracks or splits on the surface.
After the beans have been wet-hulled, producers lay the now green beans again on a platform to finish drying to 10 to 12% internal humidity.
With Wet-Hulled Coffee Processing, the risks of the green beans getting mold and going bad are reduced compared to drying the beans with mucilage or parchment in humid weather.
The flavor profile of the coffee brewed with Wet-Hulled processed beans is herbaceous, earthy, and savory.
The Coffee Brewing Methods and the Grind Size of Coffee
Preparing a beverage from coffee beans is what we call coffee brewing. We use water to brew coffee and extract the soluble materials from the roasted and grounded coffee beans.
Today, there are numerous different methods to brew coffee. Many of them got their name from the coffee gear used to brew, such as Filter Coffee, French Press, Espresso, Moka Pot, AeroPress, Chemex, Hario V60 dripper, etc.
All brewing coffee methods have characteristics that come through in the taste of the brewed coffee, and we consider each of them a different brewing technique. Still, we can divide them into two major categories: immersion and percolation.
We consider immersion, the brewing methods in which the grounded coffee beans are submerged in the brewing water and are left there for some time until the water gets concentrated enough with soluble materials from the coffee beans.
And we consider, for percolation, all the methods where clean brewing water passes through a prepared bed of grounded coffee beans and extracts solubles from the coffee.
The brewing time varies from method to method, but it is strongly affected by the roast level, how fine or coarse the grounded beans are, and the temperature of the brewing water.
The purpose of grinding the coffee beans before brewing is to expose more surface area of the beans and allow the brewing water to have more contact with them throughout the brewing process. So no matter which brewing method we prefer, we need to grind our beans before we brew.
There is no strict formula for how coarse or fine we should grind our beans for any brewing method. But we have general guidelines we want to follow when trying to dial in the ground size of a particular brewing method.
| Extra Coarse | Coarse | Medium | Medium-Fine | Fine | Extra Fine |
|---|---|---|---|---|---|
| Cold brew | French press | Aeropress | Pour-over | Moka pot | Turkish coffee |
| Percolator | Chemex | Espresso | |||
| Drip coffee maker | Hario V60 | ||||
| Vacuum pot |
Continue Reading:
A Coffee Brewing Guide: The French Press
A Coffee Brewing Guide: The Moka Pot
A Coffee Brewing Guide: The Pour-over Technique
A Coffee Brewing Guide: The AeroPress
Discovering Turkish Coffee: Unveiling Tradition, Brewing Secrets, and Global Delight