Three Major Types of Coffee Beans - Differences Between Main Coffee Growing Regions and Coffee Bean Varieties' Flavor Characteristics

Today, Arabica beans account for seventy percent of the world's coffee production, and Arabica beans are widely recognized as the coffee beans with the best flavor. Besides Arabica coffee beans, the other coffee varieties that have been "domesticated" by humans include Robusta and Liberica. In this article, FrontStreet Coffee will discuss these three coffee bean varieties.

With a simple online search, you can find the distinguishing characteristics between Arabica, Robusta, and Liberica beans. Arabica beans are described as oval-shaped, relatively slender and flat, with an "S"-shaped center line. Ordinary Arabica fruits typically contain two coffee beans, which is why Arabica coffee beans have one flat side. Of course, there are exceptions—some coffee fruits contain only one bean, and these beans appear round and full, somewhat resembling Robusta's appearance. These are called peaberries and are generally smaller than flat beans. If normal flat beans are 17-18 screen size, peaberries are approximately 14-15 screen size.

Arabica Coffee Varieties

First, let's talk about Arabica coffee beans. Arabica is currently the most comprehensive classification of coffee bean varieties you can find in the specialty coffee industry. Friends often ask FrontStreet Coffee whether Typica or Arabica is better, which reflects how people, after encountering specialty beans, tend to equate the commonly heard Arabica with Typica. However, Typica is just one branch of Arabica and one of the most original coffee varieties. Other well-known coffee varieties we're familiar with—Bourbon, Gesha, SL28 & SL34, Caturra, Catuai, etc.—are all branches of Arabica varieties. Because there are too many branches, FrontStreet Coffee will first discuss several Arabica coffee varieties just mentioned.

Typica

As the most ancient coffee variety, Typica's physical characteristics are often used as the model features for Arabica species. That is, oval-shaped, relatively slender and flat, with an "S"-shaped center line. Of course, sometimes special processing methods can also change the appearance of coffee beans. For example, the wet-hulling processing method frequently used in Indonesia, whose biggest characteristic is removing parchment after the washing process before drying. Using machines to hull the parchment can subject beans to mechanical pressure, causing them to crack and take on a cloven-hoof shape. Through cupping Typica coffee beans, FrontStreet Coffee has found that regardless of the growing region, Typica's sweet and clean coffee flavor profile is consistently well-expressed.

Bourbon

Bourbon is a natural variant of Typica, and the biggest change in its coffee beans is from the original elongated shape to a round shape. This is what we often call round Bourbon, with particle size similar to Typica. Its direct single-gene mutant varieties, such as Yellow Bourbon, Pink Bourbon, Caturra, Pacas, and Villalobos, have all well-inherited the appearance characteristics of Bourbon coffee beans (some Caturra, Pacas, and Villalobos, after multiple artificial breeding cycles, may show slightly more elongated bean shapes). The biggest difference between Bourbon and Typica in appearance is that Bourbon has broader leaves, bears smaller coffee fruits, and has more intensive production. Therefore, compared to Typica, Bourbon's coffee fruits are smaller and rounder in appearance. Bourbon is often the champion in American specialty coffee cupping competitions.

SL28 & SL34

SL28 is a single variety selected in 1935 from the drought-resistant population of Tanganyika varieties. The SL28 variety is suitable for medium to high altitude areas, has drought resistance capabilities, but is sensitive to major coffee diseases. SL28 beans resemble Bourbon varieties—round and thick. Recent genetic tests have also confirmed that the SL28 variety belongs to the Bourbon genetic group.

SL34 was initially selected in the late 1930s at Scott Agricultural Laboratories in Kenya. SL34 was selected from a tree on the Kabete Loresho estate in Kenya, and this tree was called the "French Missionary." SL34 beans resemble Typica varieties. FrontStreet Coffee sifts through Kenyan beans to find those with Typica-like appearance—slender, oval-shaped, and relatively flat when viewed from the side. Recent genetic testing indicates that SL34 is related to the Typica genome. Through cupping, FrontStreet Coffee believes that SL34 has similar flavor characteristics to SL28—besides complex and varied acidity and excellent sweet finish—it has a heavier, more intense body than SL28, and is cleaner.

Gesha

The appearance characteristics of Gesha coffee need to be described in two parts. First is American Gesha, represented by Panama's Hacienda La Esmeralda. Second is African Gesha, represented by Ethiopia's Gesha Village Coffee Estate. Hacienda La Esmeralda is famous for Gesha, and its Gesha coffee's most prominent appearance feature is being slender, pointed at both ends, and plump and full in the middle. Some high-quality Gesha beans can even be as large as Pacamara (18-19 screen size), making their identification characteristics very obvious. Through cupping Gesha coffee, FrontStreet Coffee finds its floral and citrus aromas truly captivating.

Caturra

Caturra is a variant of Bourbon, discovered in Brazil in 1937. It has better production capacity and disease resistance than Bourbon, with shorter plants that facilitate harvesting. It is highly adaptable and doesn't require shade trees, making it suitable for cultivation from low altitudes of 700 meters to high altitudes of 1700 meters. While it has strong altitude adaptability, the higher the altitude, the better the flavor, though production capacity decreases accordingly.

Catuai

Catuai is a coffee variety artificially hybridized in 1949 from yellow Caturra and Mundo Novo, originally called "H-2077." Catuai has good resistance to disasters, particularly wind and rain. Due to its smaller plant size, it can be planted at double density, and the short plants make pest and disease treatment relatively easy. Catuai grows vigorously, has low height, but is susceptible to leaf rust disease.

Robusta

Although both Arabica and Robusta grow in the coffee belt—between 45 degrees north and south latitude—we often say that Arabica is cultivated at altitudes above 800 meters. Arabica has high requirements for growing conditions and weak resistance to pests and diseases. Robusta is cultivated at altitudes below 800 meters and has extremely strong adaptability with high resistance to pests and diseases. This raises two questions: resistance to pests and diseases, and adaptability to the environment.

The global coffee growing belt lies between the Tropics of Cancer and Capricorn, and Robusta is no exception. However, Robusta's growing conditions are not as demanding as Arabica's. Robusta can grow at lower altitudes and higher temperatures. It grows faster than Arabica and has higher tolerance to extreme weather conditions. Robusta is cross-pollinated, and pollination involves genetics. Typically, cross-pollinated plants have higher quality—offspring produced through cross-pollination inherit genetic traits from both parent plants, potentially generating new characteristics that help it survive in changing environments. Robusta's strength lies in its ability to continuously change genes to adapt to the environment.

Main Differences Between Robusta and Arabica

Robusta's caffeine content ranges from 2.7% to 4%, twice that of Arabica. Caffeine serves as a natural pesticide for plants, protecting them from most insect damage. For humans, caffeine is the world's most commonly used psychoactive substance, while in nature it functions as a natural insecticide that can paralyze insects consuming caffeine-containing plants.

Meanwhile, higher caffeine content also reduces the richness of coffee flavor. Robusta has higher caffeine, amino acid, and chlorogenic acid content. Chlorogenic acid is the source of bitterness, so Robusta naturally lacks the elegant aromatic fragrance unique to Arabica beans. Through cupping Robusta coffee beans, FrontStreet Coffee has found that its flavor profile is richer and has a deeper body compared to Arabica, with flavors of walnuts, peanuts, hazelnuts, wheat, grains, and even pungent earthy and rubber notes.

Liberica

Liberica originally grew in the low-altitude forests along the coast of Liberia in West Africa, and its name comes from its place of origin, Liberia. Liberica coffee trees are much taller than Arabica or Robusta varieties, reaching heights of 6-20 meters. The coffee fruits produced by Liberica are also larger than those of the other two coffee species, which is why Liberica is also called the large-fruit species. Its coffee flavor is famous for its intense woody and smoky notes. Liberica, Arabica, and Canephora (Robusta) are collectively known as the three major coffee species in the commercial coffee market. Liberica coffee accounts for 2% of world consumption, appearing insignificant compared to Arabica (approximately 75%) and Robusta (approximately 20%).

Among all coffee species, Liberica has the lowest caffeine content. Robusta has the highest, containing 2.26 grams of caffeine per 100 grams of beans. Arabica coffee follows with 1.61 grams of caffeine per 100 grams of beans. Liberica contains only 1.23 grams of caffeine per 100 grams of beans. Despite Liberica's lower caffeine content than Arabica and Robusta, its flavor is indeed less approachable. The main flavor notes of Liberica coffee are the heavy sensation of nuts and dark chocolate and smoky aroma. It has an intense, robust flavor, even with earthy and woody notes. Compared to Arabica's bright and pleasant flavor, Liberica's flavor appears heavier and more substantial.

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