Coffee is a globally cherished beverage, enjoyed by billions each day. Many consumers don’t realize that the “beans” used to create their daily cup are not true beans, but rather seeds from a specific type of flowering plant.
The Coffee Plant: Origin and Characteristics
The coffee plant belongs to the genus Coffea, part of the Rubiaceae family, which includes over 120 species. These plants are evergreen shrubs or small trees, characterized by their dark green, waxy leaves that grow in pairs along the branches. Small, fragrant white flowers, often described as jasmine-like, appear in clusters where the leaves meet the stems, eventually giving way to the fruit.
Most Coffea species are native to tropical and southern Africa, as well as tropical Asia. Commercial coffee cultivation thrives within the “Coffee Belt,” a region situated between the Tropic of Cancer and the Tropic of Capricorn. Ideal growing conditions involve consistent temperatures (18°C to 28°C), steady rainfall (1,500 to 2,500 millimeters annually), and well-drained, slightly acidic soil. While coffee plants can live for decades (30 to 40 years), they are commonly pruned to 1.5 to 2.1 meters (5 to 7 feet) on farms for easier harvesting.
From Flower to “Bean”: The Coffee Cherry Explained
What is commonly referred to as a “coffee bean” is actually the seed found inside a fruit, known as a coffee cherry. After the delicate white flowers are pollinated, they develop into these small, round fruits. A coffee cherry undergoes a color transformation as it ripens, typically changing from green to a vibrant red, although some varieties can ripen to yellow, orange, or even purple.
The coffee cherry has several distinct layers. The outermost layer is the exocarp, or skin, protecting the fruit. Beneath the skin lies the mesocarp, a fleshy, sweet pulp rich in sugars and water. Further inward is a sticky, gelatinous layer called the mucilage, also containing sugars and pectin. Encased within these layers are typically two seeds, the coffee “beans.” Each seed is individually protected by a papery hull known as the endocarp, or parchment, and a very thin, innermost layer called the silverskin. In about 5% of coffee cherries, only a single, rounder seed develops, known as a peaberry.
Key Coffee Species: Arabica and Robusta
While numerous Coffea species exist, two dominate global coffee production: Coffea arabica and Coffea canephora (Robusta). These two species have distinct characteristics and growing requirements.
Coffea arabica, accounting for approximately 60% to 75% of worldwide production, is valued for its complex flavor profile. It grows at higher altitudes (1,200 to 2,200 meters above sea level) and thrives in cooler temperatures (15°C to 24°C). Arabica beans are generally oval-shaped and produce a coffee known for its aromatic complexity, smoother taste, higher acidity, and notes of fruit and sweetness. However, Arabica plants are more delicate and susceptible to diseases and pests, requiring specific care.
In contrast, Coffea canephora (Robusta) makes up about 25% to 40% of the global coffee market. Robusta is a hardier plant, more tolerant of warmer climates (24°C to 30°C) and capable of growing at lower altitudes (200 to 800 meters). Robusta beans are rounder and yield a coffee with a stronger, bolder, and more bitter flavor, sometimes described as earthy or rubbery. This intensity is partly due to its significantly higher caffeine content, which can be nearly double that of Arabica beans. Robusta is frequently used in espresso blends to create a richer crema and is a common choice for instant coffee.