Introduction to Coffee Bean Varieties and Origins, Main Components of Coffee and Their Effects

Coffee Bean Varieties and Origins: What's Actually Inside a Coffee Bean?

Coffee trees are flowering plants of the genus Coffea, in the madder family (Rubiaceae). Roughly 120 Coffea species are known today, ranging from small shrubs to trees 18 meters tall. Wild species grow scattered across the tropics, and new ones are still being discovered. Strictly speaking, though, only two species have ever been cultivated on a large scale for coffee production: Arabica and Canephora (better known as Robusta). A handful of countries, such as the Philippines, also grow a third species, Liberica, mainly for domestic consumption.

About 70% of the world's commercially grown coffee is Arabica, and up to 7 million tons of coffee are roasted each year. Robusta accounts for the rest, with major producers including India, Java and Sumatra in the Indonesian archipelago, and Vietnam — Vietnam alone supplies nearly half of the world's Robusta and ranks as the second-largest coffee-producing country after Brazil.

Canephora beans are round, short, and oblate-elliptical. They carry roughly twice as much caffeine as Arabica beans but less fat and less sucrose, giving a sharper bitterness with a faint wheat-like aroma.

Polysaccharides

The largest component of green coffee is polysaccharides, at 35%–45%. Despite the name, they are not sweet at all — these are the structural fibers that form the plant's skeleton. Polysaccharide content differs noticeably between Arabica and Canephora.

Proteins

Proteins make up about 12% of the bean. Together with polysaccharides, they form the structural framework of the plant, and here again the levels differ markedly between the two species.

Fats

Green coffee contains fats composed chiefly of linoleic acid and palmitic acid. Arabica is the fattier of the two at around 20%, while Canephora reaches at most 10%.

Sugars (Sucrose)

Sucrose can reach 10% in Arabica but only 3%–7% in Canephora — one reason Arabica tastes noticeably sweeter.

Chlorogenic Acid

Arabica contains 5%–8% chlorogenic acid, compared with 7%–11% in Canephora. Chlorogenic acids are a diverse family, and some members occur only in Canephora.

Other Acids

Beyond chlorogenic acid, the bean contains citric, malic, quinic, phosphoric, and other acids, which together account for only about 2%.

Caffeine

Caffeine runs from 0.9% to 1.4% in Arabica, while in Canephora it is typically around 2% and can exceed 3%.

Amino Acids

Amino acids make up 1%–2% of the bean and include aspartic acid and glutamic acid, among others. Their proportions differ between the species, and together with sugars and chlorogenic acids they influence how each species browns and develops flavor during roasting.

FrontStreet Coffee Recommendation

Want to taste what a top-grade Arabica actually delivers? FrontStreet Coffee recommends our Ethiopia Guji Natural "Huakui" (Flower Blossom) lot. It is built on Ethiopia's most common heirloom varieties, so bean sizes vary naturally, and the classic natural process brings out an elegant floral note with vivid fruit: cream strawberry, mango, jackfruit, citrus, and blueberry — the ripe tropical-fruit character typical of natural Sidamo/Guji beans. It was precisely this rich berry fragrance that won first place in that year's TOH green bean competition, and the lot remains a standout for combining genuine deliciousness with an friendly price.