Cherry to Cup

Coffee Fundamentals 🏆

Course 1 · Chapter 1 · Cherry to Cup: What Coffee Actually Is

A Seed, Not a Bean

Coffee is a drink made from the roasted seeds of plants in the genus Coffea. The fruit is called a cherry and the seed inside is called a bean, but Wikipedia's Coffea article points out that coffee is neither a true cherry (it is not from the genus Prunus) nor a true bean (it is not from the legume family). The article describes the fruit as an epigynous berry or an indehiscent drupe, which is botanists' way of saying a fleshy fruit that does not split open by itself.

Everyday word	What it really is	Detail
Cherry	The fruit of the coffee plant	About 1.5 cm long, ripening from green to yellow to crimson (black if left to dry)
Bean	The seed inside the fruit	Usually two seeds per fruit, lying with their flat faces together
Peaberry	A fruit with only one seed	About 5 to 10 percent of fruits

In the tropics the plant is a shrub or small tree that typically reaches 3 to 3.5 m. Most cultivated species grow best at high elevations but cannot tolerate freezing temperatures.

Two Species Do Most of the Work

The genus is large: Wikipedia says "over 120 species" in its introduction and lists 133 species and one hybrid following Plants of the World Online as of January 2026. Only two matter for the cup you buy.

Trait	Arabica (C. arabica)	Robusta (C. canephora)
Reputation	Sweeter taste, generally more highly regarded	More bitter, less flavour, fuller body (Coffee article)
Caffeine	Lower	About 40 to 50 percent more than arabica
Origin	Ethiopian highlands and the Boma Plateau of Sudan	Tropical Africa (check)
Share of world output	Roughly 55 to 64 percent, depending on source and year	The rest

The sources disagree on the share

The Coffea article says arabica is "around 55%" of production, while the Coffee article says "about three-quarters". A web search of secondary sources quoting International Coffee Organization reports gave 55.9 percent (December 2023 report), about 58 percent for coffee year 2024, and about 61 percent in a 2026 report; export-only figures can reach 64 percent. I could not open the ICO reports themselves, so treat "roughly 55 to 64 percent" as a range, not an exact number (check).

Arabica is thought to be a natural hybrid of C. canephora and C. eugenioides. Carl Linnaeus described the genus and its type species, C. arabica, in 1753.

The Journey in Six Steps

Every cup follows the same route. The remaining chapters of the course take each stop in turn.

Step	What happens	Key fact from the sources
1. Pick	Ripe cherries are harvested	Selective hand-picking at peak ripeness, or strip-picking everything at once
2. Process	Fruit is removed from the seed and the seed dried	The dry method is simpler and less labour-intensive; the wet method uses batch fermentation and more water and often gives a milder coffee
3. Roast	Green seeds are heated until they turn brown and aromatic	Roasting proper begins when the bean's internal temperature reaches about 200 °C
4. Grind	Roasted beans are broken into particles	A burr grinder is generally considered better than a blade grinder for most methods
5. Brew	Hot water pulls flavour out of the grounds	Optimal extraction is said to occur between 91 and 96 °C
6. Drink	You taste the result of every earlier choice	Roasting does not change the total caffeine in a bean

Dark roast, same caffeine

The Coffee article notes that light and dark roasts differ in caffeine by only about 0.1 percent. Darker beans expand during roasting, so a scoop of dark roast holds less coffee by weight and therefore a little less caffeine. This is why serious brewers weigh coffee rather than measure it by volume, which is where the next section starts.

Weigh It: Your First Brewing Numbers

Brewing is mostly a ratio of coffee to water. A common starting point for filter coffee is about 1 part coffee to 15 or 16 parts water by weight, and for espresso about 1 part coffee to 2 parts liquid. These ratios come from my own knowledge, not from the pages I read, so treat them as starting points to adjust to taste (check). The script below turns a coffee dose into a water amount, and also does the peaberry arithmetic from the table above. I ran it to get the output shown.

def water_for(dose_g, ratio):
    return dose_g * ratio

for name, dose, ratio in [("Filter (1:16)", 20, 16), ("Filter (1:15)", 20, 15), ("Espresso (1:2)", 18, 2)]:
    print(f"{name}: {dose} g coffee -> {water_for(dose, ratio):.0f} g water")

# Peaberry share: 5-10% of fruits hold one seed
fruits = 1000
for pct in (5, 10):
    one = fruits * pct // 100
    seeds = one * 1 + (fruits - one) * 2
    print(f"{pct}% peaberry: {fruits} fruits -> {seeds} seeds")

# Output
Filter (1:16): 20 g coffee -> 320 g water
Filter (1:15): 20 g coffee -> 300 g water
Espresso (1:2): 18 g coffee -> 36 g water
5% peaberry: 1000 fruits -> 1950 seeds
10% peaberry: 1000 fruits -> 1900 seeds

What the numbers show

Moving from 1:16 to 1:15 saves 20 g of water on a 20 g dose, a small shift you can taste. And because peaberries are only 5 to 10 percent of fruits, 1,000 cherries yield about 1,900 to 1,950 seeds, close to the 2,000 you would expect if every fruit held two.

A Short, Honest History

The popular story of Kaldi, the goatherd who noticed his goats becoming lively after eating the plant, is set in the 9th century. The Coffee article says the story does not appear before 1671 and calls it likely apocryphal; the name Kaldi itself appears to be a 20th-century invention. The same article says there is no confirmed historical or archaeological evidence of coffee being drunk before the 15th century, and that by the late 15th century coffee drinking was well established among Sufi communities in Yemen.

Who Grows It

For 2023 the FAO statistics quoted on Wikipedia give world green coffee production of 11.06 million tonnes, led by Brazil (3.41 million tonnes, 31 percent), then Vietnam (1.96), Indonesia (0.76), Colombia (0.68) and Ethiopia (0.56).

Not Yet Verified, and Sources

Sources. Wikipedia articles Coffea and Coffee, plus one web search about arabica's share of production. The Coffee article is about 251,000 characters long and I read only the first 100,000, so the economics, consumption and specialty-coffee sections were not read.
Conflict. Arabica's share of production differs between the two articles and between secondary sources (see the box above).
Not in the pages read. The brew ratios (1:15, 1:16 and 1:2), robusta's exact origin and the claim that dark roast leaves a scoop with less caffeine by weight beyond what the article states are from my own knowledge or inference (all marked check).
Not tested. I did not brew with these ratios; the script only does arithmetic.

Exercises

Exercise 1

Explain in two or three sentences why "coffee bean" and "coffee cherry" are both slightly misleading names. Then say what a peaberry is and roughly what fraction of fruits are peaberries.

→ Solution

Exercise 2

Using the script, work out the water needed for a 25 g dose at 1:16 and a 15 g dose at 1:15. Change the script so it also prints the total brew weight (coffee plus water) for each line, and run it.

→ Solution

Exercise 3

Fill in a table with the two main species and the three differences you would tell a friend about (taste, caffeine, rough share of world production). Then list the six steps from cherry to cup in order and say which step you think affects flavour most, giving a reason.

→ Solution

Quick Reference

Bean: the seed of the coffee cherry; usually two per fruit
Peaberry: a single-seed fruit, about 5 to 10 percent
Arabica: sweeter, less caffeine; robusta: bitter, fuller body, 40 to 50 percent more caffeine
Six steps: pick, process, roast, grind, brew, drink
Brew water: 91 to 96 °C; roasting begins about 200 °C
Starting ratios: filter about 1:15 to 1:16, espresso about 1:2 (check)

Coming next

Coffee Fundamentals 2 follows the plant to the farm: where coffee grows and why altitude matters.