A cup of coffee is the end of a chain that started, on average, about eight months earlier on a tree somewhere between 1,500 and 2,100 metres above sea level. Twelve people touched it before it touched you. Each of them could have ruined it.

Here is the whole chain. Drink the next cup with this in mind.

1. Picking

Coffee grows on a tree as a small red, yellow, or pink cherry, depending on the cultivar. A trained picker walks the rows and selectively harvests only the ripe cherries, leaving the green ones to mature for the next pass. A great farm picks the same trees four or five times over a season.

A bad farm strip-picks. Workers grab everything from the branch at once. Ripe, unripe, overripe, dry. The lot becomes a mess of different sugar contents and different fermentation tendencies. No washing station can fully fix it.

The first decision in the quality chain is whether the people on the slope are paid to pick selectively or paid by weight. If they are paid by weight, they will strip-pick to fill the bag faster. If they are paid per kilogram of ripe cherry, they will work slower and pick better. The economics of the bag in your kitchen start here.

2. Sorting at the wet mill

Within hours of picking, the cherries are delivered to a wet mill, also called a washing station or factory. They are tipped into a tank of water. Ripe cherries sink. Unripe cherries, dry husks, leaves, and over-fermented fruit float. The floaters are skimmed off. The sinkers move forward.

A good washing station then does a second sort by hand. People stand at a moving belt and pick out anything that should not be there. Stones, sticks, bad cherries. The slower the belt, the cleaner the lot.

3. Pulping

A machine called a pulper removes the cherry's red outer skin and most of the fruit pulp, leaving the parchment-covered bean. This has to happen within twenty-four hours of picking. If it doesn't, the fruit starts to ferment on the cherry, which means the fermentation starts wrong, and the cup loses cleanness forever.

This is one of the steps where speed matters more than skill. A skilled mill can pulp a tonne of cherry in an hour without crushing the bean. A bad mill bruises and breaks the seed, opening it to defects.

4. Fermentation

The pulped beans are dropped into a tank. They still have a layer of sticky mucilage clinging to them. Bacteria and yeast in the tank, naturally present or sometimes deliberately introduced, eat through that mucilage over twelve to forty-eight hours.

The fermentation is the alchemy step. Done right, it develops the acids, sugars and aromatic precursors that will become the cup. Done wrong, it produces off-flavours: vinegary, oniony, baggy, fermented in the bad sense. The window between "done right" and "done wrong" can be six hours.

Kenya, uniquely, runs a double fermentation. The beans ferment, get washed, then go back into clean water for a second twelve to twenty-four hour soak. This re-soak is the secret handshake of Kenyan washed coffee. It is water-expensive. It produces the clarity Kenyan buyers fly across the world for.

5. Washing and grading

The fermented beans are washed in clean water to remove the last of the mucilage. As they move through wash channels, they are sorted by density. Denser, heavier beans (which are usually better-developed) sink to the bottom of the channels. Lighter beans are skimmed off the top. The dense fraction continues forward. The light fraction usually becomes a lower grade.

6. Drying

The wet parchment beans are spread on raised African beds. These are mesh tables, about waist high, designed to let air circulate around the bean from all sides. Workers turn the beans by hand every few hours. The beans dry slowly, over fourteen to twenty days, until their internal moisture is around eleven percent.

Slow drying is essential. Fast drying, on tarmac or in mechanical dryers, traps moisture in the centre of the bean. Months later, when the coffee is roasted, that moisture cooks differently from the dry outer shell, and you get baked, hollow flavours. You cannot fix this at the roastery. The drying decides.

7. Resting

Once the beans hit eleven percent moisture, they are bagged in parchment and rested. For four to eight weeks. During this rest, the moisture inside the bean equilibrates and the flavours stabilise. A coffee that is shipped too soon after drying tastes grassy and unfinished. A coffee that is rested well tastes like itself.

8. Milling

The parchment is removed by mechanical hulling. The exposed green bean is then graded by size, density, and colour. Defects are picked out, often by hand. Several hands pass over the same lot to catch black beans, broken beans, insect-damaged beans, foreign objects. A high-grade Kenyan lot can be eyeballed four times before it ships.

9. The auction or the direct sale

In Kenya, most lots historically pass through the Nairobi Coffee Exchange auction. Sample roasts are sent to buyers, who cup, score, bid. The winning buyer takes the lot. The producer is paid through the cooperative or estate.

A growing share of specialty coffee now skips the auction and is sold directly from the producer to a roaster who has visited the farm. We do most of our buying that way. The producer earns more. The roaster has a relationship. Both sides know each other.

10. Export

The green coffee is shipped, usually in jute bags inside a sealed container. From Mombasa it takes four to six weeks to reach Europe, three to four to reach Australia, six to eight to reach the United States. The temperature in the container matters. Too hot for too long and the coffee ages prematurely, losing the brightness it took the whole chain to build.

11. Roasting

A roaster takes the green coffee and applies heat to it. A roast lasts about ten to fourteen minutes for a small-batch specialty profile. Inside that window, hundreds of chemical reactions happen: water evaporates, sugars caramelise, acids develop and then degrade, aromatic compounds form. The roaster is making real-time decisions about temperature, air flow, and time, trying to land on a profile that brings out the best of what the green coffee has to offer.

A great roast on a great coffee is a beautiful thing. A great roast on a bad coffee is still a bad cup. A bad roast on a great coffee is a tragedy. The chain only works if every link holds.

The roasted beans are bagged with a one-way valve, stamped with a roast date, and shipped to the cafe or the home buyer. The clock starts. Roasted coffee is at its best between four days and four weeks off the roast date. After eight weeks, you are drinking stale coffee, no matter how good the bag.

12. Brewing

You. With your kettle, your grinder, your filter, your scale (you should have a scale), and your eleven seconds of attention.

The brewer is the last person in the chain. Brewing decides whether the entire eight-month effort lands or fails. Grind too coarse, the coffee tastes thin and sour. Grind too fine, it tastes bitter and harsh. Water too hot, you scald. Water too cold, you underextract. Water with too many minerals tastes flat. Water with too few minerals tastes empty.

The home brewer who pays attention to four variables (dose, grind, water temperature, brew time) will get more out of a five-dollar bag of beans than a careless brewer gets out of a twenty-dollar bag.

What this changes about how you drink

A few things.

You will pay more for coffee. Because you now know what twelve people had to do to make it not be terrible. The supermarket tin no longer reads as a bargain. It reads as a story you do not know.

You will buy from people who can tell you the story. Roasters, cafes, and importers who can name the cooperative, the harvest, the cultivar, the picker if you ask. If they cannot tell you, the coffee is anonymous. Anonymous coffee is, almost always, coffee where someone in the chain cut a corner.

You will brew with more respect. Because you know what was at stake.

You will, occasionally, drink a great cup. And you will know that it is the rare survivor of twelve steps where it could have been ruined, and that not ruining it took the careful work of twelve different people you will never meet, on a slope you will probably never visit, for a wage that is almost certainly less than your cup cost.

That is the chain. Drink the next cup with it in mind.

Shabaya Limited

From cherry to cup: what really happens to your coffee