By the time a sack of green coffee arrives at a roastery, the beans have already been handled by growers, pickers, processing teams, mill workers, exporters, shipping companies and warehouse staff.
Roasting may be the point where the coffee develops its familiar colour and aroma, but most of the groundwork has already been done. The way the cherries were picked, how the coffee was processed and whether it was dried properly can all affect what happens later in the roaster.
Picking the Coffee
Coffee beans begin life inside coffee cherries. These are picked once they ripen, although the method depends on the farm, the terrain and the amount of labour available.
On some farms, pickers return to the same trees several times and remove only ripe cherries. This is common where the producer is aiming for a higher-quality lot and wants tighter control over ripeness.
Other farms use strip picking, where most of the cherries are removed at once. Mechanical harvesters may also be used on flatter, larger farms. These methods are quicker, but they can collect a mixture of ripe, underripe and overripe fruit, which then needs to be sorted.
Coffee cherries start to change soon after picking, so they cannot be left sitting around indefinitely. They need to reach a processing area while they are still in good condition.
Removing the Fruit
There is more than one way to separate the beans from the coffee cherry.
With washed coffee, the skin and most of the fruit are removed fairly soon after picking. The beans are fermented to break down the sticky mucilage left around them, then washed and prepared for drying.
Natural coffee is dried inside the whole cherry. The fruit stays around the beans for much longer, which can add sweetness, body and more pronounced fruit flavours. It also leaves more room for things to go wrong if the cherries dry unevenly or begin to ferment in an uncontrolled way.
Honey and pulped natural coffees sit somewhere between the two. The outer skin is removed, but some of the fruit remains on the beans while they dry.
The method listed on a coffee is useful, but it does not tell the whole story. A well-managed natural can be clean and balanced, while a badly handled washed coffee can still have defects. The standard of the work matters as much as the name of the process.
Drying the Coffee
After processing, the coffee needs to be dried before it can be stored safely.
Depending on the origin, this may happen on patios, raised beds or in mechanical dryers. Coffee laid out in the open has to be turned regularly so that it dries evenly. It may also need to be covered during rain or moved out of strong midday heat.
This part of the process can take days or weeks. Drying the coffee too slowly can encourage mould and unwanted fermentation. Drying it too quickly can leave the moisture inside the bean uneven.
Weather has a large influence. A producer working through a period of heavy rain will face a very different job from one drying coffee in warm, settled conditions.
Once the coffee reaches the required moisture level, it is often rested before milling. Washed coffees are normally stored in their parchment, the dry protective layer that still surrounds the green bean.
Sorting and Grading
The coffee next moves to a dry mill.
Here, the parchment is removed from washed coffee. For naturally processed coffee, the dried cherry material is hulled away. What remains is the green coffee bean that roasters recognise.
The beans may then pass through several sorting machines. Some separate them by size. Others use weight or density to remove light, poorly developed beans. Colour sorters can pick out beans that look pale, dark or otherwise unusual.
Some coffees are also sorted by hand, particularly where the buyer or exporter has requested a tighter defect standard.
The grading terms used on coffee listings can vary from one country to another. AA may refer to bean size in one origin, while terms such as SHB or SHG generally relate to the altitude at which the coffee was grown.
These labels are useful, but they are not a guarantee that a coffee will taste good or suit a particular roaster.
Sampling Before Shipment
Before a larger lot is purchased, a sample is normally assessed.
The green beans can be checked for visible defects, moisture, size and general uniformity. A small amount is then roasted and cupped so the buyer can assess the flavour.
This is where problems that are not obvious by eye may show themselves. A coffee can look fairly clean but still have a mouldy, earthy or fermented taste. The opposite can also be true. A lot that is not perfectly uniform in appearance may still produce an excellent cup.
Samples may be checked more than once. A pre-shipment sample allows the buyer to approve the coffee before it leaves origin. Another sample may be taken after arrival to confirm that the delivered coffee matches what was agreed.
Exporting and Shipping the Coffee
Once the lot has been approved, it is packed for export.
Jute sacks are still widely used, often with a sealed liner inside to give the coffee more protection from moisture and outside smells. Larger commercial lots may be shipped in bulk liners rather than individual sacks.
The coffee then has to travel from the mill to the port, clear export checks and wait for a suitable shipment. It will usually spend several weeks at sea before reaching the UK.
Shipping is not simply dead time. Heat, humidity and condensation inside a container can affect coffee that has not been packed or handled properly. Delays can also extend the amount of time the coffee spends in transit.
After the container arrives, the coffee clears customs and moves into a warehouse. It may be stored there as a full imported lot before being sold on in sacks, smaller bags or mixed orders.
When the Roaster Finally Receives It
The roaster is not starting with a blank canvas.
The bean’s density, moisture, processing method, age and condition will all affect how it responds to heat. Two coffees may have similar tasting notes on paper but behave very differently once roasting begins.
A sample roast gives the roaster a first look at how quickly the coffee takes on heat, when it reaches first crack and how much development it may need. Profiles can then be adjusted before the coffee moves into regular production.
Good roasting can develop the qualities already present in the beans. It cannot undo poor picking, mould, uneven drying or storage damage.
That is why the information supplied with green coffee matters. Origin, crop, processing method and physical measurements are not just background details. They help the roaster understand what has happened to the coffee before it reached the machine and what it may need once roasting begins.