Green coffee is graded physically before it is ever tasted. A sample is spread out and examined, and damaged or abnormal seeds are counted. Defects include black and sour beans, which come from over-ripe, diseased or badly fermented fruit; insect damage; unripe or immature beans; broken and chipped beans; shells; and foreign matter such as stones and sticks.
The Specialty Coffee Association's long-used green grading protocol works on a 350-gram sample and divides defects into two categories by severity. Under it, a coffee is specialty grade only with no Category 1 defects and no more than five Category 2 defects. Many producing countries have their own national systems with different counts and names.
Defect counting tells you how carefully a coffee was picked, processed and sorted. It does not tell you whether the coffee tastes interesting. A defect-free coffee can be dull, which is why physical grading is always paired with tasting.
Beans are sorted by size using perforated screens, numbered by the diameter of the holes in sixty-fourths of an inch: a screen 17 has holes seventeen sixty-fourths of an inch across. Size matters to a roaster because beans of mixed sizes roast unevenly.
Many of the grade names that appear on bags are size or altitude classes from one country's system. Kenya's AA and AB are sizes. Colombia's Supremo and Excelso are sizes. In several Central American countries, terms such as Strictly Hard Bean describe the altitude at which the coffee was grown, on the reasoning that higher-grown beans are denser.
None of these is a flavour score, and they are not comparable between countries. A Kenya AB can out-taste a Kenya AA. The names are worth learning precisely so that they stop sounding like a quality ranking.
Green coffee is traded at a moisture content of roughly ten to twelve per cent. Wetter than that risks mould; much drier and the coffee tastes flat and ages quickly. Buyers measure moisture and often water activity, which describes how available that moisture is to microbes and chemical reactions, and density.
Green coffee is far more stable than roasted coffee but it is not inert. It exchanges moisture with the air and slowly loses its aromatic potential. Traditional jute sacks protect it very little; many specialty lots are now shipped in sealed, low-permeability liners inside the sack, or vacuum-packed, which slows ageing considerably. Heat and humidity in transit and in warehouses do most of the damage.
A lot is a quantity of coffee kept separate and sold as one thing. At one end is a regional blend built for consistency from many sources. In the middle are lots from one cooperative, washing station or estate. At the other end is a micro-lot: a small quantity from one plot, one variety, one day's picking or one fermentation, kept apart because it is distinctive.
Separation costs money at every stage, since each lot needs its own tank, drying bed, bag and paperwork. That cost, as much as the cup, is what a micro-lot's price reflects. Traceability records which coffee is which along the way. It makes quality claims checkable and lets a premium reach the people who earned it. It is not, by itself, a claim about flavour or ethics.
Your task. Enter how much coffee you use and the bag size you buy, and find how long one bag lasts you. Compare that with the weeks roasted coffee stays at its best, and then with the many months green coffee keeps.
What to notice. Roasting starts a short clock; green coffee runs on a long one. That gap is why roasters hold green stock and roast to order, and why a harvest date matters as well as a roast date.
Exercise: Reading a bag as a buyer would
Objective. Work out what a coffee label actually tells you, and what it leaves out.
You will need
Two or three bags of coffee, or their product pages
Something to write on
Keep the same
Use the same list of questions for every bag
Procedure
For each bag, look for: country, region, farm or washing station or cooperative, variety, altitude, processing method, harvest or crop year, roast date.
Mark each item as stated, vague or absent.
Note any grade term — AA, Supremo, SHB, Grade 1 — and look up which country's system it belongs to.
Note any claim with no definition behind it, such as 'premium' or 'gourmet'.
What to notice
Which bag could you trace furthest back towards a farm?
Which grade terms describe size, which altitude, and which defects?
Is there a roast date, or only a best-before date?
Reading what you found
Traceability is not quality, but it is the precondition for knowing anything about quality. A grade term tells you about one country's sorting rules, most often bean size, and is not comparable across countries. A missing roast date tells you the seller does not expect you to ask.
What this cannot show
A label is a claim. This exercise checks what is claimed, not whether it is true.
Small producers are sometimes unnamed for commercial reasons rather than because the coffee is untraceable.
A protocol for you to run. CoffeeHQ has not run it and reports no result from it.
A roaster buys a lot sold as the top national grade. It is clean and uniform, with almost no defects. Roasted and tasted, it is pleasant and flat, with nothing to distinguish it.
Reasoning it out
The grade reflects size and defect count, both of which are excellent.
Neither measures aromatic quality.
A flat cup from clean coffee can mean an ordinary variety, low altitude, an old crop or coffee that aged in a hot warehouse.
The harvest date and the storage history are the things to ask about.
What to do
The grade was accurate and answered a different question. To judge flavour the roaster needed a tasted sample, the crop year and the moisture reading, not the grade name. This is the argument for tasting before buying.
SCA green coffee grading protocol and defect classification — Specialty Coffee Association
Coffee Quality Institute Q Grader / cupping standards — Coffee Quality Institute (CQI)
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