Most green coffee grading systems were built around large, uniform, washed beans. Applied to Yemen they produce nonsense: a superb Hirazi lot can look, on paper, like a low grade. Buying this origin well means knowing which numbers carry information and which do not.
Screen size — the least useful number
Yemeni beans typically fall between screen 13 and 17, and a single lot usually spans several sizes because it comes from mixed landraces on mixed terraces. Small does not mean poor here. What size does affect is roasting: a wide size spread needs a gentler ramp so the small beans do not scorch while the large ones are still developing.
Defect count — the most useful
Because drying happens in the open, defects are the real quality axis: over-fermented beans, insect damage, stones and sticks from terrace drying, and under-dried cherries. Careful cooperative sorting is the single biggest difference between an ordinary lot and an excellent one. Ask for a defect count on a stated sample size, not a grade letter.
Moisture and water activity
| Measure | Target | Why it matters |
|---|---|---|
| Moisture content | 10 – 12 % | Below 9 % the coffee has faded; above 12.5 % it will not keep |
| Water activity | 0.55 – 0.62 aw | Predicts storage life better than moisture alone |
| Density | High for the altitude | Confirms the altitude claim and guides the roast |
| Crop year | Stated explicitly | Yemeni lots are often held; age changes the cup |
Cupping
We cup every lot before offering it, and we cup it again before it ships. A score is useful shorthand but the notes matter more: a lot at 85 with clean fruit and a lot at 85 with a hard ferment edge are different purchases even at the same number. Where a lot has been formally scored we say by whom.
Questions worth asking any supplier
- What crop year is this, precisely?
- Which region, and which village or collection point?
- What is the moisture content and water activity today, not at purchase?
- How many defects per 300 g, and of what kind?
- Was it dried on rooftops, patios or raised beds?
- How has it been stored, and in what packaging?