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Sorting the Great from the Good — Grading, Milling, and Exporting Specialty Coffee
Once parchment is dried and rested, it’s ready for dry milling. This is the final transformation step before export—where parchment becomes green coffee, and quality control takes on a new level of granularity. Understanding the science and logistics behind grading and export helps you become a more informed roaster and a smarter buyer.
Dry Milling — More Than Just Hulling
Dry milling includes hulling, size grading, density sorting, color sorting, and final bagging. It’s where uniformity, defect control, and physical integrity are verified. At Nordic Approach, we do multiple green analyses—checking moisture (ideally 9–11%), water activity (targeting 0.40 to 0.60), and defect counts according to international standards for specialty.
Why Green Grading Matters
Green grading is the bridge between processing and cupping. It tells us if the coffee was well harvested, sorted, dried, and handled post-harvest. While roasting and brewing techniques can highlight the potential of a coffee, no amount of skill can fix a fundamentally flawed green. Defects can cause off-flavors, uneven roasting, or worse—a complete breakdown in cup quality.
Screen size influences roast consistency and physical appearance, but must always be understood in context. Each producing country has its own grading system, so we use Colombia and Kenya here as illustrative examples. But be aware—from Ethiopia to Honduras to Indonesia, grading standards vary widely, and understanding these local frameworks is crucial to sourcing well.
Screen Size Grading
Screen size is measured in 1/64ths of an inch. In Colombia, coffee is traditionally exported as Excelso or Supremo. Supremo refers to beans screen 17 and up, while Excelso includes 14–17. However, we often request screen 15 up as our standard. This allows producers to include a broader range of high-quality beans, maximizing yield and financial return without compromising cup quality.
In Kenya, grading is more granular and strictly tied to screen size:
- AA: Screen 17/18
- AB: Screen 15/16
- PB: Peaberry
- C: Below screen 14 (we don’t buy these)
We participate in and cup pre-auction outturns in Kenya to select lots based on both screen size and flavor. Well produced and graded AA’s and AB’s might score 87–90+, while a PB lot could have the same high score, offering something more unusual or intense despite its size. The C grades from the same lot often scores lower.
Defect Grading
Defects are categorized into primary and secondary:
- Primary: Full black beans, full sour, fungus-damaged, foreign matter. Just one of these can heavily penalize a lot.
- Secondary: Broken, chipped, immature, partial black, parchment fragments. These are more tolerated but still impact score and roasting performance.
According to SCA green grading protocol, a 350g sample must have no primary defects and a very limited number of secondary defects to qualify as specialty. We log and monitor defect trends at the lot level for specific coffees when we notice irregularities from the given standards, allowing us to trace quality issues back to specific processing or harvest decisions.
Final Checks and Export
After milling, we cup pre-shipment samples again to ensure nothing changed during hulling or bagging. Coffees are packed in 60-70 kg jute bags with GrainPro liners or vacuum bags/boxes to prevent moisture and contamination during shipment. Containers are inspected, sealed, and tracked to the local port (in landlocked countries like Ethiopia, this means Djibouti, for Uganda/Rwanda it’s Mombasa or Dar Es Salam).
Our quality control isn’t about just saying "yes" or "no" to a lot. We aim to work with producers to help improve quality over time. This means cupping feedback, fermentation trials, and selective separation of high-scoring microlots.
By understanding the science and logistics behind grading and export, you can become a better buyer, a more informed roaster, and a stronger partner in the supply chain.
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