Green Coffee Selection and Export Preparation
Sources: El Arte del Café by Sébastien Racineux & Chung-Leng Tran (Lunwerg, 2017); The Coffee Roaster’s Companion by Scott Rao (2014)
After drying, green coffee still contains impurities and must be cleaned, selected, and packaged before export. This stage — dry milling (beneficio seco) — is the final quality control step before coffee leaves the producing country. (source: El Arte del Café)
Dry Mill (Beneficio Seco)
Dried coffee is transported to a dry mill for cleaning and selection.
Cleaning
- Aspiration and sieving: Removes debris, small stones, metal fragments, dust, and leaves.
- Husking (descascarillado): For natural and pulped natural coffees, a husking machine crushes the dried cherries against metal walls, separating dry skin and pulp from the beans. Compressed air removes the loosened husk.
- For washed coffee: A machine removes the endocarp (parchment). Beans are then cleaned to remove the silver film below the endocarp.
Selection (4 Stages)
Stage 1 — Density sorting
Mechanical or manual. Dense beans (well-developed, mature) are separated from light beans (defective, immature). Methods: air current (heavy beans fall straight; light beans are blown aside) or water flotation (dense sink, defective float).
Stage 2 — Size calibration
Beans pass through graded screens with openings of different diameters. Sorted into size categories. Uniform size improves roast consistency (smaller beans roast faster than larger ones in the same batch).
Stage 3 — Colour sorting (automated)
Beans travel on conveyor belts equipped with colour detectors:
- Black or very dark = fermented beans
- Pale or white = immature/hollow beans
When a defective bean is detected, a jet of air discards it.
Stage 4 — Manual finishing
Final visual sort, typically performed by women seated alongside the conveyor belt. Catches anything automated sorting missed.
Defective Beans
Defective beans are not wasted. A market exists for off-grade lots: they feed mass-market espresso blends, instant coffee production, and commodity markets. (source: El Arte del Café)
Export Packaging
Three main packaging formats, with different preservation profiles:
Jute sacks (Sacos de tela de yute)
- Traditional packaging, 60–70 kg
- Economical, solid, durable
- No special atmosphere control
- Part of the folklore and visual identity of the trade
- Adequate for commodity-grade coffee; less ideal for preserving specialty aromatics over long transport
Vacuum packs (Envases al vacío)
- Appeared recently for premium specialty lots
- 20–35 kg; some microlot importers use <10 kg packs
- Correct preservation; some volatile aromatics lost during the vacuuming process
- No zipper/reseal
- Up to 3 months
GrainPro® bags
- Multilayer plastic bags designed to preserve aromatic potential of green coffee, seeds, and grains over extended periods
- Best option for maintaining green coffee quality during long transit
- Used by quality-focused exporters for specialty and microlot coffee
Moisture Content and Water Activity
Two key measurements determine green coffee quality and storage stability:
Moisture content: ideal 10.5–11.5%. Below this range: hay/straw flavors, beans roast too fast. Above 12%: mold risk, grassy cup. (source: The Coffee Roaster’s Companion by Scott Rao (2014))
Water activity (aw): measures how easily moisture migrates in/out of the bean. Ideal 0.53–0.59. Measure before sealing in hermetic packaging (GrainPro, vacuum) to prevent mold development. (source: The Coffee Roaster’s Companion by Scott Rao (2014))
Measuring both values for every lot and sharing them with roaster customers is part of a premium traceability offering. See Green Coffee Storage for full storage guidance.
Freshness and Seasonality of Green Coffee
Green coffee behaves as a seasonal fresh product, even though it travels long distances and undergoes multiple steps between harvest and the roaster.
Past crop: Green beans from an old harvest. Lipids degrade; humidity index (~11%) becomes variable. The coffee develops a woody taste, diminished acidity, and aromas reminiscent of burlap sacks (“old crop” profile). (source: El Arte del Café)
A coffee can turn “old crop” not only from age but from:
- Poor drying in the producing country
- Inadequate storage conditions (humidity, temperature)
- Long transport times
- Storage delays before roasting
Harvest calendar for El Salvador: November–March (main harvest).
Specialty roasters treat green coffee seasonality similarly to how chefs treat seasonal ingredients — working with harvest windows and “seasonal coffees.” Coffee packages from artisan roasters should display the harvest year; absence of this information is a warning sign (see Roasting).
Traceability
Full traceability links each roasted lot back to:
- Country and region of origin
- Farm or washing station
- Producer
- Harvest year
- Processing method
For Kaiserblick, traceability is a core value proposition in green coffee export. The book notes that El Salvador has good traceability infrastructure and that the Consejo Salvadoreño del Café promotes this. Full lot-level traceability (to individual farm parcels) remains a differentiator in the specialty market. (source: El Arte del Café)