Green Coffee Specification: Robusta vs Arabica, Screen Size and Moisture

Robusta or Arabica?

The two species behave differently from the tree to the cup, and neither is simply “better”:

Vietnam is the world’s largest Robusta producer, and Robusta makes up most of its crop. For espresso, a Robusta share adds body and crema to an Arabica base; a “bold” blend can be built from either species or both. Treat the blend ratio as a sensory and cost decision, and fix it with a cup reference.

What does screen 13, 16 or 18 mean?

Screen size grades beans by passing them over sieves with round holes. The number is the hole diameter in 64ths of an inch:

A grade such as “screen 18” means that a stated share of the beans — often 90% — stays on the screen 18 sieve; “16/18” describes beans sized between those screens. Write the share and the maximum allowed below the lower screen into the contract, because conventions vary between buyers.

Similar bean sizes can help make roasting more uniform. Screen size can also affect price, but a larger screen does not by itself guarantee higher value. It says nothing about defects, moisture or taste. A screen 18 lot can still fail on all three.

Why is 12.5% the moisture ceiling?

The International Coffee Council’s voluntary quality programme (Resolution 420) sets target standards for exported Arabica and Robusta: moisture from 8% to 12.5%, measured by the ISO 6673 method. It permits exceptions for speciality coffees that traditionally have higher moisture, identified by a specific grade name. These are programme standards, not a universal legal export ban. The reasons for controlling moisture:

• Above the ceiling, moulds can grow in storage and transit, with a risk of ochratoxin A formation and musty flavours.
• Too dry, beans become brittle, lose quality and roast unevenly.

In practice, write a maximum (for example 12.5%) with the method (ISO 6673), and check it at loading and on arrival. Moisture can also be gained in transit: warm cargo moving into cooler climates causes condensation inside the container. Liners, kraft paper linings and desiccants reduce that risk; our export logistics page describes how green coffee bags with inner liners are arranged where specified.

Defects, grade and processing

Grade, processing method and a cup reference complete a green coffee specification beyond screen size and moisture.

• Grade. Grades such as Grade 1 and Grade 2 set limits for black and broken beans, foreign matter and moisture. State the actual limits in the contract, not only the grade name, and agree how the sample is drawn and counted.
• Processing. Most Vietnamese Robusta is natural (dry) processed; washed or wet-polished lots are also produced. Our Arabica is offered as washed, natural or honey processed, confirmed per lot. Processing changes the cup, so name it.
• Cup reference. Approve a cupped sample and keep it as the reference. A cup profile is never guaranteed without cupping the actual lot.
• Certifications. Rainforest Alliance or organic lots may be available depending on the crop. Certificate scope and validity are verified before any certified claim appears in an offer.

What data does an EU buyer need for deforestation rules?

Coffee (HS 0901, green or roasted) is covered by the EU Deforestation Regulation (Regulation (EU) 2023/1115). After the latest revision, large and medium-sized operators apply its main obligations from 30 December 2026, and operators who are natural persons or micro and small enterprises from 30 June 2027. These later dates do not apply generally to downstream operators and traders. The operator first placing the coffee on the EU market files a due diligence statement showing the coffee was produced on land not deforested after 31 December 2020 and in line with the laws of the country of production, which requires geolocation data for the plots of production.

If you import green coffee into the EU, agree now what traceability data the supplier provides with each lot — plot geolocation, farm or cooperative references, harvest period — and in what format. Collecting it after shipment is much harder than collecting it at purchase.

Should a new brand buy green or roasted coffee?

Buy green coffee if you roast and want control of the profile; buy roasted coffee if you want a finished product quickly and prefer the supplier to manage roasting.

Green coffee keeps best when used within about a year of harvest. Roasted coffee starts losing freshness within weeks unless it is well packed. Our private label roasted coffee guide covers roast profiles, bags and valves.

What to put in the RFQ

A green coffee RFQ states the species, origin, screen, moisture, defects, processing and cup reference, plus the packaging and the traceability data your market needs:

• species, origin region and blend if any;
• screen size with the retained share and the tolerance below it;
• maximum moisture and the method (ISO 6673);
• defect limits: black and broken beans, foreign matter;
• processing method and crop year;
• cup reference and the cupping protocol for approval;
• packaging: 60 kg jute bags, 1000 kg jumbo bags, liners;
• certifications required and the traceability data needed for your market;
• samples: pre-shipment and arrival sampling points — see our supplier qualification guide.