Natural, Honey, Washed and Beyond: How Vietnamese Green Coffee Is Processed

Processing shapes a Vietnamese green coffee lot more than most first-time buyers expect. The same Robusta cherry from a Dak Lak farm can end up as a heavy, earthy commodity bean or as a clean, chocolate-driven fine Robusta, depending on how it was picked, fermented, dried and sorted. For Arabica from Cau Dat or Son La, processing is often the main difference between an 80 point lot and an 84 point lot.

Vietnam exports roughly 1.5 to 1.8 million tonnes of green coffee a year, around 95% of it Robusta. For decades almost all of that volume was dried as whole cherry on patios. That is still the backbone of the trade, but buyers can now source washed, honey, wet polished and fermented lots, from full containers down to a few hundred kilograms. This guide explains each method as it is practised in Vietnam, its effect on cup and spec and what to write in an order so the lot you receive matches the sample you approved.

Why processing belongs in the spec

Processing affects five things a buyer cares about:

• Cup profile: sweetness, body, acidity and the presence of ferment, earthy or woody notes.
• Moisture stability: how evenly the beans dried and how well they hold moisture during storage and shipping.
• Defect profile: black, brown, sour and moldy beans are often processing defects, not farm defects.
• Uniformity: color and density spread across the lot, which affects roast evenness.
• Price and availability: washed and honey Robusta carry premiums over natural, and fermented micro-lots are priced outright.

A process name on a contract without a definition leaves room for interpretation. “Honey” or “semi-washed” can mean different things on different farms, so the goal is to attach measurable limits to whatever label is used. If you are new to Vietnamese grades, the green coffee grade reference sets out the screen, moisture and defect limits that processing has to deliver.

The main processing methods used in Vietnam

Natural (dry) processing

Whole cherries are spread to dry in the sun for roughly two to four weeks, then the dried husk is removed in a huller. This is how most Vietnamese Robusta is processed. The method is low cost and needs little water, which suits the dry season in the Central Highlands, where harvest runs roughly from November to January.

The weak point is picking. Commercial Robusta is often strip picked, so green, ripe and overripe cherries dry together. Unripe cherries produce pale, astringent beans, overripe cherries can over-ferment and thick layers on the patio dry unevenly. The result is the earthy, woody, sometimes rubbery cup many roasters associate with Vietnamese Robusta.

Selective picked naturals are different. When farms pick mostly ripe red cherry (a common target is 90% ripe or more), dry in thin layers and turn the cherries often, natural Robusta can show dark chocolate, dried fruit and a heavy, syrupy body. Many fine Robusta lots are naturals made this way.

Honey (pulped natural)

The skin is removed with a pulper, but some or all of the sticky mucilage stays on the parchment during drying. Farms describe yellow, red or black honey depending on how much mucilage is left and how slowly the coffee dries. Honey processing is used on some Cau Dat Arabica farms and on a growing number of fine Robusta farms.

Honey lots usually gain sweetness and body compared with washed coffee from the same farm. The risk is drying: sticky parchment clumps and can mold if layers are thick or the weather turns humid, so honey lots need raised beds or careful mechanical drying.

Washed (fully washed)

Cherries are pulped, the parchment ferments in tanks to break down the mucilage, then it is washed with clean water and dried. In the cooler highlands, fermentation commonly takes 12 to 48 hours depending on temperature. Washed processing is the standard for Arabica in Lam Dong and Son La.

Washed Robusta is less common but well established. It removes much of the earthy character of naturals and produces a cleaner, lighter cup with more visible acidity. Vietnamese exporters often list “Robusta S18 washed” as a separate grade.

Semi-washed and wet polished Robusta

Semi-washed coffee is pulped and then the mucilage is removed mechanically with a demucilager instead of a fermentation tank. It sits between washed and honey in cup style and water use.

“Wet polished” is a Vietnamese trade term that is used loosely. It usually describes Robusta that has been hulled and then polished with a small amount of water to remove silverskin and surface dust, then re-dried. It improves appearance and can make the cup slightly cleaner. Because it adds a wetting step after the beans are dry, ask how the beans were re-dried and hold the exporter to a final moisture limit.

Experimental fermentation

A small but active group of Vietnamese producers now runs anaerobic fermentation (sealed tanks or bags where oxygen is excluded), carbonic maceration with whole cherries, yeast inoculated fermentation and extended fermentation trials. These lots are typically between 100 kg and a few tonnes and are aimed at specialty roasters.

Well-controlled lots show winey, tropical fruit or liqueur notes, and fine Robusta in particular can change character dramatically. Poorly controlled lots taste vinegary or phenolic. Batch-to-batch consistency is the main risk.

Method comparison for buyers

Method	Where used in Vietnam	Typical cup direction	Main spec risk to control	Relative volume
Natural (strip picked)	Robusta, all Central Highlands provinces	Earthy, woody, heavy body	Black and sour beans, uneven moisture	Very large
Natural (selective picked)	Fine Robusta farms, some Arabica	Chocolate, dried fruit, syrupy body	Over-fermentation, drying evenness	Small to medium
Honey	Cau Dat Arabica, fine Robusta	Sweeter, rounder body	Mold risk during drying	Small
Washed	Arabica in Lam Dong and Son La, some Robusta	Clean, brighter acidity	Fermentation control, water quality	Medium for Arabica, small for Robusta
Semi-washed	Robusta and Arabica mills	Between washed and honey	Mechanical damage in demucilager	Small
Wet polished	Commercial and export Robusta	Slightly cleaner natural	Moisture after re-drying	Medium
Anaerobic or yeast	Specialty farms and micro-lots	Fruit, wine, liqueur	Consistency, off-ferment notes	Very small

Drying: patios, raised beds and mechanical dryers

Drying is where many Vietnamese lots gain or lose quality.

Concrete patios and tarpaulins are the standard for commercial Robusta. They are cheap and fast in the dry season. Problems come from thick layers, infrequent raking, contact with soil or roadside dust and sudden rain. Patio dried lots can be sound, but the spread of moisture between individual beans tends to be wider.

Raised beds (sometimes called African beds) allow air to circulate under the coffee, dry more slowly and more evenly and keep the beans off the ground. Most specialty Arabica and fine Robusta lots are dried this way, often under shade nets or in polytunnels on Cau Dat farms.

Mechanical dryers, typically rotary drums or static box dryers fuelled by husk or wood, make drying independent of the weather and are common at larger processing stations. They work well when temperature is controlled. Excessive heat can leave the cup flat or baked, so for specialty lots it is reasonable to ask whether bean temperature stays below roughly 40 to 45 degrees Celsius. Many mills combine a few days on patios or beds with a finishing stage in a mechanical dryer.

After drying, dried cherry or parchment is usually rested for several weeks before hulling so that moisture evens out inside and between beans. Target moisture at export is typically 10.5% to 12% for specialty and up to 12.5% for Robusta grades, with water activity guidelines of about 0.55 to 0.65 aw.

Hulling, sorting and grading

Once rested, the coffee moves through a dry mill:

1. Hulling removes the dried husk (naturals) or parchment (washed and honey).
2. Polishing, optional, removes silverskin; this is where wet polishing happens.
3. Size grading on screens separates beans by size, for example screen 18 (7.14 mm), screen 16 and screen 13.
4. Density sorting on gravity tables removes light, underdeveloped and insect damaged beans.
5. Color sorting with optical sorters removes black, brown, sour and discolored beans. Many export lots are color sorted twice.
6. Hand picking is added for specialty lots to reach low full defect counts.

Each step narrows the spread of the lot and lowers the defect count per 300 g sample. For a detailed explanation of how screen sizes and defect counts map to Vietnamese grades, see Vietnam Robusta grades and screen sizes explained.

What to specify in an order

A practical processing spec for a Vietnamese lot covers:

• Process name plus a one-line definition, for example “honey, pulped with mucilage left on, dried on raised beds”.
• Picking standard, such as ripe cherry share at intake.
• Drying method and, for specialty, maximum dryer temperature.
• Moisture limit, for example 12.5% maximum for Robusta S16 or S18 and 12% for specialty Arabica, plus a target water activity if you use it.
• Screen size, for example 90% or more on screen 18.
• Defects per 300 g, using TCVN 4193:2014 or SCA counting.
• Sorting, for example double color sorted plus hand picked.
• Crop year and harvest window.
• Lot size and packaging, such as jute with GrainPro liner or vacuum packs for micro-lots.
• Sample approval: offer sample, pre-shipment sample and the tolerance between them.

For fermented lots, add the fermentation type, duration and temperature range, and ask whether the producer records pH or Brix. For fine Robusta, a cupping score target (for example 80 points or above on a fine Robusta or SCA-style form) is useful. The guide to fine Robusta and Vietnamese Arabica exporters covers how those lots are offered.

Sampling across processes

The most useful sampling exercise is to request two or three processes from the same farm or station, for example natural, honey and washed Robusta from one crop. Cupping them side by side shows what the process contributes, separate from the terroir and variety. Typical sample sizes are 300 to 500 g per lot, enough for moisture testing, a defect count and two or three cupping sessions. Always keep a portion of the approved sample to compare with the pre-shipment sample.

Send your processing spec

If you know the process, grade and volume you want, send your spec through the RFQ page. Include process, screen, moisture, defect limits, lot size and destination. You will receive a reply within 24 business hours, and the spec is matched with up to 3 Vietnamese exporters, processors or farms that work with that process, who then quote and deal with you directly. The service is free for buyers and an NDA can be signed on request.