Processing

Dry Processing

This is the operational counterpart to the [natural coffee](/coffee-knowledge/natural-coffee/) page. Dry processing looks simpler than wet processing and is harder to do well, because the process runs for weeks and every hour of it is an opportunity for something to go wrong.

Last reviewed July 20263 min read

Quick answer

Dry processing dries whole cherry to around 11% moisture over roughly two to four weeks, then hulls the skin, dried pulp and parchment off in a single operation. The controls that matter are cherry selection at reception, bed loading depth, and turning frequency — particularly in the first 72 hours, when the fruit is wettest and most vulnerable.

Reception: the only sorting step that works

In wet processing, several downstream steps remove defective material. In dry processing there is essentially one: reception. Once cherry is on the bed, an under-ripe stays in the lot until the dry mill, by which point its contribution to the cup is already made.

Floatation removes hollow, insect-damaged and dried cherry.
Hand sorting on the reception table removes unders and over-ripes that float ambiguously.
Delivery discipline matters: cherry that sat in a sack overnight has already begun fermenting inside the fruit.

Cherry reception, floatation and sorting
Whole cherry spread thinly on beds
Frequent turning, shaded at peak sun
Drying over 2–4 weeks
Rest in dried cherry
Hulling — skin, pulp and parchment removed together
Screening and density sorting
Colour sorting and final preparation

The dry-processing sequence.

Bed loading and turning

Cherry goes onto raised beds — mesh tables raised off the ground so air moves underneath. Initial layer depth is the single most consequential decision. Too deep and the interior of the layer stays wet, warm and anaerobic; that is where mould and over-fermentation start.

Typical drying management by stage
Stage	Approximate moisture	Layer depth	Turning
Days 1–3	55% → 30%	Very thin, single layer	Very frequent; hourly in some stations
Days 4–10	30% → 18%	Can be increased gradually	Several times daily
Days 11–20	18% → 12%	Deeper permissible	Twice or more daily
Final days	12% → 11%	As above	Continue; watch for over-drying

Indicative only. Actual timing depends on altitude, humidity, cloud cover and bed loading. Warm humid conditions extend the risk window considerably.

Illustrative only. Actual curves depend on bed loading, ambient humidity, altitude and turning frequency. The flattening tail is where over-drying risk sits — most damage happens after the coffee looks finished.

The curve flattens well before drying is finished — which is where over-drying happens.

Failure modes

What goes wrong in dry processing
Fault	Cause	Cup signature	Visible in green?
Mould	Deep layers, insufficient turning, humid weather	Mouldy, musty, earthy	Sometimes; often not
Over-fermentation	Wet cherry held too long before spreading	Sour, fermented, alcoholic	No
Phenolic taint	Prolonged wet-warm conditions in the layer	Medicinal, iodine, plastic	No
Over-drying	Left on beds after target reached	Woody, papery, flat; brittle beans	Sometimes — pale, brittle
Uneven drying	Poor turning, inconsistent bed depth	Inconsistent cups within one lot	Sometimes — mottled colour

Why cup approval is mandatory for naturals

Look at the "visible in green" column. The most damaging dry-processing faults leave little or no trace a screen and defect analysis will catch. This is the concrete reason a natural lot must be approved on the cup, from a sample that genuinely represents the parcel.

Resting and hulling

Dried cherry is stored before hulling — typically in a ventilated warehouse, protected from moisture ingress. Storage here still affects the final cup, and rushing to hull immediately after drying is a false economy.

Hulling removes the dried skin, pulp and parchment in one operation. It is more abrasive than hulling parchment, and the equipment settings matter: over-aggressive hulling chips and cracks the bean, creating both a defect class and an entry route for moisture and mould in storage.

Dry milling and grading

After hulling, dry-processed coffee goes through the same sequence as washed coffee — pre-cleaning, screen separation, gravity table, colour sorting — but generally requires more of it, because dry processing produces a wider spread of bean colour and density. Colour sorting in particular does heavy lifting on naturals.

Hulling — parchment or dried cherry removed
Pre-cleaning — stones, husk and foreign matter
Screen separation by bean width
Density separation on the gravity table
Colour sorting, optical and manual
Grade assembly and bagging

Dry milling: the same sequence for both processes, run harder for naturals.

Natural lots, specified properly

We will confirm the drying regime and station where the information exists, and describe the parcel as it is rather than as its best bag.

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Frequently asked questions

How long does dry processing take?

Typically two to four weeks from spreading to target moisture, depending on altitude, humidity, cloud cover and bed loading. Higher-altitude and more humid conditions extend it, and a longer drying window means a longer period of exposure to mould risk.

What are raised beds and why are they used?

Mesh drying tables raised off the ground so air can move beneath the coffee as well as over it. They dry more evenly than a patio, keep the coffee clear of ground moisture and soil contamination, and make turning easier. They are standard across East Africa.

Why do naturals need more colour sorting?

Because drying whole cherry produces a wider spread of bean colour and density than drying parchment. Optical sorting is the practical tool for pulling out the discoloured and over-fermented beans that the screens and gravity table leave in.

Can over-dried coffee be identified before roasting?

Partly. Over-dried beans are often paler and noticeably brittle, and moisture and water activity readings will be low. But the cup consequence — woody, papery, flat — is confirmed on the cupping table, not in the green analysis.

Tell us the coffee you need

Lots can be specified by origin, region, process, grade, screen, moisture, defect tolerance, crop year and packaging. Send what you know and we will confirm what each origin realistically supports.