Drying systems for tea, coffee and cocoa
Smoke taint is a rejection, not a discount.
Tea, coffee and cocoa are dried after a biological step — withering or fermentation — that the drying stage has to complete rather than interrupt. Indirect biomass hot air holds these crops within the 40–100 °C range with no combustion product reaching the bean or leaf, which is what keeps smoke taint out of a lot.
Why indirect heat is not optional here
Cocoa and coffee dried over an open fire or in a direct-fired dryer pick up smoke phenols, and smoke taint is a rejection at the fine-flavour end of the market rather than a price deduction. It is the single most common reason a lot that was fermented correctly still fails a buyer’s cup or sensory test.
An indirect generator separates combustion gas from process air through a heat exchanger. The fuel can be crop residue, briquettes or shell, and none of it reaches the bean. For a processor selling into a differentiated market, that separation is the difference between a fuel choice and a quality risk.
Drying completes fermentation — it does not just remove water
For cocoa in particular, the early drying phase carries fermentation reactions to completion. Drying too fast arrests them and locks in acidity; drying too slowly invites mould over a long, humid cycle. A controlled chamber lets the profile be slow where it needs to be slow and then finish reliably, batch after batch, with the temperature and time recorded per lot.
Crops in this family
| Crop | Drying temperature | Target moisture | Process note |
|---|---|---|---|
| Cocoa | 40–60 °C | Product specific | Early phase completes fermentation; smoke taint is a rejection |
| Coffee (parchment) | 40–100 °C chamber range | Product specific | Slow, even moisture reduction protects cup quality |
| Tea (withering) | 40–100 °C chamber range | Product specific | Withering is a controlled moisture loss, not a dry-down |
| Tea (firing) | 40–100 °C chamber range | Product specific | Arrests oxidation at the chosen point |
The equipment behind these crops
- biomass hot air generator
- industrial tunnel dryers
- multi-fuel biomass burner
- turnkey biomass drying plant
Detailed pages by crop and country
Frequently asked questions
Will a biomass dryer put smoke into my cocoa?
Not with indirect heat exchange. Combustion gas passes one side of the exchanger and process air the other, and the two never mix, so no smoke phenol reaches the bean. The generator is a double-chamber, three-pass design moving 2,500 to 3,000 m³/h for exactly this reason, and it is why we do not offer direct-fired drying for this crop family even though it would be cheaper to build.
What temperature should cocoa dry at?
At the low end of our chamber range — 40–60 °C is the working band — and staged rather than flat. The early phase is slow on purpose, because it is completing fermentation. Driving temperature up to shorten the cycle locks in acidity and is the most common way a well-fermented lot is spoiled at the last step.
Can I document the drying profile for a buyer?
Yes. The Delta PLC logs setpoint and actual temperature through the batch, across cycles that run anywhere from 16 to 30 hours depending on the crop, and alarms on deviation. That gives you a per-lot record to attach to a shipment. For buyers in differentiated or certified markets, the record is increasingly part of the sale rather than an extra.
Size a line for your crop
Tell us the product, the daily fresh throughput and the fuel you can source. An engineer replies within one business day.
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