Biomass hot air systems for spice drying and roasting

Roasting versus drying — why the heat profile differs

A drying cycle holds a moderate temperature for hours, and the limit is how fast moisture can migrate out of the product. A roasting cycle applies a much higher temperature for minutes or seconds, and the limit is how quickly the surface develops without scorching. They are different processes that happen to share a fuel and, up to a point, a machine.

The practical consequence is residence time. A tunnel chamber holds product in warm air for 16 to 30 hours; a roaster moves product through a hot zone quickly and then arrests the reaction with a cooling stage. Puffing goes further again — moisture inside the grain has to flash to steam faster than it can escape, which is a thermal shock rather than a temperature.

Where this platform stops

Two things on this page need saying before an enquiry, because they are the difference between a system that works and an argument at commissioning.

Grain puffing is not a duty this platform performs. Puffing rice into murmura is a high-temperature, short-time treatment — roughly 150 to 250 °C for 9 to 45 seconds, conventionally in hot sand as the heat-transfer medium — and the generator’s delivered air tops out at 150 °C. The heat grade is wrong and so is the transfer method. If you are building a puffing line, we are not the supplier for that stage, and we would rather say so here than at the quotation.

Spice roasting divides in the same way. Cumin optimises around 125 °C, and light aroma roasting of whole seed at 120–150 °C is comfortably inside the range. Darker roasting — coriander is the common case, around 163 °C, and general practice runs to 177 °C — is above it. We can supply the drying and light-roasting stages of a spice line; the dark-roast stage needs equipment built for it.

Applications

• Spice drying and aroma roasting — cumin, coriander, fenugreek
• Spice roasting ahead of grinding — cumin, coriander, fenugreek
• Groundnut and pulse roasting
• Grain and cereal roasting for flour and snack production
• Pre-roast drying, which is a conventional hot air duty rather than a roasting one

Aroma carry-over and product changeover

Roasting concentrates aroma deliberately, which means it concentrates the carry-over problem too. A roaster that has run cumin will flavour whatever follows it, and the residue sits in ducting and on surfaces as much as in the chamber. Plan the running order from mildest to strongest, with a documented cleaning protocol at the end of it.

Where a line must run both food and non-food products, or an allergen alongside a non-allergen, that is a zoning decision taken at design stage rather than a cleaning decision taken afterwards.

Specifications

For the underlying equipment see the biomass hot air generator; for the fuel stage see the biomass pellet burner. Spice drying, as distinct from spice roasting, is covered on the spices and botanicals hub. The nearest sibling duty is papad drying.

Supply outside West Africa

We accept orders from any country. West Africa is the market these systems are engineered around and where most of them go, but there is no territory we will not supply.

Lead time, warranty and scope of supply do not change with the destination: manufacture in 10–18 weeks from confirmed order and receipt of advance payment, warranty 12 months from date of shipment, and spares dispatched alongside the machines. For installation outside the region the buyer covers the team’s travel, accommodation and entry formalities — stated up front because it is a real line in the budget. Documentation and the operator interface are supplied in English and French; other languages on request.

Frequently asked questions