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Yam flour processing
Yam washing, peeling, slicing, blanching, drying and flour milling — white yam flour, elubo, dried yam chips
The commercial reality
Yam flour is a drying business. Roughly 4 tonnes of fresh yam make one tonne of flour, and the dryer removes about 2 tonnes of water along the way. That means the dryer, not the mill, sets your capacity, your energy bill and your colour. Everything before it exists to hand the dryer thin, uniform, blanched chips that dry fast and stay white.
Process flow diagram
Generated for the standard configuration. Yours is redrawn to your product mix, capacity and site.
Process chart
Every stage with the equipment that performs it, the operating parameter and the control point that decides quality.
| # | Stage | Equipment | Parameter | Control point |
|---|---|---|---|---|
| 01 | Reception and sorting | Inspection and sorting conveyor | Weigh, remove rotten and sprouted tubers | Rot and mould kept out of the line |
| 02 | Washing | Fruit and vegetable washer | Brush or drum washer, recirculated filtered water | Soil and grit removed before peeling |
| 03 | Peeling | Root and tuber peeler | Abrasive roller peeler, then hand trim | Peel removed with minimum flesh loss |
| 04 | Slicing | Slicer, dicer and shredder | Chips 3–5 mm | Uniform thickness sets drying time |
| 05 | Blanching | Blancher, hot water or steam | 75–90 °C, 2–5 min, optional citric acid dip | Enzyme browning stopped, colour held |
| 06 | Drying | Multi-pass belt dryer | 55–70 °C hot air, staged temperature zones | 65–70% → 10% moisture or below |
| 07 | Cooling | Cooling conveyor | Ambient air, chips cooled before milling | No condensation, no sweating in storage |
| 08 | Milling | Hammer or pin mill | Hammer mill, 0.5–1 mm screen | Particle size and mill temperature |
| 09 | Sieving | Vibro sifter | 250 µm (60 mesh), oversize recycled | Smooth, lump-free flour |
| 10 | Packing | Filling, sealing and packing line | 1, 5 and 25 kg bags, metal detection | Fill weight, seal integrity, moisture barrier |
Mass balance
Basis of 1,000 kg of raw material. Change the tonnage below and the whole table rescales.
| Stage | Output, kg/h | Yield | Loss, kg/h | Where the loss goes |
|---|---|---|---|---|
| Fresh yam received | 1,000 | 100% | 0 | — |
| After sorting and washing | 970 | 97% | 30 | Rotten tubers, soil and grit |
| After peeling and trimming | 800 | 80% | 170 | Peel and trim to drying for animal feed |
| Blanched chips | 780 | 78% | 20 | Slicing fines and solids leached in blanch water |
| Dried chips at 10% moisture | 260 | 26% | 520 | Water evaporated in the belt dryer |
| Yam flour, sieved | 250 | 25% | 10 | Milling dust, collected and returned |
By-products: Peel and trim dried on the same belt dryer for animal feed; whole dried chips sold as a product in their own right; blanch water settled to recover starch.
Equipment schedule
Core machines for this line. Conveying, tanks, dust collection and utilities are added to suit the layout.
| Equipment | Category | Function |
|---|---|---|
| Inspection and sorting conveyor | Preparation | Removes rotten, sprouted and damaged tubers before they reach the washer. |
| Fruit and vegetable washer | Preparation | Removes field soil and grit with recirculated, filtered water. |
| Root and tuber peeler | Preparation | Abrasive rollers strip the skin; peel loss is the biggest yield lever on the line. |
| Slicer, dicer and shredder | Preparation | Uniform chips — cut thickness sets drying time and dryer size. |
| Blancher, hot water or steam | Thermal | Stops enzymatic browning so the flour stays white; longer cycle for elubo. |
| Multi-pass belt dryer | Drying | Continuous hot-air drying in staged zones; the heart of the line. |
| Cooling conveyor | Drying | Brings dried chips to ambient so they mill cleanly and store without sweating. |
| Hammer or pin mill | Separation | Grinds dried chips to flour with dust collection. |
| Vibro sifter | Separation | Grades flour to size and returns oversize to the mill. |
| Filling, sealing and packing line | Packing | Weighing, filling, sealing, metal detection and case packing. |
Questions we get on this line
White yam flour or elubo?
White yam flour is blanched briefly and dried fast to keep a cream colour; it sells to bakeries, snack makers and export retail. Elubo is parboiled and steeped longer, which gives the brown colour and flavour West African consumers expect for amala. The same line makes both: only the blanching time and temperature change.
Why a belt dryer and not sun drying?
Sun drying takes days, depends on weather and exposes chips to dust, insects and mould. A belt dryer finishes in hours at a controlled temperature, so colour, moisture and microbial load are the same batch after batch, which is what export buyers and supermarkets audit for.
How much heat does the dryer need?
Roughly 2 kg of water leaves the dryer for every kg of flour made. A well-designed belt dryer needs about 3,500 to 4,500 kJ per kg of water evaporated, so on a 2 t/h fresh yam line that is in the order of 1 MW of heat. Fixing the heat source, whether biomass, gas, diesel or steam, is the first decision in the feasibility.
Want this line costed for your tonnage?
Send your yam variety, dry matter and the capacity you are targeting. You get a flow diagram, an equipment schedule and a budget number.