Cashew Processing Steps (Step by Step)
Walk the line, one step at a time
A step-by-step walk through cashew processing — what happens at each of the eight core stages, why it matters, and which machine does the work.
The cashew processing line runs in eight steps. (1) Raw nuts are calibrated by size. (2) They are steamed at 3–4 bar for 20–25 minutes to soften the shell. (3) An automatic cutter shells them to release the kernel. (4) Kernels are borma-dried over 13–14 hours to 3–4% moisture, which makes the testa brittle. (5) They are humidified back to about 5–6% at the surface so the testa releases without breaking the kernel. (6) They are dry-peeled to remove the testa. (7) Kernels are graded by size (W180–W450) and colour-sorted. (8) They are vacuum-packed with metal detection for long shelf life. Each step maps to a dedicated TTQ machine.
Cashew processing runs to eight core stages, from raw nut reception to a packed export kernel. Every stage exists because the one after it will not work otherwise — which is the single most useful thing to understand before buying any of the machines involved.
The eight core stages
| Stage | What it does | Machine | Moisture at exit |
|---|---|---|---|
| 1. Calibration | Sorts raw nuts into uniform size bands so one machine setting suits a whole batch | Raw-nut size sorter | 8–10% |
| 2. Steaming | 3–4 bar for 20–25 minutes softens the shell so it cuts instead of shattering; nuts then cool and rest 12–24 hours | Steaming machine + boiler | 9–12% |
| 3. Shelling (cutting) | Blades split the shell and release the kernel, ideally whole | Shelling / cutting line | 9–12% |
| 4. Borma drying | 13–14 hours per batch until the testa turns brittle enough to separate | Borma dryer | 3–4% |
| 5. Humidification | Surface moisture raised back so the testa releases without breaking the kernel | Humidifier room | 5–6% at the surface |
| 6. Peeling | Air and friction remove the testa; 80–90% peel on the first pass | Peeling machine + air compressor | 5–6% |
| 7. Grading and colour sorting | Sized into W-grades, then optical removal of scorch, specks and foreign material | Classify machine + colour sorter | — |
| 8. Packing and metal detection | Vacuum sealed and checked for ferrous, non-ferrous and stainless contamination | Vacuum line + conveyor metal detector | 3–5% |
Raw nuts arrive at roughly 8–10% moisture and leave as kernels at 3–5%. Moisture is the thread running through the whole line — every stage either removes it or puts a controlled amount back. TTQ’s equipment catalogue lists sixteen machine stages; that is catalogue structure, not the process. The process is these eight.
Why the sequence decides your yield
It is tempting to read a cashew line as a shopping list of machines. In practice each stage sets the ceiling for the next, so buying an excellent machine for one stage and a poor one for the stage before it wastes the money spent on both.
Grading determines cutting
blades are set for a size band. Feed mixed sizes and you either crush the small nuts or fail to open the large ones.
Steaming determines breakage
an under-steamed shell shatters and takes kernel with it; an over-steamed kernel is soft and marks. 3–4 bar for 20–25 minutes is the window, and no cutting machine compensates for missing it in either direction.
Borma drying and humidification determine peeling
the testa only releases cleanly when surface moisture is raised while the core stays dry — that is two separate machines in two separate rooms, the borma dryer and the humidifier. Miss the 2–4 hour window after humidification and the gradient equalises.
Peeling determines grade value
white whole kernels earn the premium. Breakage here converts premium product into brokens permanently.
Colour sorting removes defects, it does not create quality
it is the last check, not a repair stage.
KOR — two different numbers, and why they must not be compared
KOR means "kernel outturn ratio", and the trade uses the term for two measurements that are not interchangeable. Quality-check KOR is what you use when buying raw nuts: outturn measured on a sample and expressed in pounds of recoverable kernel per 80 kg bag, typically 42–52 lbs. It prices the RCN. Production KOR is what you use when running a factory: kilograms of final, packed, saleable kernel per 100 kg of RCN actually processed, after shelling, peeling, grading losses and rejects — typically 22–24 kg per 100 kg.
These are two different measures — do not compare one to the other. A sample outturn of 48 lbs per 80 kg bag is about 27% laboratory outturn; a production KOR of 22–24% is the realistic factory yield, and it is lower because it counts only what you can actually sell. Plan working capital against the production number, not the buying number: 1,000 kg of RCN is about 220–240 kg of saleable kernel, and only part of that is whole white.
What happens to the shell
Shell is roughly 70% of raw nut weight and it is a revenue and energy stream rather than waste. It can be burned in a shell burner as boiler fuel — displacing purchased coal or diesel — or pressed for CNSL first and the de-oiled cake burned afterwards. Either route turns a disposal cost into a saving, and the fuel loop is the cleanest economics on the whole site.
Capacities across this site are quoted per 8-hour shift. A shelling line can run three shifts; a complete plant cannot, because drying and humidification are batch stages needing turnaround. For the stage-by-stage machine detail see the processing flow chart, and for the machines themselves the machinery hub.
- Calibration — raw nuts sized for even shelling. Grading machine →
- Steaming — 3–4 bar for 20–25 min softens shells. Steaming machine →
- Shelling — automatic cutters release the kernel. Shelling machine →
- Borma drying — 13–14 h per batch to 3–4% moisture. Dryer →
- Humidification — surface back to 5–6% before peeling. Humidifier →
- Peeling — dry removal of the testa skin. Peeling machine →
- Grading & colour sorting — W-grades and optical defect removal. Grading machine →
- Packing & metal detection — vacuum packing, checked before dispatch. Packing machine →
Between steps, shell waste is routed to the shell burner for energy, and every stage is tuned to protect whole-kernel yield.
The process, drawn
The eight core stages
Raw cashew nut in at one end, packed export kernel out at the other. Moisture is the thread: every stage either takes it out or puts a controlled amount back.
Capacities and cycles are Size A basis, per 8-hour shift. Stages 04 and 05 are separate machines in separate rooms — the borma oven dries, the humidifier puts moisture back.
KOR means two different things
Both are called "kernel outturn ratio". They are not interchangeable, and comparing one to the other is the most common costing error in the trade.
- Measured on a sample Cut, separated, weighed
- Pounds per 80 kg bag 42–52 lbs
- Laboratory outturn 48 lbs ≈ 27%
- Prices the consignment What the broker quotes
- Measured across the plant After every loss and reject
- kg per 100 kg of RCN 22–24 kg
- Realistic factory yield Counts only saleable output
- Sizes working capital What you plan against
These are two different measures — do not compare one to the other. Production KOR is lower because it counts only what you can actually sell, after shelling, peeling and grading losses.
Frequently asked questions
What are the steps in cashew nut processing?
How long does steaming take?
Related reading & machines
Cashew Processing Flow Chart
A flow chart of cashew processing showing the input, output and machine at each stage — from raw cashew nut in to sealed kernel out.
Open →
Cashew Nut Processing: The Complete Process
Raw nut to premium kernel, stage by stage
Open →
Fully Automatic Cashew Processing Plant
From raw nut to sealed kernel — one automated line
Open →Talk to a cashew engineer
Tell us your target capacity, grades and location — we’ll come back with a costed proposal.