Cashew Processing Steps: From Raw Nut to Export-Ready Kernel

The cashew processing steps that turn a raw cashew nut (RCN) into a clean, export-grade kernel run to sixteen distinct stages across five phases: raw material preparation, conditioning, shelling and separation, kernel processing, and finishing. Each stage feeds the next, and a mistake early in the line cannot be corrected later — it simply shows up as broken kernels and lost value at the packing table.

The interactive walk-through below lets you move through the complete cashew processing process one stage at a time. Every step shows the machine involved, what it does, the key parameters that matter, and why it affects your final yield. It is built by TTQ Co. Ltd., a cashew processing machinery manufacturer and exporter based in Ho Chi Minh City, Vietnam — the country that leads the world in mechanised cashew processing.

Click any stage in the walk-through, or open the full process map to see all sixteen stages at once.

The Five Phases of Cashew Processing at a Glance

Raw cashew nuts arrive at the factory at roughly 8–10% moisture, the level at which they can be safely stored for months between harvest seasons. Before anything else happens, the nuts are cleaned of stones and foreign matter, then calibrated into size grades (A+, A, B, C, D). This calibration step is more important than it looks: the size split is fixed here, before steaming, and it determines which shelling blade setting each batch will meet. It does not change at any later stage.

The calibrated nuts are then steam-conditioned at approximately 100°C for 20–30 minutes, which softens the shell and conditions the cashew nut shell liquid (CNSL) layer so the shell can be cut cleanly without damaging the kernel. After steaming, the nuts are cooled — typically for 12 to 24 hours — until the shell firms up again. Cutting a nut whose shell is still soft crushes the kernel instead of releasing it.

Shelling separates kernel from shell. The kernels move on to drying, where hot air brings kernel moisture down to about 3–4% so the testa (skin) loosens; the shells become a by-product stream, sold for CNSL extraction or burned as boiler fuel. Dried kernels are humidified so they flex rather than snap during peeling, then peeled, colour-sorted, and finally graded into whole white grades — WW180 through WW450, counted per pound under the international AFI/CEPCI standard your buyers quote against.

Across a full line, a realistic planning figure for kernel recovery (KOR) is around 25% as a conservative floor — meaning one tonne of raw cashew nut yields roughly 250 kg of kernel. Well-run plants processing good raw material commonly achieve more. Recovery is the single largest swing factor in the economics of a cashew plant, which is why every stage below is ultimately about protecting it.

Cashew Processing Steps, Stage by Stage

Each step below corresponds to a stage in the interactive walk-through, and links to the machine that performs it.

1. RCN reception and quality check. Incoming lots are weighed, sampled, and cut-tested for moisture, nut count per kg, and expected recovery.
2. Cleaning and de-stoning. Vibratory screening and air aspiration remove stones, sand, and foreign matter that would otherwise damage every machine downstream.
3. Calibration (size grading). An automatic raw cashew nut grading machine sorts the nuts into size grades so each batch can be matched to the correct shelling blade.
4. Steaming. A cashew steaming machine applies saturated steam to soften the shell and condition the CNSL layer.
5. Cooling. Steamed nuts rest until the shell becomes brittle enough to cut cleanly.
6. Shelling. A cashew nut shelling machine — or an automatic cashew cutting machine with blades matched to each size grade — opens the shell without cutting the kernel.
7. Shell and kernel separation. Kernels are separated from cut shells; unshelled and half-cut nuts are recycled automatically back through the sheller.
8. CNSL shell by-product. Cut shells are not waste. They feed cashew nut shell liquid (CNSL) extraction, or fuel the plant's own shell burner and boiler.
9. Drying (Borma treatment). A cashew dryer machine brings kernel moisture down so the testa loosens for peeling.
10. Humidification. A cashew kernel humidification chamber restores controlled moisture so kernels flex instead of breaking in the peeler.
11. Peeling. An automatic cashew peeling machine removes the testa using air and gentle mechanical action.
12. Colour sorting. A cashew nut colour sorter removes scorched, discoloured, and testa-marked kernels. It can be deployed at up to three points in the line — after shelling, after peeling, and at final grading — with each position catching a different defect.
13. Kernel grading. A cashew grading machine sorts kernels into wholes, splits, and brokens by international cashew grade.
14. Final QC and metal detection. A cashew moisture meter confirms packing moisture and a cashew metal detector provides the final food-safety gate before sealing.
15. Vacuum packing. A cashew vacuum packing line seals kernels with nitrogen or CO₂ flush to protect flavour and shelf life through export transit.
16. Cartoning and dispatch. Sealed packs are cartoned, labelled, palletised, and containerised with full lot traceability.

Why the Sequence Matters for Your Yield

It is tempting to look at a cashew line as a list of machines to buy. In practice it is a chain of dependencies, and three links carry most of the weight.

Calibration decides what shelling can achieve. A shelling blade is cut for a specific nut size. Feed mixed sizes into one blade setting and the small nuts get crushed while the large ones are cut too shallow to release cleanly. This is why whole-kernel percentage — the number that sets your selling price — is largely won or lost at the calibrator, several stages before the sheller ever touches a nut.

Humidification decides what peeling costs you. A kernel dried to 3–4% moisture is brittle. Send it straight to a peeler and it snaps, converting whole kernels into splits and brokens worth substantially less per kilo. Controlled re-humidification lets the kernel flex under the peeler instead of breaking. It is the stage buyers most often underestimate — until they see their breakage figures.

Colour sorting is a sequence, not a single machine. A sorter placed after shelling catches shell fragments and CNSL-stained kernels. One after peeling catches testa remnants. One at grading catches scorched and off-colour kernels. Each position removes a defect the others cannot see, which is why three well-placed sorters outperform one oversized machine in the wrong place.

Understanding these dependencies is what separates a plant that hits its recovery target from one that quietly loses several percent of its kernel value every shift. If you are planning a new facility, our fully automatic turnkey cashew processing plant pages set out how these stages are integrated into a single line, and our cashew nut processing project report covers the capital and operating assumptions behind them.

Prefer a static diagram to an interactive tool? See our cashew processing flow chart. For a full breakdown of individual machines, visit our cashew processing machinery range.

Frequently Asked Questions

What are the steps in cashew processing?

Cashew processing runs to sixteen stages across five phases: RCN reception and quality check, cleaning and de-stoning, and calibration; steaming and cooling; shelling and shell–kernel separation, with CNSL shells taken off as a by-product; drying, humidification, peeling, and colour sorting; and finally kernel grading, QC and metal detection, vacuum packing, and cartoning for dispatch.

What machines are needed for a cashew processing plant?

A complete line needs a pre-cleaner and de-stoner, a raw cashew nut grading (calibration) machine, a steam cooker with boiler, shelling machines, a shell–kernel separator, a Borma dryer, a humidification chamber, a peeling machine, one or more colour sorters, a kernel grading machine, a metal detector and moisture meter, and a vacuum packing line. Colour sorters are typically bought-in units from specialist suppliers and are quoted separately from the core line.

What is KOR, and what recovery rate should I plan for?

KOR (kernel outturn ratio) is the weight of kernel obtained from a given weight of raw cashew nut, expressed as a percentage. As a conservative planning floor, use 25% — one tonne of RCN yielding roughly 250 kg of kernel. Actual recovery depends heavily on the origin and quality of the raw nut, and well-run plants processing good material commonly do better. Because recovery is the largest single swing factor in a plant's financial model, we recommend planning against the conservative figure rather than the best case.

Why are cashew nuts steamed before shelling?

Steaming at around 100°C softens the hard outer shell and conditions the CNSL layer inside it, so that the shell can be cut open without the blade crushing the kernel or contaminating it with shell liquid. After steaming, the nuts must be cooled — typically overnight — so the shell firms up again before cutting.

What is the difference between shelling and peeling?

Shelling removes the hard outer shell from the raw cashew nut to release the kernel. Peeling removes the thin brown skin, called the testa, from the kernel itself, several stages later and after the kernel has been dried and humidified. They are different machines doing different jobs at different points in the line.

What are cashew kernel grades such as WW320?

Whole white (WW) grades are defined by kernel count per pound under the AFI/CEPCI international standard. WW320 means approximately 320 kernels per pound — the lower the number, the larger the kernel and the higher the price. Common grades run from WW180 (largest) through WW210, WW240, WW320, and WW450. Kernels that break during processing are classified and sold as splits, butts, or brokens at lower prices.

What happens to the cashew shells after processing?

Cashew shells are a revenue and energy stream, not waste. They are sold for cashew nut shell liquid (CNSL) extraction — an industrial raw material used in resins, brake linings, and coatings — and the residual shell cake is burned as boiler fuel, which in a well-designed plant can supply most or all of the steam the process itself requires.

Talk to Us About Your Cashew Processing Line

TTQ Co. Ltd. manufactures and exports complete cashew processing lines from Ho Chi Minh City, Vietnam, and has supplied plants across West Africa, Southeast Asia, and beyond. Whether you are planning a first facility or expanding an existing one, we can advise on the machine configuration and capacity that fits your raw material and your market.

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