Introduction

A cashew kernel looks simple: pale, curved, smooth and ready to eat. But no nut takes more work to reach the shop. Each kernel has to be freed from a hard double shell filled with a caustic liquid, separated from a thin papery skin, sorted by size and colour, and packed so it stays crisp and fresh. Much of this work still depends on skilled hands, which is one reason cashews are one of the more valuable nuts in the world.

We grow cashews on our own plantation, and our harvest supplies the Udari Nuts & Spices range: Udari Cashew Nuts, our whole natural kernels, and Udari Oven Roasted Cashews, which we roast in dry heat and never fry. Our cashew plantation guide explains how we grow and harvest the nuts. This article follows what happens next.

It explains each stage of cashew processing, from raw nut to finished kernel: drying and storage, conditioning, shelling, kernel drying, peeling, grading, quality checks and packing. It explains what cashew grades such as W240 and W320 mean, how roasted cashews are made, and what happens to the shells and skins. It ends with how to choose and store cashews, and answers common questions.

Why cashew processing is different

Most nuts can be cracked and eaten. The cashew cannot. Its shell has two layers, and between them is a honeycomb filled with cashew nut shell liquid (CNSL). This dark, oily liquid contains anacardic acid, cardol and related compounds. It can burn skin, irritate the mouth and contaminate the kernel if the shell is broken carelessly.

Cashew processing is therefore built around one challenge: opening the shell and taking out the kernel whole, without letting the shell liquid touch it, and without breaking the brittle kernel. Every stage is designed to make the shell easier to open, protect the kernel and preserve its colour and flavour.

Stage 1: Drying and storing raw nuts

Processing begins on the plantation. After harvest, raw cashew nuts are sun-dried until their moisture falls to a safe level for storage, usually below about 8% to 10%. Well-dried nuts rattle in their shells. They are then packed in breathable jute sacks and stored in dry, ventilated stores, off the floor.

Correct drying and storage matter because raw nuts that stay damp can develop mould, which can spoil the kernel and, in the worst cases, produce harmful toxins. Dry, well-stored raw nuts keep for months, so processing can continue after the harvest season ends.

Stage 2: Cleaning and calibration

Before processing, raw nuts are cleaned to remove dust, stones, bits of cashew apple and other foreign matter. They are then calibrated, which means sorted by size, usually with rotating screens. Calibration matters because nuts of similar size can be conditioned and shelled more evenly, which means fewer broken kernels.

Stage 3: Conditioning (steaming or roasting the shell)

The shell has to be made brittle, and the shell liquid has to be dealt with, before the nut is opened. This is called conditioning. There are two main methods:

• Steam conditioning. Nuts are steamed in a pressure vessel for a set time. The heat makes the shell brittle and slightly separates the kernel from the shell, while the liquid stays mostly within the shell. Steaming is widely used today because it gives cleaner kernels with good colour.
• Roasting the shell. In traditional methods, nuts were roasted in open pans or drums, or in a bath of hot shell liquid, which burned off or extracted much of the liquid. These methods are older and produce smoke and fumes, so many processors have moved to steaming.

After conditioning, the nuts are cooled and rested, often for a day, so the shells are ready for cutting.

Stage 4: Shelling (cutting)

Shelling opens the shell and frees the kernel. It can be done in several ways:

• Manual or hand-and-leg operated cutters. The worker places each nut between curved blades shaped to the nut and presses a lever to split the shell. The kernel is then lifted out with a pin. This method is slow, but skilled workers produce a high proportion of whole kernels.
• Semi-automatic cutters. Machines split the nuts, and workers separate kernels from shells by hand.
• Automatic shelling lines. Machines cut and separate shells and kernels at high speed, with sorting to remove pieces of shell.

Workers who handle freshly shelled nuts wear gloves or protective oil to avoid contact with shell liquid. The aim at this stage is to keep kernels whole and clean, because whole kernels are worth far more than broken ones.

Stage 5: Drying the kernels

Freshly shelled kernels are still covered with a thin reddish-brown skin called the testa, and they contain too much moisture to keep well. The kernels are dried in heated drying chambers, traditionally called bormas, for several hours at controlled temperatures. Drying lowers the kernel’s moisture to a few per cent, which protects it from mould and loosens the testa so it can be removed.

Temperature control is critical. If the kernels are dried too hot or too long, they scorch and darken. If they are not dried enough, the testa sticks and the kernels spoil more quickly. After drying, kernels may be rested in a humid room for a short time, so they become slightly less brittle before peeling.

Stage 6: Peeling

Peeling removes the testa. Much of this is still done by hand, with workers rubbing or scraping the skin off each kernel with a small knife or bamboo blade. Air-blast and mechanical peelers are also used, with hand finishing for kernels that keep some skin.

Peeling has to be gentle, because the dried kernel is brittle. Kernels that break during peeling are graded as splits or pieces, and kernels with traces of skin left on them are cleaned again or graded separately.

Stage 7: Grading

Every kernel is graded by size, colour and wholeness. Cashew grades follow internationally recognised standards. The most common grade names use letters for the type and numbers for the size.

What the letters mean

What the numbers mean

For whole kernels, the number shows roughly how many kernels make up one pound (about 454 g). The smaller the number, the larger the kernels.

Splits, butts and pieces are just as good to eat as whole kernels. They are ideal for cooking, baking, sweets and cashew paste, and they usually cost less.

Stage 8: Quality checks

Throughout processing, and before packing, kernels are checked for:

• Moisture, to make sure they will stay crisp and free of mould;
• Colour, so each grade is consistent;
• Defects, such as insect damage, spots, rancidity or traces of testa or shell;
• Foreign matter, including pieces of shell, stones and other contaminants; and
• Food safety, including hygiene during handling and, where required, laboratory checks.

Every lot that goes into Udari products is checked against these points before it is packed.

Stage 9: Packing

Dried cashew kernels pick up moisture and odours easily, and their natural oils can go rancid if exposed to air, heat and light. Packing protects them. Commercial cashew kernels are usually packed in vacuum-sealed or gas-flushed pouches or tins, which remove oxygen and keep the kernels fresh for months.

Udari Cashew Nuts are sealed airtight to keep the kernels crisp and fresh.

How Udari Oven Roasted Cashews are made

Udari Oven Roasted Cashews start as whole kernels and are then roasted in dry heat in an oven, never fried in oil. Dry roasting brings out a deeper, toasty flavour and a satisfying crunch.

Roasting needs care. Cashews roasted too long or too hot turn dark and bitter; roasted too little, they stay soft and pale. Kernels are spread evenly, roasted at a controlled temperature, cooled quickly and packed as soon as they are cool, before they can absorb moisture. Because we never fry them, Udari Oven Roasted Cashews contain no added frying oil.

How much kernel does a raw nut give?

Cashew buyers and processors measure the value of raw nuts by how much good kernel they contain. Two simple measures are used around the world:

• Nut count. The number of raw nuts in one kilogram. Fewer nuts per kilogram means larger nuts, which usually give larger kernels.
• Kernel outturn. The weight of good kernel obtained from a standard quantity of raw nuts. In international trade this is often expressed in pounds of kernel per 80 kg bag of raw nuts.

As a rough guide, only around 20% to 25% of the weight of a raw cashew nut ends up as kernel. The rest is shell, shell liquid and testa. Kernel outturn depends on the variety, the growing season, how fully the nuts matured on the tree, how well they were dried and stored, and the skill of the processing.

This is one reason we collect only nuts that have fallen naturally and are fully mature. Immature nuts may look normal on the outside but contain shrivelled kernels, which lower the outturn of the whole batch. Our bulk supply guide explains how raw nuts are sampled and tested.

Freshness: keeping cashews crisp and sweet

Cashew kernels are rich in natural oils, mostly unsaturated fats. These oils give cashews their creamy texture and buttery flavour, but they also make kernels sensitive to their surroundings. Three things shorten a cashew’s life:

• Moisture. Kernels that absorb moisture lose their crunch, become soft and can develop mould.
• Oxygen. Over time, oxygen reacts with the oils, causing rancidity: a stale, bitter or paint-like taste and smell.
• Heat and light. Warmth and sunlight speed up rancidity.

That is why careful drying, cool storage, airtight packaging and quick packing after roasting all matter. A cashew kept airtight, cool and dark stays fresh far longer than one left in an open bowl on a sunny shelf.

The skills behind every cashew

Even with modern machines, cashew processing relies on skilled people. Experienced workers judge when nuts are properly conditioned, operate cutters so kernels come out whole, peel kernels without breaking them and sort grades by eye with remarkable accuracy. Careful handling at every step is what separates a pack of pale, whole kernels from a pack of broken, scorched ones.

What happens to the rest of the cashew?

Only about a fifth to a quarter of a raw cashew nut’s weight becomes kernel. Much of the rest has uses:

• Cashew nut shell liquid is used in industry to make resins, paints, coatings and brake linings.
• Shells left after extraction can be used as fuel.
• Testa contains tannins and can be used in some industrial and animal feed applications.
• Cashew apples left on the plantation return organic matter to the soil, and in some places are made into juice, jam or drinks.

Making use of these by-products reduces waste and makes cashew production more sustainable.

Choosing and storing cashews at home

When you buy cashews, look for:

• Even, pale colour, unless you are buying roasted cashews;
• Whole, unbroken kernels, if you want them for snacking or presentation;
• A fresh, sweet smell, with no sign of rancidity; and
• An airtight pack with a clear best-before date.

At home, keep cashews in an airtight container in a cool, dark place. Once a pack is opened, close it tightly or move the nuts to a sealed jar. In hot, humid weather, store opened cashews in the refrigerator. For longer storage, cashews can be frozen in an airtight container.

Udari Cashew Nuts and Udari Oven Roasted Cashews

Our harvest becomes two Udari products:

• Udari Cashew Nuts: whole natural kernels, selected for size, pale colour and a sweet, buttery taste. They are not roasted, salted or flavoured, so they suit every kind of cooking: soak and simmer them into a creamy kaju curry, fry them in ghee to top biriyani and yellow rice, chop them into love cake and dodol, or blend them into a smooth paste that enriches curries without cream.
• Udari Oven Roasted Cashews: whole cashews roasted in dry heat until golden and crunchy, never fried in oil. They are made for snacking, gifting and sharing.

Both contain cashew nuts, which are tree nuts and a common allergen. You can find them on our Udari Nuts & Spices page, and our Udari Cashew Nuts article has more ideas for cooking with them. Our article on cashew nut benefits explains what cashews offer nutritionally.

Illustrative example

The following example is illustrative and does not describe a specific batch or figures.

At the end of the harvest season, dried raw nuts from our plantation are taken out of storage. A sample is checked for moisture, nut count and kernel yield before the batch is cleaned and calibrated into three sizes.

Each size is steamed separately, cooled and rested overnight. The next day, the nuts are shelled. Whole kernels are separated from splits and pieces, then dried in heated chambers at a controlled temperature. After peeling, the kernels are graded by size and colour. Large, pale whole kernels go forward for Udari Cashew Nuts. Another lot is dry-roasted, cooled and packed as Udari Oven Roasted Cashews. Before packing, every lot is checked again for moisture, colour and defects.

Frequently asked questions

Are “raw” cashews really raw?

Not completely. All cashews sold for eating have been heated during conditioning and kernel drying, because the shell liquid makes truly raw cashews unsafe. “Raw” in shops usually means the kernels have not been roasted or flavoured after processing.

What is the best cashew grade?

It depends on your use. W180 and W210 are the largest and most prestigious wholes; W240 and W320 are excellent for snacking; splits and pieces are ideal for cooking.

Why are cashews more expensive than many other nuts?

Because processing is slow and labour-intensive, and only about a fifth to a quarter of the raw nut’s weight becomes kernel.

Are Udari Oven Roasted Cashews fried?

No. They are roasted in dry heat in an oven and never fried in oil.

How long do cashews keep?

Unopened, airtight packs keep for months. Once opened, keep cashews airtight in a cool, dark place, or in the refrigerator in hot weather.

Are Udari cashews from your own plantation?

Yes. Our cashew plantation supplies the Udari Nuts & Spices range.

Conclusion

Turning a raw cashew nut into a clean, whole kernel takes skill and patience: drying, conditioning, shelling, kernel drying, peeling, grading, checking and packing, with each step protecting the kernel’s colour, flavour and shape.

By growing our own cashews and following them through every stage, we can make sure Udari Cashew Nuts and Udari Oven Roasted Cashews meet the standard our customers expect, from plantation to pack.

Ready to taste the difference? Explore Udari cashews.

Shop Udari Cashews

Sources

• FAO, cashew cultivation and processing practices in Sri Lanka: https://www.fao.org/4/ac451e/ac451e08.htm
• Association of Food Industries, cashew kernel grade specifications: https://www.afius.org/
• Sri Lanka Cashew Corporation, annual reports (Parliament of Sri Lanka): https://www.parliament.lk/uploads/documents/paperspresented/annual-report-srilanka-cashew-corporation-2013.pdf
• The Sunday Times (Sri Lanka), cashew industry in a crunch amid rising demand (July 2025): https://www.sundaytimes.lk/250713/business-times/cashew-industry-in-a-crunch-amid-rising-demand-bureaucratic-hurdles-603719.html