Where Do Cashews Come From and How Are They Processed?

Cashews grow on tropical evergreen trees native to northeastern Brazil, and the path from tree to snack bag is one of the most labor-intensive in the nut world. The kidney-shaped kernel sits encased in a double-walled shell filled with a caustic oil that can blister skin on contact, which is why you never see cashews sold in their shells the way you see pistachios or peanuts. Every single cashew has to be carefully extracted, and most of that work still happens by hand in countries across the tropics.

A Brazilian Tree That Went Global

The cashew tree, Anacardium occidentale, is native to northeastern Brazil and was introduced to Asia and Africa by Portuguese explorers during the sixteenth century.¹ The Portuguese saw the tree as a useful tool for coastal erosion control as much as a food source, and they planted it widely along tropical shorelines in India, Mozambique, and elsewhere.² From those initial plantings, cashew cultivation spread across West Africa, East Africa, and Southeast Asia. Today, Vietnam, India, and Côte d’Ivoire are among the world’s largest producers, even though the tree’s ancestral home remains Brazil.

Cashew trees thrive in warm, low-altitude climates with well-drained sandy soils. They tolerate drought better than many tropical fruit trees but are sensitive to frost, which keeps commercial production firmly within the tropics and subtropics. A mature tree can produce fruit for decades, and some smallholder orchards in West Africa and India rely on trees that were planted generations ago. The trees grow to roughly 10 to 12 meters tall, though dwarf varieties bred for easier harvesting are becoming more common.

The Strange Anatomy of a Cashew Fruit

If you have only ever seen cashews as pale, curved kernels in a jar, the actual fruit of the tree looks bizarre. What most people would call the “cashew fruit” is really a swollen, pear-shaped stalk called the cashew apple. It can be red, orange, or yellow and is technically a pseudofruit because it develops from the flower’s receptacle rather than the ovary. The true fruit is the hard, kidney-shaped shell dangling from the bottom of the apple, and inside that shell sits the edible kernel.

The cashew apple is extremely juicy and perishable, with moisture content above 80% and roughly 10% sugars by weight.³ In Brazil and parts of West Africa, the apple is pressed into juice, fermented into alcohol (called “feni” in Goa, India, and “cajuína” in Brazil), or made into preserves. But in most producing countries, especially in Asia, the apple is discarded entirely because the real money is in the nut. The fact that the apple spoils within a day or two of harvest, while the nut in its shell can be stored for months, makes this economic calculation straightforward for most farmers.

What Makes the Shell So Dangerous

The cashew shell has a honeycomb-like structure between its inner and outer walls, and that space is filled with cashew nut shell liquid, or CNSL. The main active compounds in CNSL are anacardic acids, which are derivatives of salicylic acid with a long carbon side chain.⁴ These compounds are chemically related to urushiol, the same substance that gives poison ivy its sting. Direct skin contact with CNSL causes blistering, burns, and allergic dermatitis, which is the fundamental reason cashew processing is so complicated. You cannot simply crack open a cashew the way you would a walnut.

CNSL is not purely a nuisance, though. It has real industrial value and is used in the production of resins, coatings, and friction linings for brake pads. Researchers have developed alkyd-free bio-based coatings using CNSL as a starting material, and these formulations show competitive hardness and stability compared to conventional commercial coatings.⁵ For processing facilities, selling the extracted shell liquid as an industrial byproduct helps offset costs.

From Harvest to Kernel

Cashew processing is a multi-step sequence designed around one central problem: how to get the edible kernel out of the shell without contaminating it with CNSL and without breaking the kernel in the process. Whole, unbroken kernels command a significantly higher price than broken pieces, so every step has to balance throughness of shell removal against gentleness.

Drying and Thermal Pre-Treatment

After harvest, raw cashew nuts (still in their shells) are sun-dried or mechanically dried to reduce moisture content. The dried nuts are then thermally treated to make the shell brittle and easier to crack. The most common industrial method is steam-boiling the dried nuts at about 100 psi for 25 to 30 minutes, then letting them cool naturally for 12 to 24 hours.⁶ This steam-boiling approach preserves the white or ivory color of the kernel and improves the whole-kernel recovery rate. Under optimized conditions, whole-kernel recovery can exceed 90% for large nuts.⁶ An older method, open-pan roasting, heats the shells over fire to release the CNSL but tends to discolor the kernels and is harder to control safely.

Shelling

Once the shells are brittle, the nuts are cracked open. In large mechanized factories, this is done with semi-automatic machines that apply controlled pressure. But in many parts of the world, shelling is still done entirely by hand. Workers use simple tools or their hands to crack each shell and extract the kernel, a process that is slow and physically demanding.⁷ Hand-shelling allows for more careful kernel extraction, which is one reason it persists: broken kernels sell for a fraction of the price of whole ones. But the human cost is high, as workers risk direct contact with residual CNSL, and repetitive motion injuries are widespread.

Peeling and Drying the Kernel

After shelling, the kernel is still covered in a thin reddish-brown skin called the testa. This skin is removed through a secondary drying step followed by manual or mechanical peeling. Research into infrared drying has shown that the temperature and duration of this step directly affect kernel color, brittleness, and how easily the testa peels away. Optimal results for infrared processing occur at around 55°C for 55 minutes, yielding kernels that are easy to peel without excessive browning.⁸ In traditional facilities, workers peel the testa by hand, which requires dexterity and adds another repetitive-motion step to the process.

Grading

The final step before packaging is grading. Cashew kernels are sorted by size, color, and whether they are whole or broken. The highest grade, often labeled “W-180” or “W-210” (the numbers refer to the count of kernels per pound), consists of large, pale, unbroken wholes. Split halves, pieces, and discolored kernels are graded lower and priced accordingly. Grading has traditionally been done by hand, though some facilities are adopting computer vision systems to standardize the process.

The Human Cost of Cashew Processing

Cashew processing is one of the more hazardous food-industry jobs, and the health impacts on workers have been well documented, especially in India, which handles a huge share of global cashew processing. A study of workers in cashew processing units in Kerala found that about 56% reported musculoskeletal disorders, roughly 48% had dermatological problems, and about 19% had chronic lung issues.⁹ Workers in the shelling and peeling sections were significantly more likely to have skin problems, consistent with exposure to residual CNSL.

Research from Tamil Nadu tells a similar story. Low back pain affected about 36% of workers, and wrist or hand pain affected roughly a third. The shelling section was worst for back pain, with nearly 80% of shellers affected, while peeling workers experienced the most wrist and hand injuries. Burns were noted only among roasting and shelling workers, and eye irritation was most common among peelers. Respiratory problems were concentrated among roasting workers, who are exposed to fumes from heated CNSL.¹⁰ Many facilities lacked proper protective equipment, hand-washing stations, and on-site medical services.¹⁰

The transition from purely manual shelling to semi-automatic machines has reduced back pain somewhat, but the overall hazard profile has not changed much because the fundamental exposures remain the same. This reality is part of why fair-trade and ethically sourced cashew certifications exist: the processing workforce, which is predominantly female in many regions, bears real physical consequences for a product that commands premium prices in wealthy consumer markets.

What You Actually Get Nutritionally

Cashew kernels are roughly half fat by weight, with about 80% of that fat being unsaturated. Oleic acid, the same monounsaturated fat found in olive oil, accounts for about 61% of total fat in raw cashews. Protein makes up about 21 grams per 100 grams, and carbohydrates contribute another 20 or so grams.¹¹ The kernels are cholesterol-free. Potassium is the most abundant mineral, and vitamin E is the most abundant vitamin.¹¹

Cashews contain all essential amino acids, with glutamic acid the most prevalent. Roasting changes the amino acid profile: heating at high temperatures for extended periods reduces some amino acids like lysine while increasing others like histidine. For example, roasting at 160°C for 60 minutes reduced lysine by about 18%.¹² For most people eating cashews as a snack, this difference is minor, but it is a reminder that “raw” and “roasted” are not nutritionally identical.

One nutritional footnote worth knowing: cashews can trigger allergic reactions. The allergens are seed storage proteins, including vicilin-like and legumin-like globulins.¹³ Cashew allergy is classified as a tree nut allergy, and for those who are sensitized, reactions can be severe. Cross-reactivity with pistachio is particularly well documented because the two are botanical relatives in the same family.

Why “Raw” Cashews Are Never Actually Raw

If you buy a bag labeled “raw cashews,” you are buying kernels that have been steam-treated and shelled but not roasted or seasoned afterward. Truly raw, unprocessed cashew kernels with CNSL residue on them would be dangerous to eat. The steam-boiling or roasting step that makes shelling possible also neutralizes most of the caustic oil. So the “raw” label is a marketing distinction between “steamed but not roasted” and “steamed and then roasted.” No cashew reaches a consumer without having been heated at least once.

This is also why cashews tend to cost more than almonds, peanuts, or walnuts at the store. The multi-step processing, the need for thermal treatment, the manual labor, and the low tolerance for breakage all add cost. The economic math is straightforward for processors, though: value-added cashew kernels deliver a positive return, with benefit-cost ratios around 1.4 to 1 and rates of return near 37 to 38%.¹⁴ The margins are thin, however, and variable costs make up over 96% of total processing costs, which means any disruption in labor, energy, or raw nut supply squeezes processors hard.¹⁴

Diseases and Pests That Threaten Orchards

Cashew trees face a range of diseases that affect stems, leaves, flowers, and nuts. Among the most economically damaging are anthracnose, caused by the fungal complex Colletotrichum gloeosporioides, and inflorescence blight caused by Lasiodiplodia theobromae.¹⁵ Anthracnose shows up as dark spots on leaves, sunken lesions on the apple, and blight on flowers and twigs. Surveys of cashew orchards in Ghana found anthracnose incidence averaging around 23% in infected orchards.¹⁶

Insect pests add another layer of pressure. In Nigeria, the stem borer Analeptes trifasciata is a major threat, with surveys showing yield losses of up to about 55% in affected areas.¹⁵ The wide host range and endophytic nature of some pathogens like Lasiodiplodia make disease management strategies especially challenging, since the fungus can live inside the tree’s tissues without causing symptoms until conditions favor an outbreak.

How Climate Change Is Reshaping Cashew Geography

Climate projections paint a mixed picture for cashew production. Globally, areas of high suitability for cashew cultivation are projected to increase by about 17%, largely because rising minimum temperatures in currently-too-cold regions will open up new land.¹⁷ New regions likely to become suitable include parts of southern Brazil, East Africa around Lake Victoria, northern India, southern China, and even parts of the southern United States and Australia.

But the gains are not evenly distributed. Current major producing regions in West Africa, Central America, and Southeast Asia face declining suitability as annual temperatures climb too high. Nigeria, a major producer, is among the countries projected to see negative shifts. Parts of Sri Lanka, the Philippines, Indonesia, and Cambodia could also become less hospitable.¹⁷ Modeling for Togo specifically found that under more aggressive warming scenarios, areas of very favorable cashew production could shrink dramatically or disappear entirely by 2050.¹⁸

The net result is that cashew production may shift geographically over the coming decades, with some traditional growing regions losing ground while new ones emerge. For smallholder farmers in West Africa and Southeast Asia who depend on cashew income, adaptation will mean either developing heat-tolerant varieties or transitioning to other crops. For consumers, it may eventually mean shifts in where the cashews on their shelves actually originate.

1
PubMed Central. Cashew nut and cashew apple: a scientific and technological monitoring worldwide review
2
Springer Link. Cashew: History, Evolutionary Origin, Genetic Resources, Improvement and Advances in Breeding
3
PubMed Central. The Cashew Pseudofruit (Anacardium occidentale): Composition, Processing Effects on Bioactive Compounds and Potential Benefits for Human Health
4
PubMed Central. Anacardic Acid Constituents from Cashew Nut Shell Liquid: NMR Characterization and the Effect of Unsaturation on Its Biological Activities
5
Scientific Reports. Cashew nutshell liquid derivatives as a sustainable route to alkyd-free surface coatings
6
Journal of the Saudi Society of Agricultural Sciences. Pre-shelling parameters and conditions that influence the whole kernel out-turn of steam-boiled cashew nuts
7
International Journal Semiarid. MINI SEMI-AUTOMATIC SHELLING MACHINE: A POSSIBILITY FOR CASHEW SHELLING
8
Journal of the Science of Food and Agriculture. Optimisation of processing conditions for infrared drying of cashew kernels with testa
9
PubMed Central. Occupational Health Problems among Workers of Cashew Processing Units in Kollam District, Kerala
10
Indian Journal of Health Sciences and Biomedical Research. Occupational safety and health hazards among cashew processing workers of Cuddalore district: A cross-sectional study
11
PubMed Central. Nutritional composition of raw fresh cashew (Anacardium occidentale L.) kernels from different origin
12
Croatian journal of food science and technology. Nutritional profile, protein quality, and biological value of raw and roasted cashew kernels (Anacardium occidentale) grown in southwest Nigeria
13
Journal of Food Science & Nutrition. Nutritional Value and Health Benefits of Cashew Nuts
14
PubMed Central. Economic viability of value-added cashew products processed in Southeast zone, Nigeria
15
Academic Press. Dynamics of diseases and insect pests of cashew tree
16
European Journal of Agriculture and Food Sciences. Colletotrichum Gloeosporioides Species Complex: Pathogen Causing Anthracnose, Gummosis and Die-Back Diseases of Cashew (Anacardium Occidentale L.) In Ghana
17
PLOS ONE. Expected global suitability of coffee, cashew and avocado due to climate change
18
Journal of Geography, Environment and Earth Science International. Identification of Potential Future Areas for Sustainable Cashew (Anacardium occidentale L.) Nut Production in Togo Using the Maxent Model