Cashew

• 1. Introduction

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  The largest cashew tree in the world stands in Parnamirim, Brazil, and its canopy covers around 7500 square metres. That is a single plant of the species Anacardium occidentale, a tropical evergreen native to South America. Most people never see one. They meet the cashew as a curved, pale snack in a bowl. Yet that snack comes from a seed locked inside a shell that irritates the skin. It hangs below a swollen, colourful structure that most eaters have never tasted. This documentary asks a few simple questions. What is the fruit of a cashew tree, if the nut is not quite a nut? Why does its shell demand such careful handling? And how did a South American tree come to supply kitchens, distilleries and factories on several continents?

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• 2. A Nut Outside the Fruit

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  Cashew flowers open pale green and slowly turn reddish. They grow in a cluster, called a panicle or corymb, that can stretch up to 26 cm long. Each bloom is small, with five slender petals. The tree behind them is a leathery-leaved evergreen with a short trunk, often irregular in shape, and it can reach 14 m in height. Its leaves spiral around the twig and have smooth edges.

  What most people picture as the fruit is not the true fruit at all. The oval or pear-shaped body is called a hypocarpium, and it grows from the flower's pedicel and receptacle. Botanists call it an accessory fruit, or a false fruit. In Central America it is better known as marañón. It ripens to yellow or red.

  The real fruit hangs at the tip of that body. It is a drupe shaped like a kidney or a boxing glove. The order of growth is surprising. The drupe appears on the tree first. Only afterward does the pedicel swell into the apple. Inside the drupe sits a single seed, and cooks treat that seed as a nut. Around it lies a double shell, and what that shell holds explains why cashews almost never reach shoppers still wrapped in it.

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• 3. The Hazardous Shell

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  Inside the double shell of the cashew drupe lies a phenolic resin called anacardic acid. It is a potent skin irritant. Chemically, it is a cousin of urushiol, the toxic oil found in poison ivy and in the lacquer tree. Handling the shell can bring on contact dermatitis much like poison ivy does. The phenolic lipids, anacardic acids and cardanol drive that reaction. Raw seed is toxic too. The nut becomes safe to eat only after it is shelled and roasted or steamed.

  Eating cashews carries a separate risk. Up to 6% of children and 3% of adults may react to them. Symptoms range from mild discomfort to life-threatening anaphylaxis. Cashews trigger allergy less often than peanuts or other tree nuts. The trigger is the protein in the nut, and cooking often leaves that protein unchanged. Reactions can also follow hidden ingredients or stray traces picked up during processing.

  The oil in the shell, called cashew nutshell liquid, is a yellowish resin found in the shell's honeycomb structure. Processors get it as a byproduct. It must never be confused with the edible oil pressed from the nuts. Handling it in small-scale shell processing is dangerous. Even so, folk medicine in the tropics uses it, and it protects timber against termites.

  In industry, the liquid is a raw material with a chemistry of its own. Cold, solvent-extracted liquid is mostly anacardic acids, at 70%, with 18% cardol and 5% cardanol. Heating it strips a carbon group from the anacardic acids. The result is a technical grade rich in cardanol. Distilling that grade gives a liquid with 78% cardanol and 8% cardol. Cardanol goes into resins, coatings and friction materials. Chemists also turn it into polyols for rigid polyurethanes, prized partly for their natural fire-retardant behaviour. A related product, a novolac, serves as a hardener for epoxy in carbon composites. Shell derivatives also appear in paints. A black shell oil works as a preservative and waterproofing agent in varnishes and cement, and as a lubricant or timber seal.

  The thin reddish-brown husk around the kernel makes up about 5% of the nut. It is finding emerging uses as an adsorbent and in composites, biopolymers, dyes and enzyme synthesis. Cardanol, easy and cheap to extract from waste shells, is now under research for nanomaterials and biotechnology.

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• 4. Names and Voyages

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  The word cashew began as caju, the Portuguese name for the fruit, also written acaju. Portuguese borrowed it from the Tupi word acajú, which literally means nut that produces itself. That phrase fits a tree whose seed hangs outside its own fruit.

  The scientific name has a stranger history. Anacardium combines the Greek prefix ana-, the Greek cardia, and the Neo-Latin ending -ium. It may point to the heart shape of the fruit, to the top of the fruit stem, or to the seed. The word was first used for Semecarpus anacardium, the marking nut tree. Carl Linnaeus later moved the name to the cashew. Both plants belong to the same family. The species name occidentale refers to the Western, or Occidental, world.

  Portuguese explorers carried the tree out of South America during the 1500s. Colonists in Brazil were exporting cashew nuts as early as the 1550s. Between 1560 and 1565, the Portuguese took the tree to Goa, then called Estado da Índia Portuguesa. From Goa it spread through Southeast Asia and eventually reached Africa. Each new region was warm enough for it, and that tolerance of heat still decides where orchards stand.

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• 5. Orchards and Markets

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  Commercial cashew growing sits between 25°N and 25°S. The tree does best in hot lowlands with a pronounced dry season. Mango and tamarind trees thrive in the same conditions.

  The traditional tall tree is slow. It takes three years from planting to begin producing and eight years before harvests pay. Its yield is about 0.25 MT per hectare. Dwarf cultivars changed the arithmetic. They grow up to 6 m, start producing after the first year, and give economic yields after three. A dwarf orchard can top a ton per hectare. Grafting and other modern tree management help sustain those yields.

  In 2023, the world harvested about 3.9 million tonnes of cashew nuts. The Ivory Coast and India led, together supplying 46% of the total.

  Value depends on where the shelling happens. Almost all cashews grown in Africa between 2000 and 2019 left the continent as raw nuts, which sell for much less than shelled ones. The African Cashew Alliance has set out to promote African processing so that more of the profit stays local. At the retail end, the American chain Costco is reported to have sold half of the world's cashews as of 2025.

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• 6. Kitchens Around the World

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  A 100-gram portion of raw cashews provides 553 kilocalories. By weight, the raw nut is 5% water, 30% carbohydrate, 44% fat and 18% protein. It is rich in copper, manganese, phosphorus and magnesium, which supply 79-110% of the daily value. Thiamin, vitamin B6 and vitamin K supply 32-37%. Iron, potassium, zinc and selenium are present in significant amounts, at 14-61%. The same portion holds 113 mg of beta-sitosterol.

  In Indian cooking, cashews garnish sweets and curries. Ground into a paste, they form the base of sauces such as korma, and of sweets such as kaju barfi. Powdered cashew also goes into many desserts. Goan cooks use both roasted and raw kernels of Goa Kaju whole in curries and sweets. Thai and Chinese cooks generally keep the nut whole.

  The Philippines has its own traditions. Cashew is a known product of Antipolo, where it is eaten with suman. In Pampanga, a dessert called turrones de casuy wraps cashew marzipan in white wafers. In Indonesia, roasted and salted cashews are called kacang mete or kacang mede.

  In Mozambique, a cake named bolo polana is built on powdered cashews and mashed potatoes. It is also common in South Africa. In the 21st century, several African countries expanded cashew growing to meet demand for cashew milk, a plant-based alternative to dairy milk.

  Pressing the nuts yields a dark yellow oil, used for cooking or salad dressing. It usually comes from lower-value broken pieces created accidentally during processing. The best oil comes from a single cold pressing.

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• 7. The Perishable Apple

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  In Goa, ripe cashew apples are mashed, and the extracted juice, called neero, is left to ferment for a few days. Double distillation turns it into feni, a spirit of about 40-42% alcohol, or 80-84 proof. A single distillation gives urrak, at about 15%, or 30 proof. Across the Indian Ocean in Tanzania, the apple is called bibo in Swahili. It is dried, reconstituted with water, fermented and distilled into a strong liquor called gongo.

  The apple has gentler uses too. It can be eaten fresh or cooked in curries. It is made into vinegar, citric acid, preserves, chutneys and jams, notably in India and Brazil. In Brazil the juice and pulp go into sweets, and the juice is mixed with the sugarcane spirit cachaça. Brazilians also make flour, milk and cheese from it. Panama cooks the fruit with water and sugar for a long time to make dulce de marañón, a sweet, brown, paste-like dessert. Cajuína is a blended juice made from the apple. In Indonesia the fruit is called jambu monyet, literally monkey rose apple.

  The apple is astringent, and cooks have two remedies. Steaming it for five minutes before a cold wash removes the bite. So does steeping it in boiling salt water for five minutes. Even so, the apple bruises easily and keeps poorly, which is why the nut is traded far more widely.

  In Cambodia the tree is usually grown as an ornamental rather than a crop. There the fruit is a delicacy, eaten with salt. The bark yields a yellow dye, and the timber goes into boats and house-boards. The wood also makes excellent charcoal. Elsewhere timber becomes furniture and packing crates. Livestock can eat the leaves, and the residue left after oil extraction can be fed to animals. Leftover nuts unfit for people go to animals as well. The apple's juice turns black when it meets air, and that property makes it an indelible ink.

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