Cashew

The cashew tree is an evergreen that reaches about ten to fourteen metres. Its odd fruit has two parts: a fleshy, pear-shaped, yellow or red stalk called the cashew apple, and below it a grey, kidney-shaped shell that contains the single seed, the cashew nut. The shell wall holds a caustic oil that can burn skin, so the nuts cannot be shelled by hand without protection.

The kernel is curved, ivory in colour and has a mild, sweet, buttery taste with a soft crunch. Cashews are sold raw, roasted, salted, as pieces, as butter, as a flour and as the base of vegan creams and cheeses. The cashew apple is eaten fresh or turned into juice and spirits in producing regions.

The cashew is native to northeastern Brazil, in the dry coastal areas of the region. Indigenous Tupi people knew the tree as acaju, from which the Portuguese caju and the English cashew are derived. The genus name Anacardium refers to the shape of the fruit, with ana meaning upwards and cardium heart.

Portuguese colonists carried cashew trees from Brazil to their colonies in India in the sixteenth century, planting them first around Goa, and to Mozambique and Tanzania in East Africa, where they were originally used to prevent soil erosion. Cashew then spread across tropical Asia and Africa.

The Tupi of coastal Brazil ate the cashew apple and roasted the nut long before Europeans arrived. Portuguese explorers noted the tree and carried it to their trading posts. In Goa the cashew thrived and became a permanent part of the cuisine, with cashew apple used to make the spirit feni.

For centuries the nut was a local curiosity because of the difficulty of removing the shell and its caustic liquid. Industrial processing, first developed in India in the twentieth century, made cashews an international commodity. Workers traditionally shelled nuts by hand, and the process remains labour-intensive, often performed by women, with health and wage concerns in some producing areas.

Today, Vietnam, India, Cote d'Ivoire, Tanzania and other African nations grow most of the world's cashews. The shell liquid, known as cashew nutshell liquid, has industrial uses in resins, coatings and brake linings. Plant-based foods have driven growth in demand, since soaked cashews blend into smooth creams.

Cashews are eaten roasted and salted as a snack, tossed into stir-fries and curries, ground into pastes that thicken sauces in Indian dishes such as korma, and blended into creams, cheeses and ice cream alternatives. Cashew butter and milk are used in vegan cooking.

In Goa and Brazil the juicy cashew apple is eaten fresh, made into juice, preserves and spirits such as feni. In Indian sweets, cashew paste is shaped into kaju katli. The shell oil is used industrially, and in traditional medicine the bark, leaves and apples have been used for various minor ailments.

Cashews supply mostly unsaturated fats, plant protein, magnesium, copper, zinc and iron. Studies of nut consumption in general, including cashews, link regular intake with modest improvements in blood lipids and heart health when nuts replace less healthy snacks.

They are energy dense, so portion size matters, and salted or oil-roasted versions add sodium and extra fat. Cashews are relatively high in oxalate, which is relevant to people prone to kidney stones.