Baru nut

The baru tree is a tall, semi-deciduous tree of the savanna known as the Cerrado, bearing large clusters of flat, oval, brown fruits that look a bit like small, dry mangoes. Each fruit has a thin, sweetish pulp around a very hard stony shell, which holds a single dark, glossy, elongated seed.

The kernel is brown and about the size of a large peanut or a small almond, with a crisp texture and a roasted flavour somewhat between peanut and cashew.

It is sold shelled and roasted, salted or unsalted, as pieces in granola, as paste and as pressed oil, and the pulp is also made into flour.

Dipteryx alata is native to the Cerrado of central Brazil and extends into neighbouring parts of Bolivia and Paraguay. The tree grows in seasonal savanna woodland and has been gathered by indigenous and rural communities for generations.

It has not been domesticated in a formal sense, though its use is widespread, and farmers often leave baru trees standing in pastures for their shade and fruit.

The name baru comes from a Tupi-derived word used locally in Brazil. The genus Dipteryx is related to the tonka bean tree, the source of coumarin-rich tonka seeds.

The people of the Cerrado have long used baru as a seasonal food. Fruits ripen in the dry season and fall to the ground, where animals such as bats, monkeys and cattle eat the pulp, and where communities gather the stony fruits to crack them by hand.

For much of the 20th century baru was almost unknown outside its region, while the Cerrado itself was being converted at a fast rate to soy fields and pasture. Researchers at Brazilian universities and the agricultural research agency Embrapa began studying its nutritional value in the 1990s and 2000s.

Cooperatives of rural women and smallholders then developed a trade in processed baru nuts, with support from NGOs, which gave an economic incentive to conserve remaining Cerrado vegetation. Today, baru is promoted in Brazil as a sociobiodiversity product, sold in supermarkets, and exported in small volumes to Europe and North America as a novel snack nut.

Baru nuts are eaten roasted as a snack, chopped into granola and chocolate, ground into a paste similar to peanut butter, or used in pastries, ice cream and savoury Brazilian dishes such as farofa.

The fruit pulp is dried and ground into a sweetish flour used in baking and porridges, and the oil is used both for cooking and in cosmetics. In traditional Cerrado medicine, the oil and seeds have been used in home remedies, though this is not well-tested.

The hard shells are used as fuel and for craft work, and the wood of the tree is dense and long-lasting.

Baru kernels are reported to be rich in protein, unsaturated fat and dietary fibre, as well as minerals such as potassium, zinc and iron. Small human studies have examined the effect of regular baru consumption on cholesterol and blood sugar, with some encouraging but not conclusive results.

Roasting reduces anti-nutritional compounds present in the raw seed, which is why the nuts are always sold roasted.