Brazil nut

Related species
Description and phenology
Distribution, abundance and ecology
Uses and economic potential
Historical production data
Miscellaneous information
Collection methods and yields
Propagation and cultivation methods
Research contacts

Charles R. Clement

Family: Lecythidaceae

Species: Bertholletia excelsa Humb. & Bonpl.

Synonyms: B. nobilis Miers.

Common names: Castanha do Pará, castanha do Brasil, castanheira (Brazil); castaña Brasileña, castaña (Bolivia, Peru); Brazil nut (English).

Related species

Bertholletia is a monospecific genus. The closely related genus Lecythis contains several edible species, notably the sapucaia or paradise nut group of species, the most widespread of which is L. pisonis = L. usitata (Mori & Prance 1990a,b).

Lecythis pisonis Cambess. The sapucaia is a large tree, although smaller in stature than the Brazil nut, and native to the terra firma (dry uplands) and varzeas (white water floodplain terraces) of Amazônia and the southeastern transition zones to cerrado. Sapucaia fruit vary enormously in size, from about the size of a Brazil nut to 5-or more times that, although they contain about the same number of seed (10-25) (Mori & Prance 1990a). Although the seeds are generally reputed to have a better flavor than those of the Brazil nut, sapucaia is rarely found at market because the fruit capsule opens while on the tree, providing a feast for bats (which also disperse the seeds) and parrots and monkeys (which are seed predators), but leaving little for humans to collect. On the varzea the trees are frequently planted around dwellings and, being relatively isolated from the forest, escape from predators and provide humans with a chance to collect the seed (B. Nelson, INPA, pers. com.). Attempts to graft sapucaia onto Brazil nut and vice versa have failed, but sapucaia on itself takes well and provides a method for the selection of superior types and their propagation.

Description and phenology

The following description is paraphrased from Mori & Prance (1990b) and FAO (1986).

Brazil nuts are large trees, frequently canopy emergents attaining 50 m in height, with straight cylindrical unbranched trunks attaining 1-2.5 m in diameter at breast height, clothed in a rough gray-brown bark with conspicuous longitudinal fissures. The openly branched crown occurs at or above canopy level and may have a diameter of 20-30 m in an emergent. The leaves are simple and alternately arranged on the branches. The leathery leaf blade is oblong, 17-36 cm long by 6-15 cm wide, smooth on both surfaces, with an entire leaf margin, attached to a 2-3.5 cm long petiole. The flowers are born on axillary or terminal spikes, with one or two orders of branching, although it is rare that more than one flower per inflorescence mature into fruit. The flowers are 3-4 cm in diameter when fully opened, with 6 petals, each 3 cm long, of a pale yellow to creamy white color. The creamy white to yellow androecium forms a hood over the ovary, with an internal depression containing a ring of stamens, numbering 80-135. The androecial hood must be forced open by the large bees that pollinate it; these are attracted by nectar. The Brazil nut is an allogamous species, possibly presenting very small levels of autogamy (O'Malley et al. 1988, Buckley et al. 1988). The fruit are large (10-12 cm in both diameters), round capsules, with a hard woody capsule wall, weighing 0.5-2.5 kg, containing 10-25 seed. The seed are about 3.5-5 cm long by 2 cm wide, with a distinctly triangular cross section. Each seed weighs 4-10 g. The Brazil nut is, in fact, a seed rather than a nut, but popular usage continues to prevail.

The Brazil nut flowers during the dry season. In eastern Amazônia flowering starts at the-end of the rainy season (September) and extends to February, with the greatest intensity in October-December (Moritz 1984). In Manaus, flowering starts earlier because the dry season starts in June, and extends to August-September. The Brazil nut fruit takes 15 months to develop to maturity (Moritz 1984). Fruit fall, therefore, starts at the beginning of the rainy season. This is January to April in eastern Amazônia and November to March in the Manaus area.

Distribution, abundance and ecology

The Brazil nut may have originated in southeastern Amazônia (S. Mori, NYBG, pers. com.) from a Lecythis-like ancestor, similar to L. lurida (Miers) Mori (Mori & Prance 1990b). The seed is thought to be dispersed principally by agoutis (Dasyprocta sp.), small forest rodents, which are the only animals known to open the Brazil nut fruit and extract the seed. Some of the seed are consumed immediately, others are stored for later consumption or are forgotten and germinate (Mori & Prance 1990b). This seed dispersal mechanism must have severely limited the Brazil nut's original range, because viable seed would have great difficulty in crossing major river tributaries.

The arrival of humans in Amazônia probably changed the Brazil nut's distribution dramatically. Its evident food value, due to oils and protein, and flavor must have made it a preferred extractivist resource very early in the human occupation of Amazônia. Later, seed and perhaps seedlings were planted by Amerindians into suitable locations and into their developing agroecosystems. This practice continues among the Amerindians in southeastern Amazônia today (Posey 1985) and elsewhere in Amazônia among Amerindians, caboclos (mixed blood long-term natives) and modern colonists. Muller et al. (1980) suggest that most "natural" stands of the Brazil nut were created through Amerindian intervention. Agouti dispersal may then have completed the species' occupation of a new area.

Today the Brazil nut is found in most of Amazônia the adjacent Guaiana highlands and forested lowlands, and the upper Orinoco River basin. In Amazônia it is found in Brazil, French Guiana, Suriname, Guyana, southern Venezuela, southeastern Colombia, eastern Peru and northern Bolivia. There are some curious irregularities in its distribution that give support to Muller et al.'s (1980) hypothesis of Amerindian intervention as a means of distribution. The area around Manaus, although well populated at contact, was free of the Brazil nut until it was planted in historic times (Nelson et al. 1985). The Juruá River basin also appears to have had no Amerindian or agouti introduced Brazil nut until recently (B. Nelson, INPA, pers. com.). One can only assume that the Amerindian groups that occupied these areas did not consider the Brazil nut to be as delectable as other groups obviously did.

The Brazil nut occurs as a rare emergent or upper canopy component of the terra firma forest throughout much of this region, at an abundance of 1 tree or less per hectare, although occasionally occurring in stands. This suggests that Brazil nuts are gap dependent (Mori & Prance 1990b), which means that they only attain reproductive size when growing in a light gap created in the forest by the fall of a large tree or other disturbance. This type of abundance pattern is also compatible with agouti dispersal.

In numerous areas, however, the Brazil nut is found in castanhais (Brazil) or manchales (Peru). These are areas of high abundance, frequently attaining 15-20 mature trees/ha. This type of abundance pattern also supports Muller et al.'s (1980) hypothesis of Amerindian intervention in Brazil nut population dynamics and distribution. These castanhais frequently cover 510 ha or more and are separated from one another by 0.5-1 km or more, suggestive of the pattern of Amerindian exploitation of the forest environment with widely spaced swidden plots. In some areas of SE Pará and SE Acre states the castanhais may occupy 50100 ha areas. One of these large castanhais can be seen in Acre in a degrading pasture; unfortunately most of the trees had been killed by the periodic fires used to control weeds and enrich the soil in the pasture. This practice, while technically legal, is severely eroding the genetic resources of the species (Clement & Chavez 1983).

The Brazil nut is found principally on the nutrient-poor, well-structured and well-drained oxisols and ultisols of the terra firma. In eastern Amazônia especially, its taproot is known to penetrate 5-10 m into the soil and may penetrate much deeper (C.H. Muller, CPATU, pers. com.). It is not found in areas with poor drainage nor on excessively compacted soils.

Diniz & Bastos (1974) report that the Brazil nut is found in areas with a mean annual rainfall of 1400-2800 mm, a mean annual temperature of 24-27°C and a mean annual relative humidity of 79-86%. These ranges cover the "Ami", "Afi" and "Awl" climate regimes of Köppen, giving it an extremely wide climatic tolerance. In eastern Amazônia the mean rainfall and relative humidity are at or near the lower limits of the ranges mentioned, and the species is subjected to 2-7 months of water deficit (dry season = less than 100 mm rainfall/month). This climate regime is "Ami" in Köppen's scheme. As a consequence, Muller (1981) suggested that the Brazil nut requires two to five months of low rainfall to develop properly.

Uses and economic potential

Principal use
Secondary uses

Principal use

Brazil nuts are consumed raw, roasted, salted, in ice creams or as prepared confectionery items (Mori & Prance 1990b, Rosengarten 1984). They are an important ingredient in shelled nut mixtures (Rosengarten 1984). Woodroof (1979) presents 50 recipes for the Brazil nut, mostly for confectionery uses. Clark & Nursten (1976) analyzed the seed flavor components.

Table 1 presents the proximal composition of the Brazil nut kernel. Mori & Prance (1990b) cite Zucas et al. (1975) as reporting that Brazil nut protein contains all the essential amino acids, although without reporting which of may fall below FAD/WHO (1973) limits. They do report that Brazil nut protein has a lower nutritional value than casein, suggesting that some of the essential amino acids are limited. Table 2 presents the mineral composition and vitamin content of Brazil nut kernels (USDA 1975, cited by Rosengarten 1984).

Table 1. Proximal composition of the Brazil nut kernel.

¹. % fresh weight;
². % dry weight;
³. calories/100 g fresh weight;
⁴. N-free extract and fiber combined.

Table 2. Mineral composition (A) and vitamin content (B) of Brazil nut kernels (USDA 1975, cited by Rosengarten 1984).

¹. minerals in mg;
². Vitamin A in Intern'l Units;
³. other vitamins in mg

The nuts require considerable care in handling, because they are highly susceptible to bruising, molding and insect infestations (Woodroof 1979). Because of this, a relatively high proportion of nuts collected are later rejected by processing plants, which have traditionally been located in the major urban centers, hundreds of kilometers from the collection centers. As a result of molding, they may accumulate aflotoxins, which can cause the rejection of whole batches of nuts exported in-shell (FAO 1986). Because the nuts are very rich in oils, they rancify easily and may absorb foreign flavors, losing their own (Woodroof 1979).

Over the last decade, Brazil nut production has hovered around the 40,000 MT level, but could expanded easily if demand expanded. This additional production could come from the thousands of forest trees that are currently not harvested because of the low prices paid to most collectors. The low prices are due partially to slack international demand and partially to the number of middlemen involved in getting the nuts from the forest to the processing plants. The extractivist reserves now being set up in Acre, Pará and Rondônia are trying to organize local processing and cooperative commercialization so that a greater proportion of the end value of the nuts can be paid to the collectors, hopefully encouraging greater harvests while improving the collector incomes. Cultural-Survival's Rainforest Marketing Project is collaborating with the extractivists in Acre on this attempt.

Secondary uses

Brazil nut is considered to be amongst the finest timbers of Amazônia as it has a straight grain, is easy to work, takes a finish readily, has a pleasing appearance and is very durable (Loureiro et al. 1979). Although the felling of Brazil nut is prohibited by law in Brazil, there is thought to be a considerable black market for its wood (Mori & Prance 1990b). SUDAM (1979) concluded that it has superior silvicultural characteristics, including fast growth (more than 1 m/yr in the first decade), straight trunk, tolerance or resistance to pests and diseases in plantation. G. Hartshorn (WWF-US, pers. com.) has observed that Brazil nut can even be abandoned in second growth and still give excellent growth and trunk shape. This suggests that Brazil nut could be used to help restore degraded sites (100,000 km² in Amazônia as a multipurpose species, yielding nuts after 15-20 years and timber after 50-100.

As with most nuts, the Brazil nut is rich in oils, variously reported at 65-70% of seed dry weight (Pesce 1985, Woodroof 1979). This oil is rich in unsaturated fatty acids (75%) and may be attractive for various culinary uses (Woodroof 1979). Table 3 presents the fatty acid composition of the kernel fat (Woodroof 1979), with the percentages of insaturation, a highly relevant summation in modern dietary theory. Assunção et al. (1984) report on the stability of this oil. Nut" that are rejected for export could be pressed for oil, if a market is found. This would encourage quality control, now rather precarious in some processing plants, and increase the value of the nuts to the collectors.

One of the reasons frequently cited for conserving the Amazonian rainforest is to conserve the genes that make up its enormous specific and intraspecific diversity, since these are the raw materials for the biotechnology revolution now underway in the developed world. Brazil nut is an example of how this idea works.

Table 3. Fatty acid composition (%) of pressure extracted Brazil nut kernel fat (Adams 1975, cited by Woodroof 1979).

C14:0 = myristic; C16:0 = palmitic; C16:1 = palmitoleic; C18:0 = stearic; C18:1 = oleic; C18:2 = linoleic; C18:3 = linolenic; %IS = % insaturation = C16:1 + C18:1 + C18:2 + C18:3.

The Brazil nut is rich in sulfur amino acids (methionine, cysteine), which are deficient in the seed of the common bean (Phaseolus vulgaris), for example. Since the common bean is a major source of protein in the Third World, two laboratories (one in California, one in Brasilia) are racing to put Brazil nut amino acids into the bean (Gander 1986). The relevant gene has been isolated, inserted into the bean genome, and found to be expressed in bean callous tissue. Both laboratories are having some trouble regenerating the transgenic plants from callous and must then determine that the amino acid genes are expressed in the seed (B. Gander, CENARGEN, pers. com.). When the transgenic plants are finally grown out, they must then be bred conventionally to obtain cultivars suitable for distribution to farmers. Once this process is completed, the common bean will have nutritional characteristics much superior to those it now has and will become even more important a staple than it currently-is. The steps followed in this process to date can be traced in Altenbach et al. (1984), Ampe et al. (1986), Castro et al (1987), Guerche et al. (1990), Kamiya et al. (1983), Plietz et al. (1988), Sun et al. (1987ab).

Historical production data

Brazil nut entered world commerce in the late 18th century, introduced by Dutch traders during the period that they attempted to colonize eastern Amazônia and Maranhão (Mori & Prance 1990b). A prosperous trade developed soon after Brazil opened its ports to world trade in the late 19th century and Brazil nut has been an important item of trade since that period (ibid.). Before this, it had been an extremely important subsistence product for the Amerindians and later the colonists.

Figure 1 presents historical production data (IBGE, cited by Mori L Prance 1990b, plus more recent data). The historical production mean is close to 40,000 tons but could be much larger if there was sufficient demand (note 1970 production of 104,000 tons).

Figure 2 presents export data for the decade 1975-84 (CACEX 1976-85). Most exports during the period were in-shell (either raw or partially dehydrated), which results in a lower unit value for the product. The FOB value of shelled Brazil nut is generally at least twice that of the in-shell nut. Rosengarten (1984) noted that both in-shell and shelled nuts are now being packaged much more efficiently (see below). In fact, in-shell raw nuts disappeared from the CACEX registry during 1982-84, suggesting that at least that part of the in-shell exports is now being partially processed.

Miscellaneous information

It is frequently commented that Brazil nuts can cause hair loss if consumed in large quantities. This has, in fact, occurred, and is due to high concentrations of selenium. Thorn et al. (1978) report on the presence of selenium in Brazil nuts in England. Chansler et al. (1986) and Palmer et al. (1982) report on experimentally induced selenium toxicity in laboratory animals.

The reason that Brazil nut concentrates selenium is probably that this element is very, similar chemically to sulfur, an essential nutrient in seed protein (see section 5.2). Sulfur is frequently deficient in Amazonian soils, especially after decades or centuries of Brazil nut harvesting and export from the casthanais. If the soil contains significant amounts of selenium, this is used by the plant instead of sulfur. If selenium is not present, there is no problem, other than reduced yields, as sulfur becomes limiting.

A simple solution to the selenium problem is to fertilize the affected area with sulfur. This is commonly practiced by the caboclos along the Rio Madeira to improve yields (V. Cruz Alves, INPA, pers. com.), although there are no reports of selenium problems there. The caboclos use pharmaceutical sulfur, the only form available to them, and apply it in the following manner: they drill a small hole (approximately 1 cm in diameter) in the bark of the tree as far as the cambium layer; they then place 12 grams of sulfur into this hole; the hole is then closed with pitch or jatobá (Hymenaea courbaril) resin. If the sulfur is applied after the-flowering season, the following flowering season will result in significantly improved yields. This caboclo practice pointed to a solution to the selenium and low yield problems in older castanhais throughout Amazônia but no experimental work has been done to prove the validity of this theory.

Collection methods and yields

Rosengarten (1984) reports that a mature tree can yield 100-225, kg of unshelled nuts in a good year. The lower figure is probably close to an average yield on good soils, with adequate rainfall and low competition from other trees. No detailed experimental yield results exist. Based on Rosengarten's report and a monoculture plantation density of 100 seedling trees/ha, this yield is equivalent to 10 MT/ha/yr. It is emphasized that this is only a projection to allow comparison with other species. Rosengarten (1984) also points out that a good year is generally followed by a poor one, as the tree uses most of its accumulated reserves and takes more than a year to accumulate more. Alternate bearing is common in undomesticated species and will be one of the first traits modified by selection in the on-going Brazil nut improvement program executed by EMBRAPA's Agricultural Research Center for the Humid Tropics (CPATU).

Mori & Prance (1990b), Moritz & Ludders (1985), Rosengarten (1984) and Woodroof (1979) discuss collection and processing of the Brazil nut and describe the life and hard times of the castanheiros (the Brazil nut harvesters), so only a brief outline will be presented here.

The fruits are collected from the ground under wild trees during the rainy season, generally in the morning. Because of competition from agoutis, insects and fungus, the castanheiros visit the trees regularly. A good day of collecting will yield 700-800 fruit, containing 700-20,000 seed (the last figure is highly unlikely, however, and was derived from the multiplication of the highest collection figure by the highest seed number figure given previously). Collecting is a dangerous business because the heavy fruit fall from the 40-50 m high canopy at a great velocity and can cause serious injury or even death if they strike a person.

In the afternoon the fruit are opened, either with a machete or with an axe, and the seed removed. These are generally washed immediately, left to dry for a few hours and stored out of the rain. A conscientious castanheiro will sun dry his seeds for a few days and store them in a dry environment, although, with a relative humidity of 80% during the rainy season, this is still quite humid. This lack of adequate storage conditions in the castanhal is the major reason that seed quality is not very high when the castanheiro finally gets his harvest to market.

C.H. Muller (CPATU, pers. com.) has worked on solar sun driers and plastic bagging to store seed in the interior. While he has had moderate results, the realities of castanheiro economics have relegated these ideas to the library. The beginning of a cooperative enterprise in Acre and other Brazil nut regions could change this and allow the castanheiros to maintain quality and obtain a better price for their harvest.

Most castanheiros sell their harvest to intermediaries who cruise the interior during the harvest season. These merchants then cell to others or directly to a processing plant, generally located in a major urban center. Traditionally Manaus and Belém have been the major centers, although Rio Branco (Acre) has become important recently.

At the processing plant, the nuts are sorted, first by floating (as damaged and diseased nuts will generally float, while healthy nuts will sink), then by visual inspection. They may be graded at this stage or after shelling. If the nuts are to be shelled, they will be soaked for 8-24 hours in room temperature water. They are then dried, to shrink the kernel from the shell, and cracked open with a hand press. The shelled nuts are then graded by size and quality (tiny, midget, medium, large, chipped, broken).

Modern packaging involves placing graded, high-quality, shelled nuts into laminated plastic bags, which are vacuum-sealed (Rosengarten 1984). Nitrogen gas is then introduced into the package to further conserve quality. Bag sizes vary from 20 to 50 kg. These can be stored and shipped conveniently, although most product is shipped shortly after packaging and inventories are kept low.

With the advent of a cooperative system in Acre and elsewhere, it is possible to process and package Brazil nut close to the harvest area. This is also a part of Cultural Survival's Rainforest Marketing Project and is the best way to add value for forest-extracted Brazil nuts. The alternative is plantations, which are already being installed in several areas. To support the. rainforest peoples and conserve significant areas of tropical forest, however, an extractivist system of forest management appears to be feasible if it is combined with on-site processing and direct marketing. These two factors eliminate most of the middlemen currently involved and allow the castanheiros to receive a greater percentage of the final value of the nuts. Without this, the castanheiro has little or no incentive to expand, or sometimes even to continue, harvesting. When this happens the fate of the forest is left to the next colonist, which generally means chain saws and fire.