| Brazil nut tree | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Ericales |
| Family: | Lecythidaceae |
| Genus: | Bertholletia Bonpl. |
| Species: | B. excelsa |
| Binomial name | |
| Bertholletia excelsa Humb. & Bonpl. | |
Brazil nut (Bertholletia excelsa) refers to aSouth Americantree in the familyLecythidaceae as well as the tree's commercially-harvested edibleseeds.[2] It is one of the largest and longest-lived trees in theAmazon rainforest. The fruit and itsnutshell – containing the ediblenut – are relatively large and weigh as much as 2 kg (4.4 lb) in total. As food, Brazil nuts are notable for diverse content ofmicronutrients, especially a high amount ofselenium. The wood of the Brazil nut tree is prized for its quality incarpentry,flooring, and heavy construction.
In 2023,Brazil andBolivia combined produced 91% of the world total of Brazil nuts.
In Portuguese-speaking countries, like Brazil, they are variously called "castanha-do-brasil"[3][4] (meaning "chestnut from Brazil" in Portuguese), "castanha-do-pará" (meaning "chestnut fromPará" in Portuguese), castanha-da-amazônia,[5] castanha-do-acre,[6] "noz amazônica" (meaning "Amazonian nut" in Portuguese), noz boliviana, tocari (probably of Carib origin[7]), and tururi (fromTupituru'ri[8]).[2]
In various Spanish-speaking countries ofSouth America, Brazil nuts are calledcastañas de Brasil,nuez de Brasil, orcastañas de Pará (or Para).[2][9]
In North America, as early as 1896, Brazil nuts were sometimes known by theslang term "nigger toes",[10][11][12] avulgarity that fell out of use after theracial slur became moresocially unacceptable.[13][14]
The Brazil nut is a large tree, reaching 50 metres (160 feet) tall,[15] with a trunk 1 to 2 m (3 to 7 ft) indiameter, making it among the largest of trees in theAmazon rainforest. It may live for 500 years or more, and can often reach a thousand years of age.[16] Thestem is straight and commonly without branches for well over half the tree's height, with a large, emergent crown of long branches above the surrounding canopy of other trees.
The bark is grayish and smooth. The leaves are dry-seasondeciduous, alternate, simple, entire or crenate, oblong, 20–35 centimetres (8–14 in) long, and 10–15 cm (4–6 in) broad. The flowers are small, greenish-white, inpanicles 5–10 cm (2–4 in) long; each flower has a two-parted, deciduouscalyx, six unequal cream-colored petals, and numerousstamens united into a broad, hood-shaped mass.[citation needed]
Brazil nut trees produce fruit almost exclusively in pristine forests, as disturbed forests lack the large-bodied bees of the generaBombus,Centris,Epicharis,Eulaema, andXylocopa, which are the only ones capable ofpollinating the tree's flowers, with different bee genera being the primary pollinators in different areas, and different times of year.[17][18][19] Brazil nuts have been harvested from plantations, but production is low and is currently not economically viable.[2][15][20]
The fruit takes 14 months to mature after pollination of the flowers. The fruit itself is a largecapsule 10–15 cm (4–6 in) in diameter, resembling a coconutendocarp in size and weighing up to 2 kg (4 lb 7 oz). It has a hard, woody shell 8–12 mm (3⁄8–1⁄2 in) thick, which contains eight to 24 wedge-shaped seeds4–5 cm (1+5⁄8–2 in) long (the "Brazil nuts") packed like the segments of an orange, but not limited to one whorl of segments. Up to three whorls can be stacked onto each other, with the polar ends of the segments of the middle whorl nestling into the upper and lower whorls (see illustration above).
The capsule contains a small hole at one end, which enables large rodents like theagouti to gnaw it open.[21] They then eat some of the seeds inside while burying others for later use; some of these are able to germinate into new Brazil nut trees.[21] Most of the seeds are "planted" by the agoutis incaches duringwet season,[21] and the young saplings may have to wait years, in a state of dormancy, for a tree to fall and sunlight to reach it, when it starts growing again.
The Brazil nut family, the Lecythidaceae, is in the orderEricales, as are other well-known plants such as blueberries, cranberries,sapote,gutta-percha,tea,phlox, andpersimmons. The tree is the only species in themonotypic genusBertholletia,[2] named after French chemistClaude Louis Berthollet.[22]
The Brazil nut is native to theGuianas,Venezuela,Brazil, easternColombia, easternPeru, and easternBolivia. It occurs as scattered trees in large forests on the banks of theAmazon River,Rio Negro,Tapajós, and theOrinoco. The fruit is heavy and rigid; when the fruits fall, they pose a serious threat to vehicles and potential fortraumatic brain injury of people passing under the tree.[23]
Capuchin monkeys have been reported to open Brazil nuts using a stone as ananvil.[citation needed]
 Brazil | 35,351 |
 Bolivia | 33,650 |
 Peru | 6,909 |
| World | 75,910 |
| Source:FAOSTAT of theUnited Nations[24] | |
In 2023, world production of Brazil nuts (in shells) was 75,910tonnes, most of which derive from wild harvests in tropical forests, especially theAmazon regions of Brazil and Bolivia which together produced 91% of the total (table).
Since most of the production for international trade is harvested in the wild,[25][26] the business arrangement has been advanced as a model for generating income from atropical forest without destroying it.[25] The nuts are most often gathered by migrant workers known ascastañeros (inSpanish) orcastanheiros (inPortuguese).[25]Logging is a significant threat to the sustainability of the Brazil nut-harvesting industry.[25][26]
Analysis of tree ages in areas that are harvested shows that moderate and intense gathering takes so many seeds that not enough are left to replace older trees as they die.[26] Sites with light gathering activities had many young trees, while sites with intense gathering practices had nearly none.[27]
Brazil nuts are susceptible to contamination byaflatoxins, produced by fungi, once they fall to the ground.[28] Aflatoxins can causeliver damage, including possible cancer, if consumed.[29] Aflatoxin levels have been found in Brazil nuts during inspections that were far higher than the limits set by the EU.[30] However, mechanical sorting and drying was found to eliminate 98% of aflatoxins; a 2003 EU ban on importation[29] was rescinded after new tolerance levels were set.
The nuts may contain traces ofradium, aradioactive element, with a kilogram of nuts containing an activity between 40 and 260becquerels (1 and 7nanocuries). This level of radium is small, although higher than in other common foods. According toOak Ridge Associated Universities, elevated levels of radium in the soil does not directly cause the concentration of radium, but "the very extensive root system of the tree" can concentrate naturally occurring radioactive material, when present in the soil.[31] Radium can be concentrated in nuts only if it is present in the soil.[32]
Brazil nuts also containbarium, a metal with a chemical behavior quite similar to radium.[33] While barium can have toxic side effects when ingested (weakness, vomiting, diarrhea, etc.)[34] the amount present in Brazil nuts is too small to have noticeable health effects.
In 2003, the European Union imposed strict regulations on the import of Brazilian-harvested Brazil nuts in their shells, as the shells are considered to contain unsafe levels of aflatoxins, a potential cause ofliver cancer.[29]
| Nutritional value per 100 g (3.5 oz) | |||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Energy | 2,743 kJ (656 kcal) | ||||||||||||||||||||||||||||||||||||||||||||||||
12.27 g | |||||||||||||||||||||||||||||||||||||||||||||||||
| Starch | 0.25 g | ||||||||||||||||||||||||||||||||||||||||||||||||
| Sugars | 2.33 g | ||||||||||||||||||||||||||||||||||||||||||||||||
| Dietary fiber | 7.5 g | ||||||||||||||||||||||||||||||||||||||||||||||||
66.43 g | |||||||||||||||||||||||||||||||||||||||||||||||||
| Saturated | 15.137 g | ||||||||||||||||||||||||||||||||||||||||||||||||
| Monounsaturated | 24.548 g | ||||||||||||||||||||||||||||||||||||||||||||||||
| Polyunsaturated | 20.577 g | ||||||||||||||||||||||||||||||||||||||||||||||||
14.32 g | |||||||||||||||||||||||||||||||||||||||||||||||||
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| Other constituents | Quantity | ||||||||||||||||||||||||||||||||||||||||||||||||
| Water | 3.48 g | ||||||||||||||||||||||||||||||||||||||||||||||||
| Selenium | 1917 μg | ||||||||||||||||||||||||||||||||||||||||||||||||
| Beta-sitosterol | 64 mg | ||||||||||||||||||||||||||||||||||||||||||||||||
| †Percentages estimated usingUS recommendations for adults,[35] except for potassium, which is estimated based on expert recommendation from theNational Academies.[36] | |||||||||||||||||||||||||||||||||||||||||||||||||
Brazil nuts are 3% water, 14%protein, 12%carbohydrates, and 66%fats. The fat components are 16%saturated, 24%monounsaturated, and 24%polyunsaturated.[37]
In a 100 grams (3.5 ounces) reference amount, Brazil nuts supply 659calories, and are a rich source (20% or more of theDaily Value, DV) ofdietary fiber (30% DV),thiamin (54% DV),vitamin E (38% DV),magnesium (106% DV),phosphorus (104% DV),manganese (57% DV), andzinc (43% DV).Calcium,iron, andpotassium are present in moderate amounts (10–19% DV).
Brazil nuts are a particularly rich source ofselenium, with just 28 g (1 oz) supplying 544micrograms of selenium or 10 times the DV of 55 micrograms.[37][38] However, the amount of selenium within batches of nuts may vary considerably.[39]
The high selenium content is used as abiomarker in studies of selenium intake and deficiency.[40][41] Consumption of just one Brazil nut per day over 8 weeks was sufficient to restore selenium blood levels and increaseHDL cholesterol in obese women.[41]
Brazil nutoil contains 48%unsaturated fatty acids composed mainly ofoleic andlinoleic acids, thephytosterol,beta-sitosterol,[42] and fat-solublevitamin E.[43]
The following table presents the composition of fatty acids in Brazil nut oil:[37]
| Palmitic acid | 10% |
| Palmitoleic acid | 0.2% |
| Stearic acid | 6% |
| Oleic acid | 24% |
| Linoleic acid | 24% |
| Alpha-linolenic acid | 0.04% |
| Saturated fats | 16% |
| Unsaturated fats | 48% |
Thelumber from Brazil nut trees (not to be confused withBrazilwood) is of excellent quality, having diverse uses from flooring to heavy construction.[44] Logging the trees is prohibited by law in all three producing countries (Brazil, Bolivia, and Peru). Illegal extraction of timber and land clearances present continuing threats.[45] In Brazil, cutting down a Brazil nut tree requires previous authorization from theBrazilian Institute of Environment and Renewable Natural Resources.[46][47]
Brazil nut oil is used as alubricant in clocks[48] and in the manufacturing of paint andcosmetics, such as soap and perfume.[44] Because of its hardness, the Brazil nutshell is often pulverized and used as an abrasive to polish materials, such as metals and ceramics, in the same way asjeweler's rouge, whilecharcoal from the shells can be used to purify water.[44]
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