| Açaí palm | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Monocots |
| (unranked): | Commelinids |
| Order: | Arecales |
| Family: | Arecaceae |
| Genus: | Euterpe |
| Species: | E. oleracea |
| Binomial name | |
| Euterpe oleracea Mart. |
|
The açaí palm (Portuguese: [aˌsaˈi] ( listen)) (Euterpe oleracea) is a species of palm tree in the genus Euterpe cultivated for their fruit and superior hearts of palm. Its name comes from the Portuguese adaptation of the Tupian word ïwaca'i, '[fruit that] cries or expels water'. Global demand for the fruit has expanded rapidly in recent years, and açaí is now cultivated for that purpose primarily. The closely related species Euterpe edulis (juçara) is now predominantly used for hearts of palm.
Eight species are native to Central and South America, from Belize southward to Brazil and Peru, growing mainly in swamps and floodplains. Açaí palms are tall, slender palms growing to 15–30 meters, with pinnate leaves up to 3 meters long.
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The fruit, a small, round, black-purple drupe about 1 inch (25 mm) in circumference, similar in appearance but smaller than a grape and with less pulp, is produced in branched panicles of 500 to 900 fruits. The exocarp of the ripe fruits is a deep purple color, or green, depending on the kind of açaí and its maturity. The mesocarp is pulpy and thin, with a consistent thickness of 1 mm or less. It surrounds the voluminous and hard endocarp, which contains a single large seed about 0.25–0.40 inches (7–10 mm) in diameter. The seed makes up about 80% of the fruit (Schauss, 2006c). Two crops of fruit are produced each year. The fruits can be harvested and consumed.
In a study of three traditional Caboclo populations in the Brazilian Amazon, açaí palm was described as the most important plant species because the fruit makes up a major component of their diet, up to 42% of the total food intake by weight.[1]
In the northern state of Pará, Brazil, açaí pulp is traditionally served in gourds called "cuias" with tapioca and, depending on the local preference, can be consumed either salty or sweet (sugar, rapadura, and honey are known to be used in the mix). Açaí has become popular in southern Brazil where it is consumed cold as açaí na tigela ("açaí in the bowl"), mostly mixed with granola. Açaí is also consumed in Brazil as an ice cream flavor or juice. The juice has also been used in a flavored liqueur.
Today, a half-dozen brands market açaí in the beverage space.[2] Although most açaí is grown conventionally, the US company Sambazon established USDA Organic certification for their açai palm plantations in 2003 and has also implemented fair trade certification.[3]
In 2005, an article published by Greenpeace International stated that “the tasty dark violet wine of açaí is the most important non-wood forest product in terms of money from the river delta of the Amazon.” [4] In 2008, the Los Angeles Times reported that açaí is a renewable resource that can provide a sustainable livelihood for subsistence harvesters without damaging the Amazon Rainforest. The Times noted that wild harvesting of açaí may contribute to forest preservation and support of harvesting families, thereby making the forest more economical intact rather than cut down. While conventionally grown, monoculture açaí farming is a threat to the rainforest, açaí has been used to successfully reforest already degraded regions.[5] In May 2009, Bloomberg reported that the expanding popularity of açaí in the United States was "depriving Brazilian jungle dwellers of a protein-rich nutrient they’ve relied on for generations."[6]
In the regions of açaí production, such as Pará, açaí palms have replaced sugar cane and other cultivation choices more damaging to the natural environment, such as cattle farming. Such practices indicate that systematic cultivation and reliable commercial supplies may be more prevalent.
Apart from the use of its fruit as food or beverage, the açaí palm has other commercial uses. Leaves may be made into hats, mats, baskets, brooms and roof thatch for homes, and trunk wood, resistant to pests, for building construction.[7] Tree trunks may be processed to yield minerals.[8] The palm heart is widely exploited as a delicacy.[9]
Comprising 80% of the fruit mass, açaí seeds may be ground for livestock food or as a component of organic soil for plants. Planted seeds are used for new palm tree stock, which, under the right growing conditions, requires months to form seedlings. The seeds are a source of polyunsaturated and saturated fatty acids[7][10][11]
A powdered preparation of freeze-dried açaí fruit pulp and skin was reported to contain (per 100 g of dry powder) 533.9 calories, 52.2 g carbohydrates, 8.1 g protein, and 32.5 g total fat. The carbohydrate portion included 44.2 g of dietary fiber and low sugar value (pulp is not sweet).[11] The powder was also shown to contain (per 100 g): negligible vitamin C, 260 mg calcium, 4.4 mg iron, and 1002 U vitamin A, as well as aspartic acid and glutamic acid; the amino acid content was 7.59% of total dry weight (versus 8.1% protein).
The fat content of açaí consists of oleic acid (56.2% of total fats), palmitic acid (24.1%), and linoleic acid (12.5%).[11] Açaí also contains beta-sitosterol (78–91% of total sterols).[11][12] The oil compartments in açaí fruit contain polyphenols such as procyanidin oligomers and vanillic acid, syringic acid, p-hydroxybenzoic acid, protocatechuic acid, and ferulic acid, which were shown to degrade substantially during storage or exposure to heat.[13]
In the general consumer market, açaí is sold as frozen pulp, juice, or an ingredient in various products from beverages (including the grain alcohol, VeeV), smoothies and foods to cosmetics and supplements.
In 2004, it became popular to consume açaí as a supplement due in part to the rapid success of multi-level marketing company MonaVie that sells an açaí blend tonic for $40 a bottle and the proliferation of various açaí supplement companies that misused celebrity names like Oprah Winfrey and Rachael Ray to promote açaí weight loss pills online.[14]
Marketers of these products make unfounded claims that açaí and its antioxidant qualities provide a variety of health benefits, none of which has scientific confirmation to date. False claims include reversal of diabetes and other chronic illnesses, as well as expanding size of the penis and increasing men's sexual virility and sexual attractiveness to women.[15] As of August 2011, there are no scientifically controlled studies supporting any health benefits from consuming açaí. No açaí products have been evaluated (in the United States) by the FDA, and their efficacy is doubtful.[16] Specifically, there is no scientific evidence that açaí consumption affects body weight, promotes weight loss or has any positive health effect.[17]
According to the Washington, D.C. based Center for Science in the Public Interest (CSPI) thousands of consumers have had trouble stopping recurrent charges on their credit cards when they cancel free trials of açai-based products.[18][19] Even some web sites purporting to warn about açai-related scams are themselves perpetrating scams.[17]
In late 2008, lawyers for The Oprah Winfrey Show began investigating statements from supplement manufacturers who alleged that frequent Oprah guest Dr. Mehmet Oz had recommended their product or açai in general for weight loss.[16]
A comparative analysis from in vitro studies reported that açaí has intermediate polyphenol content and antioxidant potency among 11 varieties of frozen juice pulps, scoring lower than acerola, mango, strawberry, and grapes.[20]
A powdered preparation of freeze-dried açaí fruit pulp and skin was shown to contain anthocyanins (3.19 mg/g); however, anthocyanins accounted for only about 10% of the overall antioxidant capacity in vitro.[21] The powdered preparation was also reported to contain twelve flavonoid-like compounds, including homoorientin, orientin, taxifolin, deoxyhexose, isovitexin, scoparin, as well as proanthocyanidins (12.89 mg/g), and low levels of resveratrol (1.1 μg/g).[11] A study on another different freeze-dried açaí product (Opti-Acai) reported that the formulation contained much lower levels of anthocyanins, proanthocyanadins, and other polyphenol compounds as compared with blueberries and other antioxidant-rich fruits.[22]
In an in vitro study of different açaí varieties for their antioxidant capacity, a white one displayed no antioxidant activity against different oxygen radicals, whereas the purple variety most often used commercially had antioxidant activity against peroxyl radicals and to a lesser extent peroxynitrite but little activity against hydroxyl radicals.[21]
Freeze-dried açaí powder was found to have antioxidant activity in vitro against superoxide and peroxyl radicals, and mild activity for peroxynitrite and hydroxyl radicals.[22] The powder was reported to inhibit hydrogen peroxide-induced oxidation in neutrophils, and to have a slight stimulatory effect on the reactive radical, nitric oxide.[23]
Extracts of açaí seeds were reported to have antioxidant capacity in vitro against peroxyl radicals, similar to the antioxidant capacity of the pulp, with higher antioxidant capacity against peroxynitrite and hydroxyl radicals.[24]
The anthocyanins of fruit likely have relevance to antioxidant capacity only in the plant's natural defensive mechanisms[25] and in vitro.[26] The Linus Pauling Institute and European Food Safety Authority state that dietary anthocyanins and other flavonoids have little or no direct antioxidant food value following digestion.[27][28][29] Unlike controlled test tube conditions, the fate of anthocyanins in vivo shows they are poorly conserved (less than 5%), with most of what is absorbed existing as chemically modified metabolites destined for rapid excretion.[30]
When the entire scientific literature to date and putative health claims of açaí are assessed, experts concluded in 2011 that the fruit is more a phenomenon of Internet marketing than of scientific substance.[31][32]
Various studies have been conducted that analyze the antioxidant capacity of açaí juice blends to pure fruit juices or fruit pulp. Açaí juice blends contain an undisclosed percentage of açaí.
When three commercially available juice mixes containing unspecified percentages of açaí juice were compared for in vitro antioxidant capacity against red wine, tea, six types of pure fruit juice, and pomegranate juice, the average antioxidant capacity was ranked lower than that of pomegranate juice, Concord grape juice, blueberry juice, and red wine. The average was roughly equivalent to that of black cherry or cranberry juice, and was higher than that of orange juice, apple juice, and tea.[33]
A study in 12 healthy fasted human volunteers demonstrated that blood antioxidant capacity was increased within two hours after consumption of a commercial açaí juice beverage or applesauce, but did not investigate any physiological effect of these supposed antioxidants.[34] The generation of reactive oxygen species was not significantly affected by açaí juice consumption.
Quackwatch noted that "açaí juice has only middling levels of antioxidants—less than that of Concord grape, blueberry, and black cherry juices, but more than cranberry, orange, and apple juices." The extent to which polyphenols as dietary antioxidants may promote health is unknown as no credible evidence indicates any antioxidant role for polyphenols in vivo,[35][36] In minute concentrations, polyphenols may affect cell-to-cell signaling, receptor sensitivity, inflammatory enzyme activity or gene regulation.[36][37]
Freeze-dried açaí powder was shown to have mild inhibitory effects on cyclooxygenase enzymes COX-1 and COX-2,[22] in vitro. Chemically extracted polyphenolic-rich fractions from açaí were reported to reduce the proliferation of HL-60 (experimental leukemia) cells in vitro.[38] In vitro anti-proliferative effects were also observed with extracts from açaí pulp oil.[39]
In a study of rats fed a high cholesterol diet, supplemental feeding with dry açaí pulp reduced blood levels of total and non-high-density lipoprotein cholesterol and superoxide dismutase activity.[40]
Orally administered açaí has been tested as a contrast agent for magnetic resonance imaging of the gastrointestinal system.[41] Its anthocyanins have also been characterized for stability as a natural food coloring agent.[42]