The acai palm or aqai (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 European adaptation of the Tupian word ''iwasa'i'', '[fruit that] cries or expels water'. Global demand for the fruit has expanded rapidly in recent years, and acai is now cultivated for that purpose primarily. The closely-related species Euterpe edulis (jucara) 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. Acai palms are tall, slender palms growing to 15–30 meters, with pinnate leaves up to 3 meters long.
Harvesting and uses
The fruit, a small, round, black-purple drupe about 1-inch in circumference, similar in appearance but smaller than a grape but with less pulp, is produced in branched panicles of 500 to 900 fruits. Two crops of fruit are produced each year. The fruit has a single large seed about 0.25–0.40 inches in diameter. The exocarp of the ripe fruits is a deep purple color, or green, depending on the kind of acai 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 seed with a diminutive embryo and abundant endosperm. The seed makes up about 80% of the fruit .
The berries are harvested as food. In a study of three traditional Caboclo populations in the Brazilian Amazon, acai 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.
In the northern state of Para, Brazil, acai pulp is traditionally served in gourds called "cuias" with tapioca and, depending on the local preference, can be consumed either salty or sweet . Acai has become popular in southern Brazil where it is consumed cold as acai na tigela ("acai in the bowl"), mostly mixed with granola. Acai is also widely consumed in Brazil as an ice cream flavor or juice. The juice has also been used in a flavored liqueur. Since the 1990s acai juice and extracts are used globally in various juice blends, smoothies, sodas, and other beverages.
In May 2009, Bloomberg reported that the expanding popularity of acai in the United States was "depriving Brazilian jungle dwellers of a protein-rich nutrient theyve relied on for generations."
As a dietary supplement
Recently, the acai berry has been marketed as a dietary supplement. Companies sell acai berry products in the form of tablets, juice, smoothies, instant drink powders, and whole fruit.
Marketers of these products make claims that acai provides increased energy levels, improved sexual performance, improved digestion, detoxification, high fiber content, improved skin appearance, improved heart health, improved sleep, and reduction of cholesterol levels. Quackwatch noted that "acai juice has only middling levels of antioxidantsless than that of Concord grape, blueberry, and black cherry juices, but more than cranberry, orange, and apple juices."
Furthermore, the extent to which polyphenols as dietary antioxidants may promote health is doubtful. No credible evidence indicates any antioxidant role for polyphenols in vivo, but rather in minute concentrations, they may affect cell-to-cell signaling, receptor sensitivity, inflammatory enzyme activity or gene regulation. Specifically, there is no scientific evidence that acai consumption affects body weight or could promote weight loss.
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 acai-based products. Even some web sites purporting to warn about acai-related scams are themselves perpetrating scams. Apparently 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.
As of March 2009, there are no scientifically controlled studies backing up any of these claims. According to ABC News correspondent Susan Donaldson, these products have not been evaluated (in the United States) by the FDA, and their efficacy is questionable. In late 2008, lawyers for The Oprah Winfrey Show began investigating alleged statements from supplement manufacturers who suggested that frequent Oprah guest Dr. Mehmet Oz had recommended their product or acai in general for weight loss.
Apart from the use of its berries as food or a flavoring in tequila, the acai 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. Tree trunks may be processed to yield minerals.
Comprising 80% of the fruit mass, acai 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
A powdered preparation of freeze-dried acai 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. 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.
The fat content of acai consists of oleic acid (56.2% of total fats), palmitic acid (24.1%), and linoleic acid (12.5%). Acai also contains beta-sitosterol . The oil compartments in acai 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.
Polyphenols of acai raw materials
A comparative analysis from in vitro studies reported that acai has intermediate polyphenol content and antioxidant potency among 11 varieties of frozen juice pulps, scoring lower than acerola, mango, strawberry, and grapes.
A powdered preparation of freeze-dried acai fruit pulp and skin was shown to contain anthocyanins ; however, anthocyanins accounted for only about 10% of the overall antioxidant capacity in vitro. The powdered preparation was also reported to contain twelve flavonoid-like compounds, including homoorientin, orientin, taxifolin, deoxyhexose, isovitexin, scoparin, as well as proanthocyanidins , and low levels of resveratrol (1.1 mg/g). A study on another different freeze-dried acai 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.
In an in vitro study of different acai 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.
Freeze-dried acai powder was found to have antioxidant activity in vitro against superoxide (1614 units/g) and peroxyl radicals (1027 mmol TE/g) and mild activity for peroxynitrite and hydroxyl radicals. The powder was reported to inhibit hydrogen peroxide-induced oxidation in neutrophils, and to have a slight stimulatory effect on nitric oxide production by lipopolysaccharide-stimulated macrophages in vitro. These results, however, apply only to in vitro conditions and remain unknown for whether they are physiologically relevant. Rather, more subtle, non-antioxidant roles in vivo are likely.
Extracts of acai 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.
Antioxidant potential of acai juice
When three commercially available juice mixes containing unspecified percentages of acai 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.
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A study in 12 healthy fasted human volunteers demonstrated that blood antioxidant capacity was increased within two hours after consumption of a commercial acai juice beverage or applesauce, but did not investigate any physiological effect of these supposed antioxidants. The generation of reactive oxygen species was not significantly affected by acai juice consumption.
Although acai is notable for its potentially rich polyphenol content, the anthocyanins of this fruit likely have relevance to antioxidant capacity only in the plant's natural defensive mechanisms and in vitro. This reasoning applies because phenolic antioxidant properties of acai are unlikely to be conserved after the fruit is consumed, as interpreted by the Linus Pauling Institute which states that dietary anthocyanins and other flavonoids have little or no direct antioxidant food value following digestion. Not like 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." Studies force new view on biology of flavonoids", by David Stauth, EurekAlert!. Adapted from a news release issued by Oregon State University
The increase in antioxidant capacity of blood seen after consumption of anthocyanin-rich foods like acai is not caused directly by the anthocyanins or other polyphenols, but most likely results from increased uric acid levels derived from polyphenol metabolism. According to Frei, "we can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them."
Freeze-dried acai powder was shown to have mild inhibitory effects on cyclooxygenase enzymes COX-1 and COX-2, and chemically-extracted polyphenolic-rich fractions from acai were reported to reduce the proliferation of HL-60 (experimental leukemia) cells in vitro. In vitro anti-proliferative effects were also observed with extracts from acai pulp oil. In a study of rats fed a high cholesterol diet, supplemental feeding with dry acai pulp reduced blood levels of total and non-high-density lipoprotein cholesterol and superoxide dismutase activity.
Orally-administered acai has been tested as a contrast agent for magnetic resonance imaging of the gastrointestinal system. Its anthocyanins have also been characterized for stability as a natural food coloring agent.
Environment of Brazil
List of plants of Amazon Rainforest vegetation of Brazil
Pictures of acai palms trees and fruit from an article by The Nature Conservancy.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Acai Palm