There are literally hundreds of species of palm trees that oftentimes dominate the vegetation of regularly flooded rainforest lands in the Amazon. Up to seven thousand palm trees per acre have been recorded in some areas of the rainforest. The Palm family, with over 1200 species split into 32 generic groups, is one of the most useful families of plants and widely used by rainforest inhabitants. Palm trees have long provided a range of products including food, beverages, cooking oil, clothing, construction materials, tools, weapons and household wares.
Acai is a very common, tall, slender palm tree in this important palm family which grows 15 to 25 m in height. The average mature wild tree has 4-8 well-developed stems (10-15 cm in diameter) from a single seed and root system; however, a single seed can grow a plant providing up to 25 shoots growing individually. It has pinnate leaves that start from a prominent crownshaft that is reddish color. It has adapted to live in periodically waterlogged and flooded soils by developing special root structures called pneumatophores. It produces both female and male flowers which are quite small and are brown to purple in color.
Acai also produces an edible fruit which grows in bunches. The fruit is round, 1-2 cm in diameter, with a single large seed inside surrounded by stringy fibrous sheaths and a thin oily coating. It begins as a green color and ripens to a dark purple. Each tree stem usually produces four to eight bunches of fruit throughout the year but ripe fruits are the heaviest in the dry season (July to December) Each bunch can weigh up to 6 kg and one stem/trunk normally yields, on average, 24 kgs of fruit annually. In its natural habitat under the shady rainforest canopy, the acai tree grows slowly in low light, often taking 4-5 years before producing fruit. The fruit is favored by birds and rodents and the seeds are disbursed through the forest in their droppings. Found throughout the Amazon and especially prevalent in the Brazilian state of Pará, acai is extremely common throughout the lowland flood areas along the rivers of northern South America where it forms large groves.
Acai and other Euterpe palm trees are the subject of commercial exploitation in South America. Palm hearts, eaten worldwide as a vegetable, are obtained by cutting the palm and removing the crownshaft, in which the heart is found. Palm hearts are the tender, whitish immature leaves of the palm frond just above the growing point on each stem. Although is has almost no nutritious value, palm hearts have been a staple food enjoyed by the local populations for generations and have also become a economic resource and export product for many rainforest countries. France, followed by the U.S. are the largest importers of palm hearts. There are over 120 registered palm heart processors operating in the Amazon, with a multitude of smaller unregistered family operations selling their harvests to the larger facilities with onsite canning operations. Originally, much of the commercial palm heart production in South America beginning in the 1960's came from a different palm tree, Euterpe edulis, which only produces a single trunk. (However, one large tree can yield up to 50 pounds of palm hearts.) Because the tree must be felled to extract the palm heart, palm heart exploitation without any adequate management severely decimated the wild populations of this species at an alarming rate.
After many native E. edulis palm groves disappeared, harvesters began using the acai palm as a more sustainable alternative since it produces many stems/trunks. Unlike it's cousin, when one of acai's stems is cut, more stems will grow back on the same root system and the cutting of some of the stems encourages fruiting on the remaining stems. Acai palm (E. oleracea) is now the world's main source of palm hearts. While Acai does offer a more sustainable alternative, it does not ensure that the correct exploitative harvesting methods will be used to guarantee the plant's survival. Huge stands of acai palm are often over-exploited and sometimes entire groves are clear-felled for palm heart exploitation. Currently, there is a shortage of raw materials in many locations in the Amazon River estuary due to over-harvesting and a lack of sustainable management of native stands; palm heart processing plants in the area generally operate only 2-3 days per week.
Many botanists disagree that palm heart harvesting of any species is sustainable at all since ninety-five percent of the tree is wasted in the process. What may well guarantee it's survival is the new, rapidly growing, and profitable export market for the acai fruit, which might surpass the profits gleaned from harvesting the palm heart in the near future.
TRIBAL AND HERBAL MEDICINE USES
In the Amazon, the acai palm heart is widely consumed as a vegetable, the fruit is prepared into a popular fruit drink and used as a natural ink or dye, and the wood is used in house construction (palm thatched roofs). Ethnobotanists have recorded no less than 22 different uses for all parts of the tree. In the Brazilian Amazon, the Indian tribes of the forest use all parts of the tree. They fell the tree and eat the palm heart, turn the fruit into a juice drink, and use the mature palm fronds for thatch for their house roofs. They then urinate on the rest of the felled tree to attract a species Rhynchophorus palm beetle to lay it's eggs inside the felled tree. Several weeks later, they return to harvest 3-4 pounds of beetle grub larvae which are an important source of protein (62%) and fat (4.5%) in their diet. The fruit juice is also very popular throughout the local communities and indigenous tribes of the Amazon; resulting in acai trees commonly planted in gardens, around villages, and in back yards. The fruit and palm hearts are also taken into river cities and towns where they are sold as cash crops by river- and forest-dwelling families.
In Brazilian herbal medicine, the oil of the fruit is used to treat diarrhea; an infusion of the root is used for jaundice and to build the blood; an infusion of the grated fruit rind is used as a topical wash for skin ulcers; and, the fruit seeds are crushed and prepared in an infusion for fevers. In the Peruvian Amazon, an infusion of the toasted crushed seeds is used for fever, and a decoction of the root is used for malaria, diabetes, hepatitis and jaundice, hair loss, hemorrhages, liver and kidney diseases, menstrual pain, and muscle pain. In Colombia, where the trees grow along the Pacific coast line, it is called naidí and the fruit is turned into a common and popular drink.
By far, the main use of acai by the local inhabitants of the Amazon is for the preparation of a thick, dark purple juice obtained by macerating the ripe fruits. In some areas, individual consumption of up to 2 liters daily has been recorded. It is often referred to as "poor-man's juice." It is so popular, there is usually a small special establishment called an acailandia in most Amazon river towns and villages that prepare the acai juice and sell it in small plastic bags. Although a basic part of the diet of the poor, acai liquid has become popular throughout all socioeconomic levels. It has a metallic nutty flavor with a creamy texture and oily appearance. To prepare the liquid the ripe fruits are soaked in water to soften the thin outer shell. The fruits are then squeezed and the large seeds strained out to produce a dense purple liquid with a distinctive flavor. In the Amazon, the liquid is often combined with a starchy root vegetable called manioc (which has been dried and ground into a flour) and is eaten as a purple porridge. It is mixed with sugar or sugar cane to sweeten and drunk as a beverage, as well as used to flavor ice cream, liquor and other desserts.
Acai is a staple food for many economically disadvantaged inhabitants of the lower Amazon region area. The acai-manioc porridge is quite poor in nutrition but is very filling with a large amount of starch and sugar. In Belém, a major port and gateway into the Brazilian Amazon, an enormous acai fruit market called Feira do Acai houses 70 to 120 vendors selling over 200,000 kg of acai fruit daily during the dry season. The fruit juice is widely consumed as a staple, however, no medicinal properties have been associated with it. Prepared acai fruit drinks sell for about $2 per liter on the streets of Belém, making it highly affordable for everyone.
The fruit liquid, called simply acai or vinho de acai (although it's not alcoholic or fermented) is not really that nutritious in comparison to many other fruit juices. The nutrient content analyzed is 1-4% protein, 7-11% fats, 25% sugar, 0.05% calcium, 0.033% phosphorous, and 0.0009% iron. It also has some sulphur, traces of vitamin B1 and some vitamin A and E. It also delivers 88 to 265 calories per 100 grams, depending on the preparation method.
The dark purple color of the fruit is due to the polyphenolic compounds present. One of the main plant chemicals getting a lot of attention in acai, is a compound called anthocyanin. Anthocyanins are a group of flavonoids widely distributed in plants and lending a red to purple color to fruits like grapes, blackberries, and raspberries. As a well known antioxidant, anthocyanin-rich foods and fruits have been marketed as cancer preventative and anti-aging products. Anthocyanins have also been studied as novel sources of natural food colorings and dyes. The anthocyanin in acai however is highly unstable and degrades easily in the presence of heat, humidity, as well as in the presence of enzyme actions of other chemicals in the fruit. This makes acai fruit highly perishable; it readily changes in color, taste, and anthocyanin content with even short term (12 hours) refrigerated storage.
In addition to the standard vitamins and minerals found in most fruits, the main plant chemicals in acai fruit include epicatechin, p-hydroxy-benzoic acid, gallic acid, (+)-catechin, protocatechuic acid, ellagic acid, p-coumaric acid, ferulic acid, vanillic acid, cyanidin, and pelaronidin 3-glucoside.
BIOLOGICAL ACTIVITIES AND CLINICAL RESEARCH
Acai has not been the subject any studies to determine biological activity since it isn't traditionally used for any type of medical condition. Most of the published research over the last few years have concerned pasteurization and extraction methods being developed in an effort to provide for longer storage of a highly perishable fruit. One single in vitro test was reported in which they extracted the well known antioxidant, phenols and anthocyanin chemicals from the fruit and demonstrated these chemicals had the ability to retard cancer cell growth in a test tube. As all the chemicals extracted from acai for this study were well known chemicals (no novel chemicals found yet in acai) found in other common fruits and plants and which had similar in vitro cancer cell studies performed, this was not anything profound or new.
CURRENT PRACTICAL USES
In the Brazilian Amazon more research and development is being done in the states of Pará and Amapá where various non-governmental organizations and university-based projects are promoting the sustained yield management of secondary flooded forests with a predominance of acai palms. With a continuing profitable market for the fruit and palm heart, it remains to be seen if natural rainforest lands are clear-cut for the profits to be had in the mass plantation-type cultivation of acai. One proposed project in Brazil calls for the planting of 5 billion acai trees in the next 10 years. Therefore, it also remains to be seen whether acai demand can strike a balance between rainforest conservation and the development of economic opportunities.
Much of the new acai fruit demand has resulted from several new product launches in the U.S. It seems the U.S. is in an "acai craze" today as a result of a some high dollar marketing programs touting it as the new, mysterious, power fruit of the Amazon... along with a host of health benefits - from weight loss, to increased energy and lower cholesterol. This type of marketing strategy isn't new however. It is a direct result of other "exotic" fruit products like noni and mangosteen netting billions in U.S. sales through network marketing companies and direct retail sales playing on the exotic flair of some common tropical fruit but that isn't well known in the U.S. Since noni's profitable appearance in the U.S. market several years ago, many enterprising companies have been searching for the next and newest (highly profitable) noni-replacement from an "exotic" tropical fruit.
Ironically, Brazil's "poor man's juice" seems to have temporarily filled the bill as the new high-dollar "rich man's" health drink in the U.S. Brazilian heads are shaking at this recent American acai craze (as well as the high prices!) but they are certainly trying to increase production of acai fruit so they can capitalize off it as well. Various acai products are now widely available (and heavily marketed) in the U.S. natural products market - from liquid fruit drinks and freeze-dried or powdered juice extracts in capsules and tablets, to ingredients in natural energy bars and snacks. As with any product with a high-dollar marketing campaign behind it promising all the usual "loose weight, stay young, prevent disease and have more energy" impluse desires of most Americans... consumers still need to question the claims, do their own research, and try to choose a product with a money-back guarantee in the likely event that the product doesn't live up to it's far-reaching claims.
Acai is an interesting fruit and highly popular as a low-cost beverage where it grows, but it has never been marketed or sold in Brazil or in the Amazon for any health benefits whatsoever. (And remember, in one Amazon city alone, over 400,000 pounds of acai fruit is sold daily!) It makes one wonder... could an enterprising American launch an "exotic" cranberry juice drink to Amazonians who'd never heard of or seen a cranberry and get them to pay $40 a quart for it? Who knows... at least cranberries have some medicinal uses for urinary tract health!