The author of this chapter is E. Lleras (CENARGEN/EMBRAPA, Brasilia, Brazil).
Botanical name: Paullinia cupana H.B.K.
Common name: guarana
Guarana is undoubtedly among the stimulants that are attracting most attention from the developed countries nowadays. All kinds of qualities are being attributed to it, from that of being a simple stimulant to an aphrodisiac, and it is now a must in the herbalist's shop. It was already cultivated at the time of the discovery and, from the seventeenth century, its seed occupied a prominent place among the products used for local consumption and export in the region of Manaus in Amazonia. According to one missionary, certain Indian tribes valued it in the same way as "the whites valued their gold". The use of guarana in Europe was documented in 1775, but information on its production up to the beginning of this century is very uncertain. The only information available for last century relates to the export of 262 arrobas (1 arroba = 11.5 kg) to Europe in 1852.
In 1923, the harvest was 3 873 kg. After a harvest of 124 000 kg in 1935, since no exports took place and domestic consumption had gone down, there was a surplus of guarana which led the government of the state of Amazonas and the producers to form the Emporio de Guarana, which was granted the marketing monopoly of the product. As from 1966, with the winding up of the Emporio, which served more as a stagnating than development factor, an industrial system for the product began to be established. The aggressive internal and external publicizing policy for guarana, adopted by the government and begun at the end of the 1940s, led to the present situation where demand is several times greater than supply.
Both official records and socio-economic studies indicate that there were two main production phases: the extraction or collecting phase, which extended up to the 1970s, and the cultivation phase from that time on.
Guarana is used mainly to produce a soft drink. For a long time, it was used empirically in medicine; it is attributed antipyretic, antineuralgic and antidiarrhoeal properties and is reputed to be a powerful stimulant, an analgesic comparable to aspirin and an anti-influenza agent. The seeds contain 2.7 to 3.5 percent caffeine as well as theophylline and theobromine. The traditional method of using guarana (the only one until the 1950s and one that is still widespread nowadays) is as follows: when the fruit has been harvested, the seeds are separated and stored until fermentation of the aril, which is then removed. They are then roasted and their seed coat is removed; this is marketed as "guarana en rama", i.e. raw guarana. The remaining seeds are immersed in water to form a paste. From this are made sticks which, after being dried over a slow fire and smoked for one month, are marketed. The traditional way of preparing the drink consists of grating part of the stick in water to produce an infusion. The guarana carbonated drinks industry began in 1907 and the product became Brazil's national drink during the 1940s. In 1973, the Law on Juices laid down regulations for the use of guarana, defining the maximum and minimum concentrations for carbonated drinks, syrups and other products. In 1981, EMBRAPA's Agricultural Research Centre of the Semi-Humid Tropics (CPATU) developed soluble guarana. Nowadays, guarana is marketed as sticks and soluble or insoluble powder and is used industrially for the production of carbonated drinks, syrups and herbalists' products.
Guarana is a scandent shrub or woody liana. Its leaves are alternate with five folioles and, when tendrils exist, they are axillary. The inflorescences are on axillar racemes or originate on the tendrils. The flowers are male and female, zygomorphous and have five petals and sepals, eight stamens and a trilocular ovary with a glandular semi-disc at the base. The fruit occurs in a septicidal capsule. it is orangey-red and partially open when ripe, revealing one to three black or greenish seeds which are covered at the base with a white aril. The var. cupana differs from the var. sorbilis in that it has no tendrils, its folioles are more strongly lobed and its flowers and fruit are bigger.
Guarana is a monoecious, allogamous species. It is fertilized by bees of the genera Melipona and Apis. It is probably dispersed naturally by birds, although the distances to which it can be disseminated are not known. Its seeds are recalcitrant and lose their viability in 72 hours under normal conditions. Germination can take more than 100 days.
Figure 25. A) Guarana (Paullinia cupana); A1) inflorescences on the raceme; A2) fruit in the capsule; A3) trilocular ovary
The genus Paullinia is predominantly neotropical, extending from Mexico and the southern United States to Argentina. A single species, P. pinnata, is found in both America and Africa.
The soils in which it is found in the native state are generally gley soils or dystrophic lateritic soils. The climate of the region of origin is Am in Köppen's classification, with an annual precipitation of approximately 2200 to 2500 mm. The temperature is isothermal, with an annual mean of 28 to 29°C.
The var. cupuna, on the basis of which the species was described from material collected by Humboldt in San Fernando de Atabapo, Venezuela, is known only in the area between the south of the Atures and Maipures torrents of the Orinoco River and in the region of the upper Negro River and tributaries on the frontiers between Brazil, Colombia and Venezuela, where it seems to be relatively common. It is used by the natives of the Mapiripán region on the Guaviare River in Colombia. The var. sorbilis, or true guarana, seems to have been domesticated in the southern strip of the Amazon River between the gorges of the Purús and Madeira Rivers. From the middle of the last century, it was cultivated in what are now the municipalities of Borba, Maués, Parintins, Manaus and Itacoatiara, and these continue to be the most important centres for the cultivation and distribution of material for other localities. The geographical disjunction between the two varieties has been attributed to anthropic factors; according to this hypothesis, the species was domesticated in the Maués region from a woody liana which reaches the forest canopy. Both the plant and the way of eating it were introduced to the upper Negro River area by the Barrés (or Barés), who gradually migrated north. Domestication of the species must have been very old to enable the formation of a new variety. According to this hypothesis, the var. cupana is a subspontaneous form derived from domesticated guarana. Regarding the existence of guarana in the native state, some information available suggests that, even today, the Maués Indians are introducing wild material into their crops in spite of the fact that it has been stated that guarana is known only in cultivation. Its presence outside the areas mentioned is poorly documented. A specimen collected at the Curuquetê River, on the border between the states of Amazonas and Acre (Brazil), seems to be P. cupana, and there are also reports that it grows spontaneously around Santarém in Pará. The same thing is happening in the case of guarana as has happened with other cultivated species: botanists are ignoring them because they are not taxonomically new.
Paullinia yoco, the other species used as a stimulant, is only known in the wild state and is distributed in a relatively small region along the Putumayo River on the frontier between Colombia and Peru.
There are two varieties of Paullinia cupana. There is no information on the genetic variability of the var. cupana, which is little known and little studied.
P. cupana var. sorbilis shows a high degree of variability. It grows mainly in the planted fields of small producers in the municipalities of Maués, Parintins and Borba in the state of Amazonas. EMBRAPA has a valuable collection located in the experimental field of Maués and a gene bank with more than 200 accessions in Belém (CPATU). There is also a working collection at the CPAA/EMBRAPA in Manaus, with over 700 accessions. There appears to be no risk of genetic erosion, since both the agricultural research system and the producers are aware of he value of the material in their possession. The closest wild species belong to the Pleurotoechus section of the genus. There are nine species of it in Brazilian Amazonia, all with certain morphological resemblances to P. cupana. The closest taxon is P. cuneata, which may belong to the same species (P. cupana). This, together with P. yoco, merits special attention for possible improvement programmes. The areas of greatest interest for prospecting are the basin of the Putumayo River (P. yoco) and the frontier area between Brazil, Peru and Bolivia (the Madre de Dios river basin), where P. cuneata and a species which may be a wild form of P. cupana are found. Also of great importance is the upper Negro River, including considerable portions of the Amazonia and Orinoco regions of Colombia and Venezuela. Nowadays, the var. cupana is considered to be of possible fundamental importance for the improvement of guarana.
Traditional cultivation of guarana is carried out with full exposure to sun on soils with a low fertility (exchange capacity of 20 to 40 ppm), a low acidity (pH between 3.5 and 4.5) and with high concentrations of aluminium. Fertilizers are not used. Spacing of the plants is approximately 4 x 5 m, which gives 500 plants per hectare. After the second year, pruning is carried out to remove old and diseased branches and those which flowered the previous year. Since 1980, a new type of management has been adopted, using the same layout but with fertilizers and pruning to direct the branches along supports. According to technical recommendations, guarana must be grown in areas with a climate similar to its region of origin, with a mean annual temperature between 22 and 20°C. The minimum temperature tolerated is 12°C. Annual precipitation must exceed 1400 mm, with rain well distributed during the year. Soils must be deep, medium or heavy in texture, well drained and with a high organic matter content. Traditional planting is by sowing: the oldest plantations are very heterogeneous both from the genetic and the phenotypical points of view. Prominent among the more modern techniques is propagation from cuttings, for which misting chambers, grafts and tissue culture propagation need to be used.
The average production of the harvesting phase (1938 to 1970) was 175 tonnes per year, with many fluctuations. In the last five years for which cultivation data are available (1983 to 1987), the average was a little over 1 200 tonnes per year, with about a sevenfold increase over the former statistics. Although an extension of the cultivated area influenced this increase, the rise in productivity per hectare also made a substantial contribution, its average almost doubling between the first five years of the 1970s and the last five years recorded, with averages of 71.5 and 137.8 kg of seed per hectare, respectively. This increase in production can easily be attributed to the new type of management, since in field experiments production data were obtained for the traditional system (79 kg per hectare) and improved system (130 kg per hectare) which were very similar to the averages referred to.
As may be seen, Brazil's production is increasing considerably. Until the mid-1970s, the state of Amazonas was the only producer; in the last ten years, other states have begun to produce guarana, notably Bahia and Mato Grosso. In 1987, Bahia's production exceeded that of the state of Amazonas for the first time.
Outside Brazil, other countries are beginning to produce guarana. However, there is little information available. In the great majority of cases, cultivation is beginning with a very limited genetic base, since Brazil does not authorize the export of seeds or vegetative material.
Undoubtedly the biggest limitation today is low productivity, since an average yield per individual ranges between 250 g (traditional cultivation) and 520 g (improved management) of dry kernel and therefore still leaves much to be desired. In part, this problem is strictly agronomic and will be resolved once plantings are carried out under more favourable conditions.
The selection of more productive early material that is resistant to disease and stress-a process begun in Manaus as early as 1980-will be bound to lead to an increase in productivity, since individuals have been identified in experimental and commercial plantings with yields of between 4 and 6 kg of dry seed per hectare per year. The production of hybrids, either through traditional methods or using genetic engineering techniques, will also be of great importance, especially in conjunction with the production of clonal material which allows more uniform treatment and management to be achieved. The genetic basis for these improvement programmes already exists, not only within the available genetic stock of guarana but also of cupana, and possibly in other species of Paullinia such as P. yoco and P. cuneata. The potential market for 1983 was estimated to be around 16000 tonnes and has increased since that year. The shortfall of guarana is around 10 to 15 times the current production volume, which still allows a considerable expansion of cultivation.