613

16: Stimulants

Paullinia cupana Kunth

Nov. gen. sp. 5: 91 (1821).

SAPINDACEAE

2n = 14

Paullinia sorbilis Martius (1826).

Guaraná (En, Fr, Brazil).

Paullinia cupana is indigenous to the tropical forests in the central and upper Amazon Basin of South America. It was taken into cultivation as a trimmed shrub, probably around 1850. Commercial production of Paullinia cupana has become important since the 1970s and is largely confined to an area between Manaus and Maués in the Amazonas province of Brazil. It has been cultivated in the Economic Garden of Singapore, where it proved easy to grow.

European travellers of the 18th Century noticed local people in the upper Amazon Basin using seeds of Paullinia cupana to prepare a stimulant beverage for ritual and medicinal purposes. Traditionally, powder scraped from stick-shaped loaves of processed seeds is mixed with water to prepare a strongly invigorating, non-alcoholic beverage with bitter taste and a distinctive flavour mostly appreciated by the local people only. The loaves are sometimes shaped into various animal figures and sold as handicraft art objects. In modern times Paullinia cupana has found industrial application in the preparation of an amber-coloured sweet and carbonated lemonade, or a concentrate that has become very popular in Brazil and to some extent also in Japan and the United States. Guaraná extracts are used to flavour cola drinks, alcoholic beverages and candy.

Almost all commercially grown Paullinia cupana comes from Brazil. Annual production is no more than 1200 t from 4000 ha, with some 70% used by the Brazilian soft drink industry. There is a small export trade, mainly to Japan and the United States. The production is concentrated in the state of Amazonas but Paullinia cupana is increasingly being grown in the states of Bahia and Rondônia too, because at present demand is greater than supply.

The seeds of Paullinia cupana are rich in xanthine alkaloids, caffeine in particular but also theobromine and theophylline. On average, caffeine represents (2.5—)3.5(—6)% of fresh weight. Other constituents include cellulose (47%), proteins (15.6%), tannins (5—11%) and amides (9.4%). Small amounts of saponins, choline and mineral salts are also present. Paullinia cupana derives its stimulating effect from the relatively high caffeine content in the original product, but claims of additional curative properties have not been confirmed in formal medical tests.
The 1000-seed weight is 900—1000 g.

An evergreen, scandent, monoecious shrub, up to 3 m tall when growing in the open, or a woody liana when growing in shade. In cultivation it is pruned to a shrub 2 m tall and 2—4 m in diameter. Stem typically branching into 2 branches near the soil surface, bearing deep longitudinal furrows and axillary tendrils. Leaves alternate, imparipinnate, 5(—11)-foliolate, glabrous; petiole 7—15 cm long; leaflets elliptical to ovate, 10—20 cm x 4.5—9 cm, margin entire or grossly serrate with marginal discoid glands, apex acute to acuminate, shiny green above with lateral veins running undivided from midrib to leaflet margin. Inflorescence an axillary, terminal or tendrillate racemose compound up to 30 cm long, consisting of sessile to elongated, occasionally scorpioid cincinni; pedicel 3—7 mm long; flowers 3—6 cm long, unisexual, male and female flowers on the same inflorescence; calyx unequally 5-lobed; petals 4(—6), oblong, about 5 mm long, white, with scale appendages; extrastaminal disk glands 4; stamens 8; pistil with glabrous ovary, fleshy style and trifid stigma. Fruit a 3-lobed subglobose capsule, 2—3 cm in diameter, yellow to red, containing 1—3 seeds; fruit stalk about 1 cm long. Seed depressed globose, 1.5—2 cm x 1—1.5 cm, dark brown, partly embedded in a white, pulpy aril; embryo about 1 cm long, cotyledons fleshy. Seedling with hypogeal germination.

Paullinia cupana has no seed dormancy and seeds germinate 1—4 months after sowing. Seed viability is quickly lost under dry conditions. The seedling produces a new leaf at monthly intervals, the first 6—10 being unifoliate. First flowering starts 1.5—2 years after seed germination. Inflorescences are borne on new wood developed during the rainy season. Flowering is extended over a period of one month during the early part of the dry season. Mature, multi-stemmed shrubs (4—5 years old) will bear hundreds of inflorescences. Open flowers on inflorescences of one branch are all of the same sex at any one time, pistillate on one particular day and staminate on the next, but each branch on the same plant follows its own pattern of sex synchronization during anthesis. The ratio of pistillate to staminate flowers is about 1 : 5. Pollination is by bees, wasps and possibly also ants. Fruits are mature and dehisce the seeds in about 75 days.

The genus Paullinia L. includes some 200 species, most of them of Amazonian origin. The cultivated Paullinia cupana forms are often referred to as Paullinia cupana var. sorbilis (Mart.) Ducke, which closely resembles the wild type var. cupana. It is better to classify the cultivated forms in a cultivar group, e.g. cv. group Guaraná. The caffeine-rich bark of the related species Paullinia yoco Schultes & Killip is also used by local people of the Amazon basin to prepare a stimulant beverage.

The natural habitat of Paullinia cupana is the humid tropics with average minimum and maximum temperatures of 22°C and 32°C respectively; annual rainfall of at least 2000 mm, but with a period of 2—3 relatively dry months (100 mm) for flowering and fruit ripening. In Amazonia Paullinia cupana is cultivated on the 'terra firme', which are clay oxisols that remain free from flooding.

Seeds of Paullinia cupana are placed in moist sawdust and germinated seeds are planted in black polythene bags filled with topsoil and placed under heavy shade. One-year-old seedlings are planted in the field in the early part of the rainy season (January—February in Amazonia) at a density of 625—1100 plants/ha in a square arrangement of 3—4 m x 3—4 m. Palm leaves are placed over the seedlings as temporary shade to prevent sun scorching.
Vegetative propagation by softwood cuttings is possible, although rate of rooting success varies greatly with different genotypes. Mist propagation and application of indole-3-butyric acid (IBA) improves rooting.

New plantings of Paullinia cupana are usually established on land freshly cleared from forest. Leguminous cover crops (e.g. Pueraria spp.) are sometimes interplanted, but fertilizers are not generally applied in the main areas of cultivation in Amazonia. Maintenance operations include occasional weeding and pruning to control the size of the shrubs.

The commonest and often severe disease in Paullinia cupana is anthracnose from the black speckle fungus (Colletotrichum guaranicola) which causes large lesions on the leaves and inflorescences. Fusarium decemcelallare causes proliferation of buds resulting in masses of unproductive tissue; it can be severe in nurseries. Infected shrubs are uprooted and burned. Other diseases include red root rot (Ganoderma philippii) and black crust (Septoria paulliniae). Various parasitic nematodes attack the roots.

In Amazonia Paullinia cupana fruits from September to January ('dry' season) and ripe fruits are handpicked every other day.

There is a large annual and between-plant variation in yield of Paullinia cupana, ranging from 0.1—9 kg seed per shrub. Growers appear to obtain on average about 500 kg/ha, but 2—4 t/ha have been obtained on experimental stations.

Seeds of Paullinia cupana are washed to remove the white aril and dried to about 10% moisture content. Processing involves roasting the seeds in an oven for 2—3 hours, followed by milling. For local use the powder is mixed with water, kneaded into a paste and made up into round stick-like loaves, 11—18 cm long and 3—4 cm in diameter. These are dried in the sun or by fire and finally they are placed in a smoke house to harden for 40 days. In this form they will keep for years. Traditionally, when required, powder is filed off the loaf with the bony tongue of the pirarucú fish (Arapalma gigas). The soft drink industry uses an extract from the roasted and finely ground seed to prepare a carbonated beverage that also contains artificial flavourings and sweeteners.

Over 700 accessions of Paullinia cupana from throughout the Amazon region have been collected by the Guaraná Research Institute of the 'Empresa Brasileira de Pesquisa Agropecuária' (EMBRAPA), near Manaus, Amazonas, which also has a gene bank with over 200 accessions in Bélem. The Guaraná Research Institute carries out research on cropping methods and on genetic improvement, for which Paullinia yoco may be a promising related species. Several clones are being screened for vigour, yield and resistance to major diseases.

The popularity of Paullinia cupana as a pleasant beverage is increasing. The Brazilian government is encouraging increased production and supporting agronomic research in an effort to capitalize on the expanding demand. Paullinia cupana should have potential as a crop throughout the humid tropics, including South-East Asia.

Beck, H.T., 1990. A survey of the useful species of Paullinia (Sapindaceae). Advances in Economic Botany 8: 41—56.
Corrêa, M.P.F. & dos Santos, V.C., 1983. Guaraná: resumos informativos 11 [Guaraná: informative summaries 11]. 2nd edition. Empresa Brasileira de Pesquisa Agropecuária, Brasília, Brazil. 124 pp.
Empresa Brasileira de Pesquisa Agropecuária, 1984. Anais do 1^o Simpósio brasileiro do guaraná [Annals of the first Brazilian Symposium on guaraná]. EMBRAPA, Unidade de Execução de Pesquisa de Ambito Estadual, Manaus, Brazil. 144 pp.
Erickson, H.T., Corrêa, M.P.F. & Escobar, J.R., 1984. Guaraná (Paullinia cupana) as a commercial crop in Brazilian Amazonia. Economic Botany 38(3): 273—286.
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Freire, F.C.O., Albuquerque, F.C. & Duarte, M.L.R., 1978. The black speckle of fruits of guaraná, Paullinia cupana var. sorbilis. Centro de Pesquiso Agropecuária do Tropico Umido, Empresa Brasileira de Pesquisa Agropecuária, Belém, Brazil. Fitopatologia Brasileira 3(3): 271—276.
Henman, A.R., 1982. Guaraná (Paullinia cupana var. sorbilis): ecological and social perspectives on an economic plant of the central Amazon basin. Journal of Ethnopharmacology 6(3): 311—338.
Lleras, E., 1994. Species of Paullinia with economic potential. In: Hernández Bermejo, J.E. & León, J. (Editors): Neglected crops: 1492 from a different perspective. FAO Plant Production and Protection Series No 26. Food and Agriculture Organization of the United Nations, Rome, Italy. pp. 223—228.

G.T. Prance

Prance, G.T., 2000. Paullinia cupana Kunth. In: van der Vossen, H.A.M. and Wessel, M. (Editors): Plant Resources of South-East Asia No 16: Stimulants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea