Vanilla planifolia (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1, flowering branch; 2, fruit

Vanilla planifolia H.C. Andrews

Protologue: Bot. repos. 8: pl. 538 (1808).

Family: Orchidaceae

Chromosome number: 2n = 25, 26, 28, 30, 31, 32

Synonyms

• Vanilla mexicana P. Miller (1768) p.p.,
• V. viridiflora Blume (1825),
• V. fragrans (Salisb.) Ames (1924).

Vernacular names

• Vanilla (En)

• Vanille (Fr)

• Indonesia: panili

• Philippines: vanilla

• Thailand: wanila

Origin and geographic distribution

Vanilla is indigenous to south-eastern Mexico, Guatemala, and other parts of Central America and the Antilles. In Central America the fruits were used by the Aztecs to flavour cocoa. The fruits became known in Europe in the 16th Century but not until the second half of the 19th Century did large-scale cultivation start outside the natural distribution area. Nowadays vanilla is cultivated pantropically but the important production areas are Indonesia, Madagascar, Comores, Tonga, Réunion, Mexico and French Oceania. In Indonesia vanilla is mainly cultivated in Java and Bali.

Uses

The interesting part of vanilla is the fruit (also called "bean”). The fruits or their extract are used as a spice, e.g. in the flavouring of chocolate, biscuits, confectionery and ice-cream. In the United States the regulatory status "generally recognized as safe” has been accorded to vanilla beans (GRAS 3104), vanilla extract (GRAS 3105) and vanilla oleoresin (GRAS 3106). The maximum permitted level of vanilla extract in food is 1%. Vanilla is the second most expensive spice (after saffron), so it is not surprising that the synthetic substitute vanillin has taken the place of vanilla in the perfume industry and is also widely used in the food industry. Poorer quality vanilla is used to aromatize tobacco in Java. In the United States and Western Europe vanilla is one of the major flavourings in ice-cream and high-quality confectionery and foodstuffs.

In major consuming countries (United States, European Union) vanilla is the only spice which benefits from a "Standard of Identity” which helps shield vanilla beans from competition from substitutes.

In traditional medicine vanilla fruits are used as an aphrodisiac, carminative, emmenagogue and stimulant; they are said to reduce or cure fevers, spasms and caries. Vanilla extracts (especially tinctures according to pharmacopoeias) are used in pharmaceutical preparations such as syrups, primarily as a flavouring agent.

Production and international trade

Most vanilla is grown by smallholders. During the period 1991-1995, annual world production averaged 4843 t (from 41 566 ha), rising to nearly 5000 t in 1997. In South-East Asia the only country with data on vanilla production is Indonesia, with an annual production of 1792 t and a harvested area of 14 500 ha (1991-1995), reaching 2000 t in 1997.

World exports from producing countries ranged from 1560-1850 t annually during the period 1991-1995. The major producing and exporting countries and their exported amounts and average world market share were: Indonesia (682 t, 40%), Madagascar (673 t, 40%), Comores (2110 t, 12%), Tonga (38 t, 2%). Other South-East Asian countries which export or re-export small quantities of vanilla are Malaysia, the Philippines, Thailand and Singapore.

The United States is the leading importer of natural vanilla, with an average of 1326 t per year during the period 1991-1995 (49% of world imports), followed by Germany (326 t), France (295 t) and Canada (160 t).

The price of Bourbon vanilla (produced in the Indian Ocean Islands) on the United States market averaged US$ 70,000 per t during the years 1988-1992. In the same period Indonesian vanilla fetched a price of US$ 26,000 per t.

Properties

Freshly harvested green fruits contain about 80% water which is reduced to about 20% by curing and drying. Per 100 g edible portion cured fruits contain approximately: water 20 g, protein 3-5 g, fat 11 g, sugar 7-9 g, fibre 15-20 g, ash 5-10 g, vanillin 1.5-3 g, a soft resin 2 g and an odourless vanillic acid.

The vanillin content of cured Indonesian vanilla is high (2.75%) in comparison with cured vanilla from other sources: Mexico 1.75%, Sri Lanka 1.5%, Tahiti 1.7%. Vanilla fruits from Tahiti contain heliotropin which gives them their distinctive flavour. Calcium oxalate crystals are present in the plant, which may cause dermatitis in vanilla workers.

A monograph on the physiological properties of vanilla extract (tincture) has been published by the Research Institute for Fragrance Materials (RIFM).

Composition

Vanilla extract (Source: Klimes & Lamparsky, 1976.)

• 85.0% vanillin
• 8.5% 4-hydroxybenzaldehyde
• 1.0% 4-hydroxybenzyl methyl ether
• 0.5% acids and esters
• 0.5% acetic acid
• 0.5% phenols (alkyl) (unknown structures)
• 0.5% esters (unknown structure)
• 0.5% alkanes & alkenes
• 0.5% alkylbenzenes
• 0.1% sesquiterpene hydrocarbons
• 97.6% total

Adulterations and substitutes

Vanilla is the spice most subject to competition from artificial flavourings. Four types of these substitutes exist to date: synthetic vanillin, ethyl vanillin, other natural flavours and tissue culture products. Synthetic vanillin (prepared e.g. from lignin and eugenol) accounts for more than 90% of the United States vanilla flavouring market and is only 1% of the price of the natural product. Natural vanillin is superior, probably due to the presence of subsidiary substances.

For substitute Vanilla species, see Other botanical information.

Description

• A fleshy, herbaceous, perennial vine, climbing up trees to a height of 10-15 m by means of long, whitish, adventitious roots, opposite the leaves. Stem long, cylindrical, 1-2 cm in diameter, simple or branched, succulent, dark green.
• Leaves alternate, fleshy, subsessile; blade oblong-elliptical to lanceolate, 8-25 cm × 2-8 cm, somewhat rounded at base, acute to acuminate at top, with numerous parallel veins.
• Inflorescence a short axillary raceme, 5-10 cm long, 6-15(-30)-flowered, with usually only 1-3 flowers open at one time, starting from the base.
• Pedicel very short; flower about 10 cm in diameter, waxy, fragrant, yellow-green; sepals 3, oblong, 4-7 cm × 1-1.5 cm; 2 upper petals resembling the sepals but slightly smaller, labellum (lower petal) trumpet-shaped, 4-5 cm × 1.5-3 cm, obscurely 3-lobed at top, inside hairy at base; column 3-5 cm long, attached to labellum, bearing at its tip 2 pollinia covered by a cap; stigma concave, separated from the pollinia by a thin flap-like rostellum.
• Fruit a pendulous, narrowly cylindrical capsule, 10-25 cm × 0.8-1.5 cm, obscurely 3-angled, splitting longitudinally when ripe.
• Seeds numerous, globose, about 0.4 mm in diameter, black.

Growth and development

Commercial vanilla is always propagated by stem cuttings. Shoots develop on the cutting 30-40 days after planting. Under favourable conditions a vine may grow 0.6-1.2 m per month.

When cultivated, vanilla flowers on shoots that hang down from the branches of a support tree. Under natural circumstances flowering occurs on upward climbing vines at a height of 10-15 m. This may indicate that a certain amount of vegetative growth is necessary for flowering. Vanilla usually starts flowering 3-4 years after planting and reaches maximum production 7-8 years after planting. About 10 years after planting the commercial value of the vines decreases, so plants are discarded.

A dry period initiates flowering. Per year a plant usually flowers during a period of 2 months, producing 10-20 inflorescences, each with up to 30 flowers. In one day 1-3 flowers per inflorescence open early in the morning and close in the afternoon. If pollination does not occur the flower withers and drops in 1-2 days. The fruit reaches its maximum length about 6 weeks after fertilization, and ripens 7-9 months after flowering.

Other botanical information

Although several vanilla qualities or grades are distinguished in commercial trade, no formally named cultivars of V. planifolia are known. Perhaps the botanical variability has remained rather limited in plantations because propagation has been mainly vegetative. Nevertheless, in Indonesia at least 7 morphotypes or types are known, i.e. Chili, Madagaskar, Malang, Ungaran Daun Tipis, Ungaran Daun Tebal, Anggrek, and Gisting. All types are susceptible to Fusarium, but Gisting shows highest tolerance. Anggrek is most productive, but Gisting has the highest number of flowers per plant and number of bunches per vine.

The genus Vanilla P. Miller comprises about 100 species, distributed pantropically, most occurring in tropical America. Numerous species have slightly aromatic fruits but only a few are or have been used as substitutes for vanilla:

• V. abundiflora J.J. Smith. Known from South-East Asia - see Minor spices.

• V. gardneri Rolfe. Much like V. pompona but leaves half their size, and smaller flowers and fruits. It occurs in Brazil and is called Brazilian or Bahia vanilla. It is occasionally used as an adulterant of true vanilla.

• V. phaeantha H.G. Reichenb. Like V. planifolia but with much larger flowers and shorter fruits (up to 7.5 cm long). It occurs in Florida, the Bahamas and the Antilles and has been cultivated because of the aromatic fruit. It is most important now for its resistance to Fusarium root-rot disease of vanilla.

• V. pompona Schiede. Like V. planifolia but with larger leaves (10-30 cm × 4-10 cm), larger and more fleshy flowers, and shorter and thicker fruits (15-17 cm × 2.5-3.3 cm). It occurs in Central America, northern South America and the Lesser Antilles and is also occasionally cultivated. It is called West Indian vanilla, great vanilla or pompon and is perhaps the most used natural substitute of real vanilla. The fruit is also used to extract heliotropin which is used in the perfume industry and to flavour tobacco. As a spice it is much less important than V. planifolia and much cheaper. The fruits are harvestable in a different season than those of true vanilla, which also makes cultivation interesting; however, they are more difficult to dry.

• V. tahitensis J.W. Moore. Less robust than V. planifolia, with more slender stems, narrower leaves (12-14 cm × 2.5-3 cm), smaller fruits (12-14 cm × 9 mm) tapering towards both ends, not splitting open at maturity. It is indigenous to Tahiti and also cultivated there and in Hawaii (Tahitian vanilla). The fruits have a lower vanillin content, but the aroma is sweeter, best suited for cosmetics.

Ecology

Vanilla thrives in warm, per-humid or humid climates without a pronounced dry season. Temperatures may range between 21-32°C, with an average of 26°C. Rainfall is preferably up to 2000-2500 mm/year and evenly distributed. A drier period of 2 months favours flowering. Such climates are found e.g. on tropical islands between 20°N and 20°S. In Java (Indonesia), vanilla can be grown up to 400-700 m altitude. Rainfall should not be too heavy while the fruits are ripening.

Vanilla requires a light soil with good drainage, rich in Ca and K, with a thick surface layer of humus or mulch in which the roots can spread, with pH between 6-7. The plantation should preferably be on a slight slope. Partial shade is necessary and can be provided by shrubs or small trees up which the vines are grown.

Propagation and planting

Commercial vanilla is propagated by stem cuttings. These should be taken from healthy, vigorous vines. It is advisable to keep separate "mother vines” for propagation. These should be prevented from flowering. If enough planting material is available, long cuttings of 1.50 m are preferred. Cuttings should be taken during the drier period of the year when growth of the mother-vines has slowed down. The leaves at the base of the cutting should be removed, because they start rotting in the soil. Cuttings are planted directly at the foot of a support tree at a spacing of 2 m × 3 m, with the lower part with 3 nodes buried in the humic layer and mulch. Because of their succulent nature, cuttings may be stored for up to 2 weeks.

Vanilla requires support to climb on, usually offered in the form of a tree. The ideal support tree is easily propagated, strong enough to carry the heavy vines, well-anchored in the soil to withstand strong winds, and not a quick grower to avoid heavy pruning. It should preferably have sufficient lower branches, as this makes it easier to train the vines to hang down over them. Often legumes are used for this. In Bali (Indonesia), coffee is used as support. It is, however, not advisable to use commercial crops like coffee, mango and avocado as support, since the roots of vanilla may be damaged by the operations to harvest these crops. In Madagascar, Gliricidia sepium (Jacq.) Kunth ex Walp. is used as a support tree. Cuttings of the support tree are planted 1 year in advance of the vanilla cuttings at a spacing of 1.5-2.5 m × 3 m. Vanilla can also be grown up posts or trellises.

Shade should be provided in the first place by the support tree. Often, other trees are planted as well to provide additional shade when needed. Light should be filtered in such a way that the level of radiation is still adequate for photosynthesis. Air circulation near the vines should be sufficient to have a drying effect, preventing the spread of fungal diseases. Shade trees used include Albizia lebbeck (L.) Benth., Inga edulis Mart. and Cocos nucifera L.

Tissue culture techniques have been developed for rapid and large-scale multiplication of disease-free vines of V. planifolia. Multiple plantlets are produced by culturing the aerial root tips of vanilla on media supplemented with various growth regulators (auxins and kinetins). This technique can be used for producing clonal material of V. planifolia for use in plantations and in physiological experiments. Tissue culture methods using nodal segments for in vitro propagation have also been reported.

Only for breeding purposes does it pay to follow the difficult path of growing vanilla from seed. Fruits should be picked just before or as they split. Seeds are then washed clean and transferred to a sterilized nutrient medium. Temperature must be kept rather high (30°C). Under these circumstances vanilla will germinate in 1-2 months. The young seedlings should be transferred every 2 months. After a year seedlings are transferred to soil. After another year the then 2-year-old plants can be planted in the open.

In vitro production of active compounds

Attempts have been made to produce secondary vanilla metabolites (vanillin, in particular) from V. planifolia cell suspension cultures. Callus culture is developed from green bean tissue, from aseptic explants or shoots, or from growing plant shoot tips and seeds, and this is subsequently used to form a suspension culture. However, the production of natural vanilla flavour using biotechnology is still experimental.

Husbandry

New shoots of the vanilla cutting planted at the foot of a support tree are trained along its branches to encourage them to develop at a convenient height for pollination and harvesting. When shoots reach a length of about 2.5 m, they are carefully detached from the branch so that they may hang down. The tip (about 10 cm) of the vine is cut off 6-8 months before the flowering season, to encourage the production of inflorescences. New vegetative shoots on the apical part of the hanging vine are pruned, those on the basal part of the hanging vine are trained along the branches of the support tree. The latter will be the productive vines for the next season. At the beginning of the flowering season inflorescences will emerge from the leaf axils at the apical part of the hanging vines. These vines are removed after harvesting. Pollination is absolutely necessary to obtain fruits. In its centre of origin vanilla is pollinated by bees (Melipona spp.) and possibly also by humming birds. In the production areas pollination is carried out by hand with a small stick. The flower is held in one hand and the labellum is pushed down with the thumb, releasing the column. The stamen cap is removed by the stick held in the other hand which exposes the pollinia. The thin flap-like rostellum is then pushed up under the stamen with the stick and, by pressing with the thumb and the finger, the pollinia are brought into contact with the sticky stigma to which the pollen mass adheres. Per day a worker can pollinate on average 1000-3000 flowers. Hand-pollination allows the number of fruits per inflorescence and thus also per plant to be regulated. Only basal flowers of an inflorescence are pollinated, resulting in 4-6 fruits per raceme that develop into straight beans. On average a 4-5-year-old plant should not be allowed to bear more than 100-150 fruits, as otherwise it may become unproductive in later years.

Vanilla not only requires a soil with a high organic matter content but also an adequate supply of mulch. The best mulch is a mixture of grasses and legumes. Fruit-bearing vanilla should be mulched especially well. Clean-weeding of the vanillery is not recommended, but rank growth of climbers and other weeds should be controlled.

Chemical fertilizers are seldom used, although adequate application will give a good crop. However, mulched plantings give the best quality vanilla, particularly in terms of aroma.

Diseases and pests

The most serious disease of vanilla is root-rot or stem-rot disease, caused by Fusarium oxysporum f.sp. vanillae. The disease is usually controlled by fungicides or, in Indonesia, by incorporating clove leaves into the soil. Clove leaf oil contains eugenol which appears to inhibit radial growth and sporulation of the pathogen. Anthracnose (Glomerella vanillae) attacks all aerial parts of the plant, and is found in all vanilla-producing countries. It is favoured by overshading and humid conditions, so the best control is to decrease shading. Brown spot disease (Nectria vanillae) can also affect all aerial parts. Old and weak plants are especially vulnerable. Mildew (Phytophthora sp.) may damage all parts of the plant. High humidity facilitates the spread of the disease. There is no cure for it; infected plants should be removed and burnt. Cured vanilla fruits may also be affected by mildew.

Vanilla is attacked by a number of insects but none of them causes great losses. The most serious pests are snails (Thelidomus lima in Puerto Rico, Achatina fulica in Madagascar) and slugs (Veronicalla kraussii in Puerto Rico). Chickens cause much damage by scratching among the mulch and in so doing tearing and exposing the roots.

Harvesting

The fruits are hand-picked 7-9 months after flowering. The best moment of harvesting is when the fruits are still dark green, with only the tip turning yellow. If they are harvested earlier the aroma develops poorly; if harvested later they split and give poor quality. Harvesting is done rotationally over a period of 2-3 months.

Yield

Yields may fluctuate from year to year. A vanillery may yield 2.5-4 t/ha per year of fresh fruits (being 500-800 kg/ha of cured beans) during a productive crop life of about 7 years (out of a total crop life of about 10 years), but much lower yields are reported.

Handling after harvest

The curing process should begin within a week after harvesting. It consists of blanching, fermenting and drying, during which 70-80% of the water is lost and the typical aroma develops. Fruits are immersed once (occasionally twice) in hot water for 30-60 seconds. The fruits are then stored for 24-48 hours in cloth-lined containers for sweating and to start fermentation. Then, for a period of 3-5 days beans are exposed to the sun during day-time on a scaffold and stored during the night. The beans are then conditioned in closed containers, where they develop the full aroma during 2-3 months. The cured beans are graded, smoothed and straightened. Finally, they are exported in sealed tin boxes. Good-quality cured beans should be dark brown, long, flexible, oily, smooth and aromatic.

In Mexico, the curing process takes 5-6 months: sun-drying takes at least 2 months and then the beans are kept in boxes for about 3 months.

At least four major commercial types of vanilla can be distinguished: the Bourbon vanilla (grown in Madagascar, Comores and Réunion), the Java vanilla (grown in Java in Indonesia), the "Bourbon-like” vanilla (mainly grown in Bali in Indonesia) and the Mexican vanilla. Bourbon vanilla ranks top in terms of quality. The major quality components are: flavour profile, natural vanillin content, bean length, moisture content, appearance, colour and presentation. Vanilla grown in Indonesia ranks fourth (after the product from the three Bourbon-producing countries) because of lower natural vanillin content and less attractive flavour profile. The improved cropping and curing practices recently adopted in Indonesia have led to an improvement in the overall quality of its vanilla beans. This is why in recent years the Malagasy and top-of-the-line Balinese beans have been increasingly seen as the leading vanilla types by the world's major users.

Genetic resources

A germplasm collection is held at the Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), Costa Rica. It comprises about 30 accessions from various countries in Central America.

Breeding

One of the main breeding objectives is to obtain resistance to root-rot disease. The resistant V. phaeantha H.G. Reichenb. is a promising species in this respect. Breeding programmes carried out until 1974 at the Vanilla Research Station of Antalaha (Madagascar) were not very successful. No new breeding breakthroughs have been reported so far.

Prospects

On the world market there is an increasing demand for natural flavouring substances. It is expected that this will favour the demand for natural vanilla. Supply currently lags behind demand, and therefore prices are increasing. Vanilla is a promising crop for different parts of South-East Asia, especially as a high-value crop for areas with high population pressure (e.g. Bali in Indonesia).

Literature

• Asnawi, R., 1993. Produksi beberapa tipe panili (Vanilla planifolia Andrews) [Productivity of several vanilla types (Vanilla planifolia Andrews)]. Buletin Penelitian Tanaman Rempah dan Obat 8(1): 52-55.

• Asnawi, R. & Hasanah, 1992. Resistensi beberapa tipe panili terhadap Fusarium oxysporum [Resistance of several vanilla types to Fusarium oxysporum]. Pemberitaan Lembaga Penelitian Tanaman Industri 18(1-2): 49-51.

• Blarel, B. & Dolinsky, D., 1995. Market imperfections and government failures: the vanilla sector in Madagascar. In: Marketing Africa's high value foods: comparative experiences of an emergent private sector. Kendall/Hunt Publishing Co., Dubuque, Iowa, United States. pp. 255-318.

• Bouriquet, G., 1954. Le vanillier et la vanille dans le monde [The vanilla plant and product in the world]. Editions Lechevalier, Paris, France. 739 pp.

• Bundschu, I., 1987. Das grüne Gold: kleinbäuerliche Vanilleproduktion auf Bali (Indonesien) [The green gold: vanilla production by smallholders on Bali (Indonesia)]. Tropenlandwirt 88: 97-111.

• Dequaire, J., 1976. L'amélioration du vanillier à Madagascar [The improvement of vanilla in Madagascar]. Journal d'Agriculture Tropicale et de Botanique Appliquée 23: 139-158.

• Jarrett, R.L. & Fernandez, Z.R., 1984. Shoot-tip vanilla culture for storage and exchange. IBPGR/FAO Plant Genetic Resources Newsletter 57: 25-27.

• Philip, V.J. & Nainar, S.A.Z., 1986. Clonal propagation of Vanilla planifolia Andr. using tissue culture. Journal of Plant Physiology 122: 211-215.

• Purseglove, J.W., Brown, E.G., Green, C.L. & Robbins, S.R.J., 1981. Spices. 2 volumes. Longman, Harlow, Essex, United Kingdom. Vol. 2. pp. 644-735.

• Ranadive, A.S., 1994. Vanilla - cultivation, curing, chemistry, technology and commercial products. In: Charalambous, G. (Editor): Spices, herbs and edible fungi. Developments in Food Science 34. Elsevier Science Publishers, Amsterdam, the Netherlands. pp. 517-577.

Sources of illustrations

Westphal, E. & Jansen, P.C.M. (Editors), 1989. Plant Resources of South-East Asia. A selection. Pudoc, Wageningen, the Netherlands. p. 271.

Authors

• J.T.G. Straver