From Plant Resources of South-East Asia No 13: Spices, PROSEA Foundation
by J. T. G. Straver
Taxon
Vanilla planifolia H.C. Andrews
Protologue
Bot. repos. 8: pl.
Family
Orchidaceae
Chromosome Numbers
2n = 25, 26, 28, 30, 31, 32.
Synonyms
Vanilla mexicana P. Miller (1768) p.p., Vanilla viridiflora Blume (1825), Vanilla 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).
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.
Botany
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 x 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 x
1-1.5 cm; 2 upper petals resembling the sepals but slightly smaller,
labellum (lower petal) trumpet-shaped, 4-5 cm x 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 x 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 Vanilla 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:
- Vanilla abundiflora J.J. Smith. Known from South-East Asia - see Minor spices.
- Vanilla gardneri Rolfe. Much like Vanilla 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.
- Vanilla phaeantha H.G. Reichenb. Like Vanilla 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.
- Vanilla pompona Schiede. Like Vanilla planifolia
but with larger leaves (10-30 cm x 4-10 cm), larger and more fleshy
flowers, and shorter and thicker fruits (15-17 cm x 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 Vanilla 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.
- Vanilla tahitensis J.W. Moore. Less robust than Vanilla planifolia,
with more slender stems, narrower leaves (12-14 cm x 2.5-3 cm), smaller
fruits (12-14 cm x 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 x 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 x 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 Vanilla 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 Vanilla 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 Vanilla 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 Vanilla 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.
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