VANILLA
SCIENTIFIC NAME: Vanilla planifolia
FAMILY: FAMILY: Orchidaceae
Text presented on Monday July 11, 1988 in Room 101, Casa del Prado, in Balboa Park, San Diego, California, to the member of the CRFG 20th Anniversary Meeting and International Rare Fruit Growers Seminar at the San Diego Potluck Dinner.
Vanilla is the seed pod of a typical tropical orchid. It is native to Mexico, Belize and Costa Rica. This very lovely plant belongs to the Orchidaceae family. The technical name of the species that has the best quality is Vanilla planifolia Andrews, which has two synonyms, Vanilla fragrans Ames, and Myrobroma fragrans Salisbury.
Another species, Vanilla pompona Schiede, known as West Indies or Tahitian vanilla, is commercial, but of much lower quality because its pods are shorter and much thicker than those of Mexican vanilla.
The Orchidaceae is one of the largest families of flowering plants, with several genera and 15,000 to 17,000 known species. The Vanilla genus includes approximately 90 species of branching and climbing vines, native to the tropical areas of the world, which, like all orchids, are highly appreciated and decorative. These vines are capable of climbing to great heights; I have seen them at or near the top of 60' trees.
Vanilla was cultivated by the native Totonaca tribe of Eastern Mexico Indians over 1000 years ago and was a favorite spice in the diet of pre-Columbian Indian tribes throughout what is now Mexico and parts of Central America.
When the Aztec emperor, Moctezuma, introduced Hernan Cortes, the Spanish conqueror of Mexico, to the plants used by the Aztecs, but then unknown to the Spaniards, one of these plants was vanilla. Moctezuma warned Cortes, so the legend goes, not to abuse vanilla because he would soon find himself the father of many children. The aphrodisiac properties of vanilla have not, to this date, been demonstrated.
The Spanish Conquistadores liked the fragrance of vanilla and soon had it in the King's kitchens in Spain, from where it gained admission to the other kingdoms throughout Europe. It was then transported by various European colonizers to tropical countries, most of which are islands, such as Madagascar, Reunion, Mauritius, Nossi-Be, Comores, Seychelles, Sumatra, Java, Timor, Southern India, Ceylon, Tahiti, Martinique, Guadeloupe and others. Vanilla did not prosper in all these areas, and at present it is grown on a commercial scale mainly in the Malgache Republic (formerly known as Madagascar), Mexico, Indonesia, Reunion, Mauritius and Tahiti.
It is generally accepted that vanilla was grown originally by the Totonaca tribe in the vicinity of Misantla, in North Central Veracruz. At present, it can be found growing wild or under intense and highly sophisticated commercial cultivation in a relatively small zone on the East Coast of Mexico, of which the Papanitla area of North Central Veracruz is considered the best, although it is being tried elsewhere, but on a small scale.
Mexican vanilla is considered by experts as the best in quality, size, and fragrance. It generally comes from Vanilla planifolia. The next best commercial quality is that from the Malgache Republic, Reunion and Mauritius commonly known as Bourbon vanilla. Third in quality classification is the vanilla from Indonesia (mainly Java) and French Polynesia, produced mostly from Vanilla pompona.
Vanilla is a very popular spice used as a flavouring agent in baking, confectionery, ice cream, liqueurs, perfumes; in pharmaceuticals; as a reagent in analytical chemistry; and in the preparation of the concentrate of a well-known cola drink.
Vanilla is a labor-intensive crop. The cost of producing it is high, and consequently, so is its price. For several centuries, the cured pods of natural vanilla were the only source of vanillin, which is the product that has the delicate and unique aroma of vanilla. The main flavouring constituents of natural vanilla pods are coniferin and two ferments which are transformed to vanillin during the curing process of vanilla pods.
Synthetic vanilla, which is technically a vanillin, is much less expensive than the natural vanilla. For many years, synthetic vanillin almost totally replaced the natural product, although natural vanilla contains small quantities of various aromatic substances which give it distinctive qualities that the synthetic vanilla does not have.
The advent of synthetic vanillin rendered almost uneconomical the production of natural vanilla, and many groves throughout the world, and in Mexico in particular, were abandoned. However, a recent controversy about the possibility that synthetic vanillin may cause cancer in human beings has restored the consumer demand for the natural product, which is once again in the limelight. A world-famous cola drink had been using synthetic vanillin, but, because of the controversy, it has now reverted to the natural product. Almost all the natural vanilla now produced in Mexico is being used to produce this cola drink and, in spite of the recent increase in vanilla production in Mexico, it is still difficult to find it commercially.
Vanilla plants prosper best in tropical areas with a rainy season of approximately nine months yearly and a dry season of three months, necessary for the adequate ripening of the capsules. An annual rainfall of 1800 to 2400 millimeters is considered best, with a relative humidity of 70 to 80% and daytime temperatures of 20 to 25°C. In Mexico, vanilla is grown from 50 to 400 metres above sea level.
Soil for vanilla plantations should be light, with good drainage and with a minimum of 2.5% organic matter. Soil texture should preferably be loamy sand, sandy loam, loam or silty loam, although the texture is not very important, since the terrestrial root system of vanilla plants is very shallow. The root system is both epiphytic and terrestrial. The epiphytic or aerial roots are relatively long appresoria that anchor the vine on the tutor. They originate from the nodes in the stems and are seldom branched, light grey to tan with green to greenish-white tips formed by rapidly dividing and very active meristematic cells which can easily absorb water, and which owe their greenish colour to the chlorophyll they contain, which allows for a certain degree of photosynthesis in these tips. The central core of these roots is surrounded by the velamen, an extra layer of dead cells, which protects the vital tissues of the roots from drought, heat, and excessive sunlight, acting as a 'weather jacket'.
The same roots can grow down and bury themselves into the soil, then becoming terrestrial roots. But the most common terrestrial root systems growing into the soil originate from nodes in the stems that are buried in the soil. They are identical to the epiphytic roots, but they lose their green tips and grow horizontally to 30 or more feet (about 10 meters) from the crown in the upper 10 to 12 inches of soil (20 to 25 cm). They are generally much thicker than the aerial roots and are almost always branched.
The vines are dark green, fleshy, and high-climbing, with a diameter of 5 to 13 mm and internodes 8 to 15 cm long. They will be prostrate and decumbent until they find a tutor, then becoming ascending. The leaves are thick and fleshy, 3 to 8 cm wide by 12 to 20 cm long, with parallel dark striations which become darker when the leaves dry.
Flowers are numerous, yellow-green, 4 to 6 cm long, borne in short axillary racemes. Sepals and petals are typical of most orchid flowers. The yellow lip has a paw joined to a footless column which bears the reproductive organs, stamens and pistil united. The flowers are narrow, trumpet-shaped with crenulated lobes.
The production of pods, which is the objective in vanilla groves, is determined by the pollination of the vanilla flowers. Although the flowers are autogamous, which means that male and female organs occur in the same flower, it is necessary to hand-pollinate each flower. Of course, some flowers pollinate by themselves, but the percentage is less than 1%. Self-fertilization is then very erratic, even though various genera of insects visit the flower.
The reproductive organs are located on the column in the center of the flower, which is surrounded by a dorsal sepal, lateral sepals, petals, outer lobes and central lobe. Pollen is produced in cells located at the tip of the pillinia, a thin membrane which tapers at its base to a slender stalk. Pollen masses are covered with another thin membrane or scale called the anther cap which, in commercial vanilla plantations, is broken or removed by hand with a sharply pointed piece of wood when the pollen is ripe, so that it will fall on the stigmatic cavity, which in Orchidaceae replaces the stigma or pistil of other plants, and which is covered by a sticky or gelatinous substance.
The hand-pollinization thus assures the fertilization of a much larger number of ovaries than through the natural process. It must be done between dawn and shortly after noon, since vanilla flowers open in the early morning shortly after dawn. They close a short time after noon, between two and three 0' clock in the afternoon. They are open for only a few hours of one day only. They do not open on the following day.
The hand-pollinization is a very delicate process. The anther cap must be removed very delicately by hand. Careful and experienced workers will hold the flower so that the pollen will fall on the stigmatic cavity which, as said above, is covered by a sticky or gelatinous substance. If the pollen misses this area, the flower will not be pollinated. Hand-pollinization of vanilla flowers is done during the entire flowering season, which lasts normally between three to five weeks in March or April.
The vanilla pods which develop when hand-pollinization has been successfully carried out, are three-sided, striate, 15 to 30 cm long (6-12"), fleshy and dehiscent if allowed to go to full maturity. They contain many thousands of extremely small seeds. Because of their tendency to split open and scatter their seeds, technically called dehiscence, vanilla pods must be harvested when they are almost ripe.
Until some years ago, traditional vanilla growers would plant the vines at the foot of forest trees in uncleared or lightly-cleared tropical forests, allowing the vines to climb freely. This made fumigations, pollinization, and harvesting very difficult. Yields, as a result, were very low. Although a few small growers still cling to the old system, the modern commercial groves are established with planted tutors on land that has been previously cleared and prepared.
Since vanilla is a climbing vine, it requires a tutor on which it can anchor itself through its aerial roots, called appresoria. In the establishment of a grove, tutors must be planted first and allowed to grow for a year-and-a-half or more. The most common planting system for tutors is 2.5 metres (about 8') between rows and 2.5 metres between trees in the row. A five-meter (about 16') wide service street is left every 10 to 20 rows of tutor trees. Besides serving as tutors, these trees shade the vanilla vines.
Once the young tutor trees are established to the required normal height of 3.5 to 4 metres, and pruned to encourage their lateral growth along the rows and not in the space between rows, two to three vanilla vines or stolons are planted in the soil around the base of each tutor and allowed to grow vertically to 1.5 or 2 meters maximum. When the vines reach this height, their tip is guided and fastened to a horizontal tutor branch in the direction of the next tutor in the row. Each vine has to be checked almost daily and refastened or trained, because the vines have a tendencey to curl upward seeking the light above the canopy of tutor trees.
If the vines were allowed to grow upward, the various tasks, such as pollinization, foliar fertilization, fumigation against many pests, harvesting, and others would be much more difficult.
One large vanilla grower has installed a permanent overhead irrigation system, to insure against the effects of a prolonged drought.
The present cost of establishing a vanilla grove with proper techniques, overhead irrigation tutors of correct varieties and vanilla plants that are healthy and productive, runs to about $25,000 per hectare (about $10,000 per acre) before the first sales income is received. This excludes the cost of land itself. The labor intensity of a vanilla plantation is a major factor in these high costs which tend to increase every year.
When pods are almost ripe, they are harvested one-by-one by hand. The harvesting of beans or pods starts in mid to late November and usually lasts until April and sometimes to mid-May. The pods are green when harvested and measure at least 6" long. The best commercial size is 10 to 12".
Harvested pods are taken quickly to the plant where they will be cured. The curing of vanilla pods is a complicated, precise, labor-intensive and lengthy process transmitted from generation to generation. In Mexico and in Java, curing is done by the "sweating" process which requires great care and patience, as well as a great amount of experience.
The pods, or beans, are patiently placed one-by-one and side-by-side on special hand-made racks, which are inserted in ovens at a temperature of 68°C (154°F) during three to four days. At the end of this process called "cooking", the pods, still in the same wooden racks, must be placed in direct sunshine during 100 full days. At the completion of this period, the pods are considered "cured" and can be stored for several years without fear of deterioration.
During the 100-day curing period, if rainy or cloudy days should interfere with this process, the racks and vanilla pods are again placed in the ovens where the temperature is now kept between 55 and 60°C (131 and 140°F).
The pods undergoing curing must not get wet at any time or they will lose the major part of their fragrance and commercial value. It must be remembered that in the areas where vanilla grows, tropical storms descend without much warning. When they threaten, all wooden trays must quickly and carefully be taken from the large outdoor drying patios to the necessary protection which is then provided by a very elaborate set of wooden scaffolds where the racks slide in. That is also where the racks are placed every night after the pods have received the amount of sunshine the owner of the plant considers adequate for that one day.
In the vanilla business, we know that 6 pounds of green pods will yield about one pound of cured beans. The quality of the vanilla after curing depends greatly on the care exercised during the curing process. Another important factor is the quality of the green pods before curing. For example, if the pods are harvested overripe, they will split open and their extremely small seeds will scatter. The resulting cured beans will have lost a substantial part of their characteristic fragrance.
A well-fertilized grove will produce quite a few racemes of flowers. On each raceme, one flower will open at a time. A modern grove will have about 1300 tutor trees per hectare (about 526 trees per acre). Such a grove will have between 3000 and 4000 producing vanilla plants per hectare (1200 to 1600 plants per acre). If the grove is fertilized adequately, kept free of weeds, with tutor trees kept correctly pruned and vanilla vines well-trained on tutor-tree branches, hand-pollination done in due time and by expert personnel, among other chores, during the flowering period there will usually be an average of 3500 flowers to hand-pollinate per hectare per day (about 1400 flowers per acre). Since flowers open an hour or two after sunrise and close at the latest three hours after noon, there are only a few hours to pollinate these flowers. A man with experience in hand-pollination of vanilla flowers can usually pollinate between 200 and 250 flowers in one daily time period. It usually takes these experienced persons less than one minute to pollinate the flower, plus time to move to the next. In a good grove, 14 to 20 men are needed per hectare (six to eight men per acre) for the pollination of flowers. If a flower is missed today, it will not open tomorrow, so it is lost. The pollinators are paid good wages because of their special skill, and frequently they prefer to be paid an average salary plus a bonus which they will earn on positive results, which means positively-pollinated flowers. A flower that is hand-pollinated adequately will show the start of a small pod just a few days after pollination.
Science is trying to substitute hand-pollination with a chemical pollination with a solution of 5 parts per million 2,4-D, sprayed on the open flowers. But this is still experimental. The results have not been satisfactory because the percentage of positively-pollinated flowers has been much lower than with hand-pollination. I have detected deformities in the vanilla plants and flowers which I have diagnosed as being attributable to the chemical spray.
A good and well-managed vanilla grove in Mexico can now produce between 2500 and 3000 kilograms of green pods per hectare (2200 to 2700 pounds per acre), which will yield 400 to 500 kilograms of cured vanilla beans (880 to 1100 pounds). Yields used to be much lower, but they are steadily increasing as owners are improving their methods and using sophisticated techniques in their groves.
DATE: July 1989
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