General description
Vanilla is one of the most famous tropical spices in the world and is ranked third after saffron and cardamom as flavorings. Scientifically known as Vanilla planifolia Andrews (commonly known as Bourbon vanilla), it is a native orchid of Southeast Mesoamerica, Mexico.
This species is known for producing the highest quality and delicate popular flavor, vanilla. Vanilla tahitensis J. W. Moore and Vanilla pompona Schiede are two other economically important species of Vanilla. The other commercial vanilla plants are native to and grown in Tahiti and the Caribbean, respectively. Vanilla tahitensis produces vanilla that is more floral and fruity than Bourbon vanilla, while Vanilla pompona produces vanilla that is slightly similar to Bourbon vanilla but with a slightly different flavor profile.
Vanilla belongs to the Orchidaceae family, which contains over eight hundred genera distributed in more than twenty-five thousand species. Madagascar is the largest producer in the world, accounting for about three thousand tons per annum. Today, vanilla is widely cultivated in Madagascar, Indonesia, Uganda, the Comoros, Tahiti, Papua New Guinea, India, Mexico, and many other tropical countries.
The members of this genus are vine-like climbing orchids with stems that can reach lengths of up to one hundred and twenty feet. Vanilla is a climbing, perennial, angiosperm, monocot plant. It has a simple or branched, cylindrical, flexible green stem. There are about one hundred species distributed throughout tropical and subtropical regions of the world.
Horticultural and cultivation practices
Vanilla grows well in the presence of support and shaded conditions, but not in thick shading. Thick shading produces vines with smaller leaves, thin stems, and reduced flowering and fruiting. Vanilla usually cultivates well in hot and moist climates with infrequent rainfall. The optimal growth temperature ranges from twenty-one to thirty-two degrees Celsius. Ideally, gently sloping land with dappled light, thick surface layer, and adequate drainage facilities on high lands up to about 600 meters above mean sea level could be the best cultivation land for vanilla. The growing media is the substrate that is rich in humus and nutrients, with a soil pH between 6 to 7.
The vanilla vine is not a parasite but an epiphyte, which winds itself around other shrubs and trees for support but does not nourish itself on the sap of its hosts. It has a preferred host plant depending on the region it grows. For instance, the host plant for vanilla in Madagascar is Landolphia, whereas the host plant in Mexico is Swietenia. This is probably due to the volatile compounds produced by the host and the canopy that provides optimal shading for the vanilla in that country. The fleshy leaves are up to eight inches long and two inches broad. The leaves are arranged alternately along the stem, are flexible, subsessile, elliptical, and lanceolate. The plant has a bunch of fifteen to twenty pale yellow inflorescences, which sprout in the armpit and are short, about 2 and 2.5 inches (when the flower successfully opens).
Generally, 6 to 8 flowers per raceme are pollinated to ensure a minimum yield of 4 to 5 fruits per raceme at acceptable quality. It will usually take two to three years for vanilla vines to blossom after cutting and planting with optimal horticultural practices. The fruit is ready to be harvested roughly 8 to 9 months after pollination when the distal point of the fruit changes from green to yellow.
Vanilla produces several fragrant and large showy flowers that open progressively. Several factors promote flowering throughout the cultivation period, such as water stress caused by drought, cool autumn temperatures in Mexico that stimulate the development of lateral floral buds by breaking the plant’s apical dominance, and horticultural management practices like pruning of apical tips and different irrigation techniques. However, the vanilla flower is short-lived.
This orchid requires special growing conditions and requires pollination by hummingbirds (less effective due to the floral structure) and specialized insects, which are Melipona bees, known as stingless bees. Due to the limited distribution of pollinators in nature, manual pollination is used to pollinate vanilla flowers within twelve hours of opening. Each flower blossoms only for a day as it opens in the early morning and closes in the afternoon, whereas unfertilized flowers wilt within a day. The successfully pollinated flowers are followed by capsules with large seeds.
The seed pod, which is the source of vanilla flavoring, is linear and flat with a cone-shaped termination (12 to 35 cm long and 5 to 9 mm in diameter). Vanilla planifolia flowers throughout the year. The seed pod is wrinkled along the fruit and sometimes covered with small crystals of vanillin as it ages and exudes a strong odor. The seed pod bears about one hundred thousand seeds of 0.25 to 0.32 mm in diameter.
Vanilla plants grow well when potted in a mixture similar to the media used for Cymbidium orchids, and they require something to climb on. They thrive in bright filtered light and cannot tolerate strong sunlight, so care should be taken to avoid exposure to direct sunlight. Regular watering and fertilizing are necessary for optimal growth, and the plants typically do not flower until they have reached a large size.
Propagation of vanilla plants is typically done through stem cuttings, making vanilla one of the most labor-intensive agricultural products cultivated in the world. Conventionally, the plants are propagated by taking vine cuttings with four nodes that have been pretreated with plant growth regulators and then planted in polyethylene bags filled with well-drained substrate.
Vanilla plants were previously endangered due to overutilization and deforestation, which led to the loss of origin within years. However, with the help of plant tissue culture, vanilla is now widely produced through micropropagation to ensure the supply meets the demand of the trade market for this cash crop. Additionally, tissue culture can be used to induce in vitro vanilla seed germination, further expanding the possibilities for vanilla production.
Pest, disease, and postharvest management
All parts of the vanilla plant are vulnerable to pest attacks. White grubs have been found to cause significant damage, followed by vanilla bugs and shoot and leaf webbers, while others are not of economic concern. Several natural enemies, including parasitoids like Euplectrus sp., Glyptapanteles sp., Aprostocetus sp., Chelonus sp., and Uropoda mites, have been associated with controlling vanilla pests.
Various fungal infections can be found in vanilla plantations, including anthracnose caused by Calospora vanillae, fruit and root rot caused by Fusarium sp., fruit rot caused by Phytophthora sp., root rot caused by Colletotrichum sp. and Gloralla vanillae. Additionally, common infections such as black rot, Sclerotium rot, rust, and viral infections such as cucumovirus, Potexvirus, Tobamovirus, and potyvirus can affect the plant.
As the quality of vanilla beans is critical, the best postharvest management practice is to cure the beans as soon as possible after harvesting. The storage conditions for cured beans should be controlled for optimal temperature, humidity, and gas composition, and appropriate packaging should be used to ensure the beans remain fresh.
Nutritional values and downstream products
Vanilla is a highly valued spice with a long history of use by various indigenous groups such as the Mayans, Aztecs, and Totonacs. Besides being used as medicine and tribute to the gods, vanilla has been employed as a fragrance and flavoring agent in numerous culinary applications. The unique flavor and aroma of vanilla result from a complex series of biochemical and enzymatic changes that take place during the curing process of the vanilla pod, which transforms around two hundred compounds into the characteristic flavor and aroma of vanilla.
Vanillin, the most important flavor compound in vanilla, is a key component of cured vanilla pods, comprising approximately two percent of the dried weight of the pod. Isolated vanillin appears as a white needle-like crystalline powder with an intensely sweet, creamy, and very tenacious vanilla-like odor. Although artificial vanillin can be synthesized at a much lower cost, the natural vanilla pod’s price can range from $30 to $120 per kilogram, depending on the quality influenced by climatic conditions, economic, and political decisions. Given the labor-intensive nature of vanilla cultivation and processing, the production of vanillin through biotransformation offers an alternative to the costly extraction of vanilla pods.
Green vanilla beans are almost odorless and develop a faint phenolic odor as they mature. The complex aroma of vanilla is achieved through the process of curing, which involves blanching, repeated sweating and drying cycles, and conditioning in airtight containers for several months. The curing process is not vanilla extraction for flavoring, and the specific steps and conditions involved can vary from country to country. After sorting and grading, the cured beans are ready for extraction, which yields various downstream products such as vanilla extract, vanilla powder, and vanilla paste that are widely used in the food industry.
Vanilla is the only orchid grown for food purposes, owing to the fragrant fruit it generates – the vanilla pod. Vanilla is used extensively as a flavoring agent in a broad range of foods and confectionery, with approximately sixty percent being used in beverages, thirty-three percent in perfumes and cosmetics, and seven percent in pharmaceuticals.
In the food industry, vanilla is used to flavor a variety of desserts such as biscuits, cakes, drinks, sauces, candies, and ice creams. It is also used to flavor other foods, beverages, and drinks like coffee, soft drinks, whiskey, and some liquors. Vanilla has been used in some cuisines, like vanilla sauces for meats or combined with chilies. Additionally, vanilla seeds have limited uses and are usually used for the decoration of ice cream and custard.
Moreover, vanilla extracts are extensively used in aromatherapy for helping to relieve fatigue, enhancing mood, improving food intake, and reducing nausea and vomiting in patients undergoing chemotherapy. The bioactive compounds found in vanilla have antioxidant and antimicrobial activities. Its calming aroma makes it one of the best essential oils used in spas and massages. Vanilla has also been used to mask unpleasant tastes, especially in medicines for children. Additionally, vanilla-derived compounds can be safely used in children’s toys to mask unpleasant notes associated with rubber and plastic items. The perfume industry also extensively uses vanilla due to its aromatic characteristics.
Further readings:
Havkin-Frenkel, D., & Frenkel, C. (2006). Postharvest handling and storage of cured vanilla beans. Stewart Postharvest Review, 4(6), 1-9.
Havkin-Frenkel, D., & Belanger, F. C. (Eds.). (2018). Handbook of vanilla science and technology. John Wiley & Sons.
Cameron, K. (2012). Vanilla orchids: natural history and cultivation. Timber Press.
Odoux, E., & Grisoni, M. (2010). Medicinal and Aromatic Plants—Industrial Profiles.
Priefert, H., Rabenhorst, J., & Steinbüchel, A. (2001). Biotechnological production of vanillin. Applied Microbiology and Biotechnology, 56, 296-314.
Singletary, K. W. (2020). Vanilla: potential health benefits. Nutrition Today, 55(4), 186-196.
