Sounds exotic and it is. But the tonka bean is also becoming increasingly popular in Europe. We at Plantura are investigating.
Tonka- the name already sounds like tropical forests, colorful flowers and confused chirping of birds and with this association you are not wrong at all. Because the tonka tree (Dipteryx odorata) is an imposing tree that is native to the tropical regions of the American continent. In fact, it has been cultivated in northern South America, the Amazonian rainforests, the Caribbean, and Guyana for centuries. The trees reach a proud height of up to 30 meters and have a wide canopy as a crown. The tonka bean lolls along them. Strictly speaking, this is not a bean at all, but the seed in the fruit of the tonka tree. But if you are now thinking of a colorful fruit, you are wrong in this case, because the color of the tonka fruit varies from gray to black and reaches a delicate size of about two to five centimeters. Even if the fruit does not know how to shine like gold, it is worth a lot to the inhabitants of its cultivation areas. Until 1940, the tonka bean was a common means of payment among the natives of Venezuela and to this day the tonka bean is worn as a protective amulet against illnesses or in the wallet as a good luck charm. The word "Tonka" comes from the Caribbean language of the native French Guiana and means the tree. In Spanish, the tonka bean is called "cumarú", which gives a reference to the ingredient coumarin. Originally, interest was more in the tonka tree, which was often felled because of its wood. This is not only extremely durable, but also special due to its eye-catching, dark to orange-red shimmering colour. In the meantime, however, the demand for tonka beans is also increasing, especially in the catering, as well as the food and cosmetics industry. This is probably due to the fact that it exudes a captivating aromatic-sweet scent, comparable to a bourbon vanilla.
Synonyms: Counarouna odorata, Dipteryx odorata, Coumarou or cumarú
Tonka Bean Cultivation
The tonka tree belongs to the legumes, more precisely to the legume family (Fabaceae).who also counts the pea. Even the tree's butterfly-shaped purple or pink flowers closely resemble those of a pea, and the late spring to late summer flowering timing is also characteristic of this plant family. After flowering, the mango-like fruit with leathery skin and tasteless pulp grows from the ovary. It contains a single, almond-shaped seed - the tonka bean. The aroma of the bean is similar to vanilla and the extracts are used both as a culinary spice and for therapeutic purposes.
Today, Nigeria and Venezuela are still the countries with the largest exports of tonka beans. The trees also grow in rather nutrient-poor soil and prefer sunny locations but require well-drained soil. Nevertheless, the tonka tree thrives best when it is cultivated in very humus-rich soil.
At the end of the 18th century, the first seeds of the tonka tree found their way to Europe and were cultivated in greenhouses in France. In our latitudes, it is extremely difficult to create the preferred climate for the tonka tree, even in a greenhouse, which is why we would only recommend its cultivation to professionals.
Harvest and Storage of the Tonka Bean
As soon as the fruits have ripened and fall from the tonka trees around May, the beans can be removed from the hard shell and collected. Ideally, you can achieve a yield of up to 15kg of tonka beans per tree. The tonka beans get their coveted rum aroma by soaking them in rum before they are dried for months. Drying results in the typical brownish-black and wrinkled skin of the tonka bean. The tonka bean should be stored dry and cool so that it retains its great aroma for a long time. A tightly closable can or a dark screw-top jar is best suited for this.
Ingredients and their effects
The most well-known ingredient in the tonka bean is coumarin, which comes from the lactone class of substances. It also gives fresh hay and woodruff its typically spicy smell. The average coumarin content is two to three percent, but peak values of up to ten percent can also be reached. Coumarin has long been suspected of being carcinogenic, damaging to the kidneys and liver. For this reason, the tonka bean was banned in Germany for a while. Since 1991, this ban has only existed in a restricted form. On the one hand, this is due to the fact that the carcinogenic effect only occurs when artificiallyproduced coumarin was detected in very high doses and on the other hand in South Africa the tonka bean is specially treated so that the coumarin content drops. Nevertheless, it is better not to exceed the maximum dose of 0.1 mg coumarin per kilogram of body weight. From an overdose of 500 mg per kg body weight, this substance has a toxic effect and causes severe headaches, vomiting, dizziness, lethargy, central paralysis, respiratory arrest and, in the worst case, coma. However, since only extremely small amounts are used in the kitchen (the aroma explosion is enormous), coumarin poisoning is unlikely.
Already among the natives of South America, the tonka bean was considered a natural remedy for body, mind and soul. In today's medicine, coumarin is used as a pain reliever and blood thinner. At the same time, it stimulates the production of serotonin in the body. Above all, alternative medicine makes use of the calming and relaxing effect and prescribes coumarin for insomnia and gastrointestinal complaints. Tonka bean essential oil has pain-relieving, anticonvulsant and warming properties for tense and sore muscles.
Ethanol is required to obtain coumarin, as it has only limited solubility in water.
Use in the kitchen
The tonka bean's unique aroma is often described as a combination of vanilla, almond, pear and even fresh hay. Exactly this scent was used for the perfume production for years. This unique aroma combination is now celebrating its entry into the kitchens of this world. Tonka beans are often used in the preparation of desserts to create a complex and unique vanilla flavor. But you can also boil them with milk or cream and use them to conjure up ice cream, chocolate or mascarpone desserts. But the tonka bean also gives hearty dishes such as mashed potatoes, sauces and soups that certain something.