The tonka bean is the seed of Dipteryx odorata, a legume tree in the neotropics, of the Fabaceae family. The seed is black and wrinkled in appearance, with a smooth brown interior. It is known mostly for its fragrance, which is reminiscent of vanilla, almonds, cinnamon, and cloves: it has sometimes been used commercially as a substitute for vanilla. It is also sometimes used in perfume and is commonly used in tobacco.

The seed contains coumarin, and for this reason its use in food is banned in the US by the Food and Drug Administration (FDA). Coumarin is an anti-coagulant and can be lethal in large doses. Many anti-coagulant prescription drugs are based on more powerful forms of coumarin.

To liberate the coumarin, the beans are processed by soaking in alcohol (rum) for 24 hours and drying, whereby a fermentation process takes place. Afterwards, the coumarin content may be as high as 10%. Coumarin crystals are visible under the epidermis of the seed.

The plant has its origin in Northern South America (Guyana, Orinoco region). Main producers today are Venezuela and also Nigeria.

The word tonka is taken from the Galibi (Carib) tongue spoken by natives of French Guiana; it also appears in Tupi, another language of the same region, as the name of the tree. The old genus name, Coumarouna, was formed from another Tupi name of the tonka tree, kumarú. The latter also lies behind the name of tonka's main constituent, coumarin.

The use of tonka beans (which was never high), has further decreased, since coumarin is suspected to be poisonous and carcinogenic. In spite of its hypnotic fragrance, the spice does not get mentioned often in cookbooks. Some books suggest adding minute amounts of it to the dough of cakes or cookies; sweets based on coconut, walnuts or poppy are another possible field of application. Lastly, tonka beans are sometimes suggested as a substitute for bitter almonds, especially in countries where usage of bitter almonds is restricted or prohibited by national food laws. Tonka makes an even better substitute for the Middle Eastern mahaleb cherry kernels. It was formerly used as a flavouring in snuff.

External links

• CFR Title 21 Code of Federal Regulations section prohibiting coumarin and tonka beans
• Spice Pages: Tonka Beans

Trees | beans | legumes | Flora of Guyana

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