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22-11-2010

TREND: The Tonka bean is conquering the chocolatier's workshop

The attraction of the forbidden fruit

Chocolates with a spicy filling are part of a taste trend which first arrived in Belgium a few years ago, after seducing France. According to the trendsetters of the day, this taste trend had already had its day. Nevertheless, the choice of spices is not always directly affected by trends. The controversial tonka bean is a perfect example. If it is controversial – and perhaps that is precisely what makes it trendy – it is because it is on the list of plants which cannot be used either as a food or in food. This needs some explanation.

Origin and shape
Tonka beans were introduced into South America, or more precisely into Venezuela. The trees are also grown in Nigeria, in West Africa. Each fruit of the tonka tree contains 1 seed: the tonka bean. Tonka beans are long and narrow in shape, black and wrinkled on the outside and brown on the inside.

Transformation
After being harvested, the tonka beans are dried. They are then soaked in alcohol for 24 hours and dried again. During this process, fermentation occurs: on the outside a fine veil of coumarin crystals forms, the principal flavour of tonka beans.
Several varieties of tonka bean exist. One of them is a flavouring which is highly prized in desserts. This variety is soaked in rum rather than alcohol.
Ever since chocolatiers have been increasingly incorporating spices into their chocolates, the tonka bean has managed to tempt them.

Taste and odour
After soaking in rum, the tonka beans have a taste somewhere between the sweetness of vanilla and the bitterness of almonds. Obviously the flavour of the rum is also present. This combination of tastes makes the tonka bean an ideal flavour for iced desserts, patisserie and pralines. Its smell is reminiscent of vanilla, almond, cinnamon and clove. Which is why the tonka bean is also incorporated into perfumes and tobacco mixes.

The tonka bean goes particularly well with the following dishes and ingredients:
• crème brûlée
• tonka bean ice cream
• biscuit or cake mix
• coconut-based sweets

Forbidden fruit
We said earlier that the use of tonka beans in food and dishes is controversial. This is because these beans contain coumarin. The plus side of coumarin is that it gives the tonka beans their typical taste. The disadvantage is that the tonka bean contains up to 10% coumarin. Coumarin can be dangerous to health on several counts. It thins the blood and, when it is absorbed in high doses, can damage the liver and kidneys and cause headaches. Furthermore, coumarin is suspected of being not only toxic, but also carcinogenic. This is why use of the tonka bean has been prohibited in the United States since 1954. Since then, its already low usage has reduced still further. In Belgium, it was not until 1997 that the use of tonka beans was controlled. In the Royal Decree of 29.08.1997, tonka beans are shown on the list of dangerous plants which cannot be used as or in food. This means that the use of the tonka bean in dishes is prohibited.

Only as flavouring
The kitchen doors therefore remain shut to tonka beans but (fortunately), there is a back door. In fact, article 2, paragraph 2 of the Royal Decree states that this provision does not apply to the production of tonka bean flavouring. This flavouring is used in ganache and caramel sweets. How is it done? The beans are broken or grated, the shavings are boiled with cream or milk, the mixture is allowed to infuse and then cooled in a closed recipient. The latter prevents the flavour from volatilising as well as ensuring that the other foods take on the flavour of the tonka bean. Filter carefully before use as the tonka bean is not edible.

Reprinted from: Chocolaterie (Confectioners) magazine

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