Kitchen Project #147: All About Tonka Beans

A new edition of DANGEROUS GOODS by Camilla Wynne

Hello,

Welcome to today’s edition of Kitchen Projects. Thank you so much for being here.

Today the brilliant Camilla Wynne is back with another installment of DANGEROUS GOODS (read licorice here and fruit pits here), where she investigates ingredients with a dark side. In this newsletter, Camilla tackles the aromatic Tonka Bean, complete with a recipe for fluffy, apricot enriched morning buns.

Over on KP+, the tonka trials continue with two gorgeous recipes - tonka bean custard creams (a recipe which she says is one of her favourites she’s made!) and the tonkamisu, a beautiful layered tart inspired by… well, you can probably guess. Click here to make it!

What's KP+? Well, it's the level-up version of this newsletter. By joining KP+, you will support the writing and research that goes into the newsletter (including the commissioning - and fair payment - of all the writers), join a growing community, access extra content (inc., the entire archive with 300+ recipes) and more. Subscribing is easy and only costs £6 per month or just £50 per year (equivalent to £4.10 per month). Why not give it a go? Come and join the gang!

Love,
Nicola

DANGEROUS GOODS #3: TONKA BEANS

by Camilla Wynne / @Camillawynne

2006. It had only been a few years—my first few years of working in fine dining post-pastry school—of rhapsodizing about my new favorite ingredient, when Alinea, a modernist Chicago restaurant, was raided by the FDA for having that same ingredient in their pantry. 

Photo by Claire Dinhut

In Montreal, north of the US border, I’d been blissfully unaware that the diminutive, wrinkly tonka bean I’d been microplaning into panna cottas and ice cream bases was banned outright in our neighboring country. Just as when I learned that my beloved liquorice had deadly properties, I was shocked that this delicious spice might kill me?! And yet, these two examples illustrate the haphazard manner in which potentially dangerous ingredients are controlled. Liquorice, readily available for purchase at nearly every market, actually has killed someone. Tonka beans, on the other hand, are banned but have never caused a recorded death, although they could in theory kill you if you ate many at once (30 beans can cause liver failure) or ingested a lot regularly. But so can alcohol—or even water if you manage to drink too much all at once. The dose, indeed, makes the poison. 

I hate to think of all the Americans who might’ve never tried tonka. When I try to describe the flavor of tonka beans to someone who’s never had the pleasure, I used to almost always say “vanilla almond latte.” Just a little brown bean, but so intoxicating on the tongue! Yet there was always something lacking in my description. I’ve heard “vanilla coffee marzipan,” but that’s just a different way of describing it the way I already was—though they both sound good, to be fair. It wasn’t until I cracked open the great tome that is The Penguin Companion to Food that I found the scent I couldn’t articulate—hay! Yes, hay like horses eat, although if that puts you off (though I can’t see why—have you ever smelled freshly mown hay??), sweet woodruff, a flowering perennial prized for its sweet smell, is a similar scent that describes it well. These aromas come from the presence of coumarin, an aromatic chemical compound also known as C₉H₆O₂.

Swirly tonka bean buns

That coumarin is actually the deadly bit of the tonka bean, inalienable from its fragrant allure. In large doses it messes with how your blot clots and can cause liver damage, hemorrhages and even paralysis of the heart. Tonka beans typically contain 1 to 3% coumarin, although they have been known to contain as much as 10%. Many other plants contain this compound, possibly as a chemical defense against predators, including sweetgrass, sweet woodruff, strawberries and black currants. Cinnamon, a wildly more popular spice than tonka, contains 1% coumarin in the cassia variety most commonly found for sale and in baked goods (true Ceylon cinnamon only contains about 0.004%). No one seems to be thinking of banning cinnamon, though! To be fair, you’d have to eat 2 grams (~¾ tsp) a day for about 3 weeks to experience deleterious effects, which is about 24 cinnamon cookies daily. It’s been pointed out that you’d likely have some other problems as well if you were eating 24 cookies a day (although it’s a good argument for shelling out the extra money for true cinnamon). And since tonka tends to be used in even smaller quantities for baked goods and pastries, it seems wholly unlikely anyone would reach the daily limit for consumption

The Tonkamisu Tart, photograph by Annabelle Davis

In many countries coumarin is controlled, although cinnamon seems to keep getting away with it. Denmark’s beloved cinnamon rolls, kanelsnegle, narrowly escaped a ban in 2013 for containing the maximum amount allowed in food. 

And yet, tonka beans have been banned in the US since 1954. Before this time they were in high demand for flavoring confectionery, chocolate and liqueurs, as well as perfume since the late 19^th C. The fruit of a leguminous tree from the pea family, Dipteryx odorata (odor!), also known as kumaru and Brazilian teak, tonka is native to the forests of Brazil, Colombia, Venezuela and Guyana. Once coumarin was banned in food, it was replaced with vanilla or synthesized coumarin (developed in 1940), but is still legally used in perfume, pipe tobacco and allowed in some alcoholic beverages such as Zubrowka, though it’s unclear why that would be permitted.

Tonka Bean Custard Creas

In Canada where I live, coumarin is not allowed as an ingredient or food additive, but spices and plants containing coumarin are.. Raids aside, Tonka is ,apparently,quite easy to get in the US, despite the FDA ban, though you didn’t hear it here. A pastry chef friend told me she orders it online and that it still appears on restaurant menus. In fact, Alinea’s chef, Grant Achatz, claimed to be ignorant of tonka’s potentially deadly qualities and was ordering it from a spice merchant unwittingly. To be fair, it’s doubtful anyone was consuming anything near a dangerous quantity in Alinea’s sponge cake, especially when one considers the portion sizes on tasting menus! Hopefully this silly and frankly hypocritical ban will one day be overturned. In the meantime, the rest of us non-US residents should consider using tonka more frequently and enjoying it with gusto so that our American friends might live vicariously.

Using Tonka Beans

Photo by Claire Dinhut

I like to use tonka much in the same way I’d use nutmeg, using a microplane to grate it before adding it to recipes. Theoretically you could steep whole beans in a base like cream, but because they are so powerful and one therefore needs so little, I’ve never found myself in a situation where I had a quantity of something I needed a whole bean to flavor. 

You can, however, make a tonka bean infusion akin to vanilla extract. I steeped one small bean in 1 Tbsp vodka, and after a week the liquid was dark brown and powerfully scented. Try subbing it in for vanilla extract for a change. You could use a higher ratio of vodka, but it will take longer to infuse.

Tonka pairs especially well with the ingredients that make up its flavor profile, as well as related ones, such as coffee, almond and stone fruits, in particular apricots and cherries. I never pair it with vanilla, as it would be overkill. Chocolate, on the other hand, takes to tonka beautifully, especially a dark milk (or mixture or milk and dark). If you’re just getting to know tonka, it can be nice to make it the star of the show, letting it shine with a base of dairy, be it butter or cream.

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Tonka Apricot Cream Buns

These tender and sweet yeasted morning rolls are filled with a tonka-scented pastry cream and apricot jam then crowned with a crunchy toasted almond topping perfumed with even more tonka. I drove 4 hours with these in the car on the way to visit family and was nearly driven to total distraction by the mouth-watering scent.

Filling

• 118 g whole milk

• 30 g sugar, divided

• 1/8 tsp grated tonka bean

• 30 g egg yolk

• 8 g cornstarch 

• pinch salt

• 13 g unsalted butter

• 165 g apricot jam

Bun Dough

• 90 g whole milk

• 280 g all-purpose flour

• 38 g sugar

• 4 g instant yeast

• 1/2 tsp kosher salt

• 1/4 tsp grated tonka bean

• 77 g unsalted butter, at room temperature

• 1 egg

• 45 g sour cream

Topping

• 25 g sugar

• 15 g egg white

• pinch grated tonka

• pinch salt

• 65 g sliced almonds

Method

• To make the filling, heat the milk, half the sugar and the tonka in a medium pot over medium heat, just until steaming.

• While the milk heats, in a medium bowl, whisk egg yolk with remaining sugar, cornstarch and salt. When the milk is warm, temper the yolks by pouring it in in a slow, steady stream while whisking. When it’s all incorporated, return to the pot and cook, whisking, until it comes to a thick boil. Continue whisking for about 30 seconds, then remove from heat.

• Strain through a fine mesh sieve into a heatproof bowl to remove any lumpy bits, then whisk in the butter. Place a sheet of plastic wrap directly on the surface, then let cool completely. Refrigerate until ready to use, up to three days.

• To make the dough, heat the milk to just warm, 100-110°F (38-43°C). 

• In the bowl of a stand mixer fitter with the dough hook, combine flour, sugar, yeast, salt and tonka on low. Add warm milk, butter, egg and sour cream; mix on low until incorporated. Increase speed to medium and knead for 10 minutes. (Alternatively knead by hand for 15 to 20 minutes.) The dough should be smooth and bouncy. Transfer to a buttered bowl, cover and let rise in a warm place until doubled in volume, about one hour (or let rise in the fridge overnight).

• Butter an 8-inch square pan and line with parchment paper.

• On a floured surface, pat down the dough and roll into a 10- x 12-inch rectangle. Spread the pastry cream evenly over the surface of the dough, leaving a 1-inch border at one long end. Spread the apricot jam over the pastry cream. Starting at the long end without the border, roll up the dough into a log, pinching the seam to seal. Use a serrated knife to trim the ends then cut the log into 9 equal slices. Place the slices three by three in the prepared pan. Cover with plastic wrap and loosely drape with a tea towel. Allow to rise in a warm place until puffy, about 30 minutes (or 1 hour if dough is cold). Preheat oven to 175°C/350°F.

• To make the topping, in a medium bowl, whisk together sugar, egg white, salt and tonka until combined. Fold in sliced almonds.

• When the buns have risen, distribute topping evenly overtop. Bake for 35-40 minutes, until golden and an instant read thermometer inserted into the middle reads 98°C/210°F. Allow to cool slightly on a wire rack before serving. 

  

• These are best eaten within a few hours of being made, but can be reheated in a 150°C/300°F oven to revive the next day.