Fresh chestnuts Photo by Christine Burns Rudalevige

My family spent the last months of 2011 in Lyon, France. As my husband lectured at the Institut d’Études Politiques de Lyon to finance our rented, centuries-old digs in the magical old part of the city, I attempted to home-school my then fifth- and eighth-grade kids. Our mornings were filled with American history exploration and science projects. In the afternoons, we ventured out to the holiday markets for French language practice and retail mental math in euros.

On most days, we’d stop at a stall selling marron chaud, freshly roasted chestnuts presented to us in paper cones, a healthy snack that also warmed our hands. When my daughter asked if we could eat more chestnuts at home, I likely replied an off-hand “Sure!” But I’ve since realized that to get to the right answer to that question, we had to go back to both American history lessons and more science projects.

American chestnut trees (Castanea dentata) used to grow in the eastern woodlands from Maine to Alabama and as far west as Kentucky and Ohio. There were billions of the trees, some measuring more than 100 feet tall and four to five feet in diameter. The burrs, the round spiky balls that contain the nuts, fell to the ground in autumn and were wildly popular ingredients for both Native Americans and American colonists. Throughout the 1800s, train car loads full of chestnuts were brought to Baltimore, Boston, Philadelphia and New York to be sold, freshly roasted, from street vendors like the ones we’d come to know in Lyon. But then a fungal blight brought in with a shipment of ornamental Japanese chestnut trees at the turn of the 20th century led to Castanea dentata’s near extinction.

The nonprofit American Chestnut Foundation has been working to develop a blight-resistant American chestnut varietal by crossing American chestnuts with Chinese ones, treating affected trees and making genetic modifications. The last is turning out to be the most reliable prospect for restoring the tree to its native habitats.

Last month, the USDA released a positive preliminary report on a genetic modification that could make future chestnut trees resistant to the blight that killed their ancestors. Spearheaded by scientists at the SUNY College of Environmental Science and Forestry in New York and supported locally by researchers at the University of New England and the Maine chapter of the American Chestnut Foundation, this modification inserts an extra gene into American chestnut DNA. The gene comes from wheat, UNE professor Thomas Klak explained, but many other wild and cultivated food plants like strawberries, bananas, chocolate and barley have it, too.

“The inserted gene contains an enzyme called Oxalate Oxidase (OxO) … that detoxifies but does not kill the fungal blight’s otherwise deadly oxalic acid while emitting two off gases (hydrogen peroxide and carbon dioxide) in tiny quantities,” Klak said.


He manages a USDA-permitted orchard in Biddeford of more than 600 trees, most of which are American Chestnuts with the OxO gene. Other trees in the orchard have varying percentages of Chinese chestnut genes. Photos clearly show that the genetically modified trees, called the Darling 58 American Chestnut, are healthier.

While the USDA is accepting comments on its draft report on the OxO genetic modification until December 27, the agency seems to be leaning toward approval, Klak Said. The key findings of the report say:

a) OxO is widely understood to have no known safety concerns when consumed by humans or livestock.

b) Darling 58 and non-transgenic nuts are almost identical nutritionally.

c) Based on 15 years of research, Darling 58 trees are unlikely to harbor or transmit plant pathogens or pests that might be harmful to native plants, soil composition or agricultural products.

d) It’s difficult to predict the impact of Darling 58 American chestnuts on forest biodiversity because the overall ecosystem has changed since American chestnuts disappeared from the landscape. But the report says it is reasonable to believe its long term impacts on the biodiversity of animals and micro-organisms living among the modified trees will be positive.


e) Darling 58 American chestnuts may provide rapid sequestration of carbon from the atmosphere.

Final approval of the genetic modification will allow the pollen from the trees in Klak’s regulated orchard to be used to help set burrs on hundreds of native trees that chestnut tree preservationists have been fostering around Maine since the summer of 2020. This pollination could happen as soon as next summer.

All of these fostered native American chestnuts will eventually die of blight, Klak said. “But breeding them with the blight-tolerant pollen creates a new generation of wild genetic diversity and blight tolerance. That’s the scientifically-based bright future for American chestnut restoration in Maine,” Klak said.

Great news! But what I want to know is, when will I be able to eat chestnuts from the trees?

Freshly roasted chestnuts Photo by Christine Burns Rudalevige

By the time I was born, American chestnuts had mostly disappeared. I have no frame of reference for how the taste of our Lyonnaise marron chaud would compare to native nuts. But food historians and Klak say the $20 million worth of whole chestnuts now imported mostly from China and Italy into the United States to be roasted on open fires at Christmastime are larger, starchier, and less flavorful than those that fell from native trees.

Ninety percent of the 115 American chestnuts trees UMaine Professor Emeritus Bucky Owen has managed for three years on the Orono Land Trust have survived, and some are now 14 feet tall. Only four trees produced male pollen and one had female flowers this year, Owen reported. Typically, it takes five to 10 years for a chestnut tree to flower and produce nuts reliably. Nuts that result from being dusted with Darling 58 pollen will largely be used to seed the chestnut tree population. So it may be 15-20 years before we’ll be able to score a local chestnut to roast over an open fire. I’m hopeful it’ll be well worth the wait.


That said, Klak has supplied Jon Denton at Sweet Cream Dairy on Maine Street in Biddeford with chestnuts from the relatively few remaining wild nut–producing trees in the state. If you hightail it there, you might be lucky enough to score a pint or two. I suggest making this cake using imported chestnuts to go with it.

To decorate your cake like this Chestnut Chocolate one, lay a doily atop the cake and sprinkle it with confectioners’ sugar. Carefully lift off the doily. Photo by Christine Burns Rudalevige

Chestnut Chocolate Cake

If you don’t want to bother to roast and peel the chestnuts, you can buy jars of cooked and peeled Italian chestnuts at either Micucci’s Grocery Store or Monte’s Fine Foods in Portland. Serve with Sweet Cream Dairy’s chestnut ice cream or whipped cream.

Makes one (9-inch) cake

1 pound whole, raw chestnuts
1 ½ cups heavy cream
1/2 cup sugar
1/4 teaspoon salt
1 whole vanilla bean
10 tablespoons unsalted butter, plus more for greasing the pan
4 ounces very dark chocolate (at least 72 percent cacao), chopped
4 eggs, separated
1/8 teaspoon cream of tartar
Confectioners’ sugar, to garnish

Preheat the oven to 425 degrees F.


Use a sharp knife to score a ¾-inch X on the top of each chestnut. Scatter the nuts, cut side up, on a baking sheet. Slide the sheet into the oven and bake until the cut edges of the skins start to peel away from the soft center, 20-22 minutes.

Remove the nuts from the oven. Reduce the heat to 350 degrees F. When the nuts are cool enough to handle, peel both the outer shell and the inner skin from the nuts. You should have about 1/2 pound (1 cup) peeled, roasted chestnuts.

Combine them with the cream, sugar and salt in a small saucepan. Use a knife to split the vanilla bean lengthwise and scrape out its seeds. Toss both the seeds and the pod into the pan. Place the pan over medium heat and simmer the mixture until the chestnuts are very soft, 10-12 minutes. Remove the vanilla bean pod and puree the rest of the mixture into a smooth paste. You should have about 2 cups of puree.

Grease a 9-inch round cake pan and line it with parchment paper.

Melt the butter with the chocolate in a medium saucepan over low heat. Once the butter melts, use a whisk to combine the two ingredients into a smooth sauce, then take the pan off the heat. Add the chestnut puree to the pan and whisk to fully incorporate it. Add 1 egg yolk at a time, whisking after each addition.

Combine the egg whites and the cream of tartar in a metal bowl and use an electric mixer to beat the whites to stiff peaks. Gently stir one-third of the beaten egg whites into the chocolate-chestnut mixture to lighten up the batter. Fold in the remaining egg whites.

Transfer the batter to the prepared pan. Bake until the center of the cake is just set, 22-24 minutes. Cool the cake on a wire rack to room temperature. Flip the cake onto a plate and sprinkle with confectioners sugar.

Local foods advocate Christine Burns Rudalevige is the editor of Edible Maine magazine and the author of “Green Plate Special,” both a column about eating sustainably in the Portland Press Herald and the name of her 2017 cookbook. She can be contacted at:

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