Chestnut

Chestnut flour (farina di castagne) has been a dietary staple in Corsica, parts of Italy, and the Balkans for centuries. Made from dried and ground chestnuts (usually the less sweet "Brown" or "Common" varieties rather than the prized Marroni), it is naturally gluten-free and was historically used as a wheat substitute when grain was scarce. The flour behaves quite differently from wheat flour: it contains high amounts of starch and natural sugars that brown quickly and can turn bitter if overheated. In Corsica and the Garfagnana region of Tuscany, it is still used to make castagnaccio, a dense, rustic flatbread traditionally dressed with olive oil, rosemary, and sometimes walnuts. Chestnut flour must be stored in a cool, dry place or refrigerated; the natural sugars make it prone to mold and insect damage faster than wheat flour.

Before 1900, the American chestnut (Castanea dentata) was one of the most important trees in Eastern U.S. forests, comprising up to 25% of hardwoods from Maine to Georgia. The species was functionally wiped out within 50 years by the chestnut blight fungus (Cryphonectria parasitica), which arrived on imported Japanese chestnuts. The loss reshaped entire ecosystems and rural economies—chestnut lumber, fence posts, and mast (the nuts) were invaluable. Unlike European and Asian species, American chestnuts had no natural resistance. Modern efforts combine hybridization with Chinese chestnuts (which carry blight resistance) and genetic modification to reintroduce the species. American chestnuts, when found, tend to be smaller but intensely sweet.