Hazelnut

• 1. Introduction

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  The hazelnut is the fruit of the hazel tree, a nut so ancient and so woven into human life that traces of it survive in mystical poetry, fairy tales, and the archaeological record alike. In 1995, researchers uncovered a midden pit on the island of Colonsay in Scotland filled with hundreds of thousands of burned hazelnut shells, the remnants of a single year's harvest carried out perhaps nine thousand years ago. That discovery raised an immediate question: who were these people, why did they gather here, and what does a pit full of charred shells tell us about how early communities organized themselves? The answers reach further than anyone expected. From the shores of a Scottish island to the hazelnut orchards of the Willamette Valley in Oregon, from Turin's chocolate workshops to the pages of William Shakespeare, the hazelnut has traveled an extraordinary distance. How it got there, and why it remains central to so much of what we eat, drink, and imagine, is a story that begins long before anyone thought to write it down.

• 2. The Colonsay Discovery

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  Colonsay is a small island off the west coast of Scotland, and in 1995 it yielded one of the most striking finds in the archaeology of prehistoric diet. A large, shallow pit was excavated there, packed with the burned remains of hundreds of thousands of hazelnut shells. Radiocarbon dating placed the nuts at 7720 plus or minus 110 years before present, which calibrates to around 6000 BCE. Similar hazelnut deposits are known from other Mesolithic sites in Britain, but the sheer concentration at Colonsay has no real parallel; comparable sites exist only at Farnham in Surrey and Cass ny Hawin on the Isle of Man.

  Pollen analysis added a striking detail to the picture. Every hazel tree appears to have been felled at the same time, and the harvest itself took place within a single year. The pit originally sat on a beach near the shore, and nearby it lay a hearth, two smaller stone-lined pits of unknown purpose, and a second cluster of pits. The scale of the operation, combined with the relative scarcity of large game on the island, has led researchers to suggest that Colonsay may have supported a community living largely on plant-based foods during their stay.

  What the Colonsay pit reveals, above all, is the capacity for planning. Gathering nuts in that volume, across an entire island's hazel population, in a single season, required coordinated effort. Hazelnuts do not keep themselves; they had to be processed, stored, and presumably dried or roasted, all of which the burned shells suggest. The nuts that fed that community were harvested roughly seven to eight months after the trees had been pollinated, the same interval the hazel tree requires today.

• 3. The Fruit Itself

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  Corylus avellana is the species most associated with the commercial hazelnut, though the name covers any nut from the genus Corylus. Two forms are commonly recognized: the cob and the filbert. A cob is roughly spherical to oval, while a filbert is more elongated, being about twice as long as its diameter. Both sit inside a fibrous outer husk and, when ripe, fall free of it entirely.

  The ratio of nut to fruit varies by cultivar, running from 33.2% to 49.5%. Cultivars grown close to the Mediterranean Sea tend to show the highest nut-to-fruit ratio of all. The thin, dark brown skin covering the seed is sometimes removed before cooking; otherwise, the seed is eaten raw, roasted, or ground into a paste.

  The list of named cultivars is long: 'Barcelona', 'Ennis', 'Tonda Gentile', 'Tonda di Giffoni', 'Tonda Romana', 'Kent Cob', 'Halls Giant', and 'Willamette' are among them, alongside more than a dozen others. Some are bred for large nut size or particular fruiting windows; others serve purely as pollinators. Many commercial hazelnuts are propagated from root sprouts, and some cultivars trace their origins to crosses between common hazel and filbert.

• 4. Growing and Harvesting

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  Brutting is the traditional technique for coaxing more nuts from a hazel tree. At the end of the growing season, growers snap - but do not fully break off - the tips of new shoots, about six or seven leaf groups from the point where each shoot joins the trunk or branch. The stress redirects the tree's energy toward flower bud production, and therefore toward fruit. An area of cultivated hazelnuts has its own traditional name: a plat.

  In Europe, hazelnuts are commonly grown as multi-trunk trees where the rootstock is formed by the variety itself. A single-trunk form can also be created by grafting a scion of the desired variety onto a Corylus colurna rootstock, which reduces suckering and makes mechanical harvesting more practical.

  Harvest falls in mid-autumn each year. Most commercial growers wait for the nuts to fall naturally rather than shaking them from the tree. Four pieces of machinery handle the process: the sweeper, which consolidates fallen nuts into the center of the row using a 2-meter belt and a rear blower capable of air speeds up to 90 meters per second; the harvester, which lifts material and separates nuts from leaves, empty husks, and twigs using a rotating cylinder fitted with hundreds of tines; the nut cart, which collects the separated nuts; and the forklift, which shuttles filled totes to waiting processors. Orchards may be harvested up to three times in a single season, depending on how many nuts remain in the trees and the pace of natural drop.

  In the Willamette Valley of Oregon, where United States production is concentrated almost entirely, growers choose between two timing strategies. The first is an early pass when roughly half the nuts have fallen, allowing the harvester to work faster with less material on the ground. The second is a single pass once all the nuts are down. Growers who prefer the early approach accept that two or three passes take more total time, but consider it the better method overall.

• 5. Turkey, Italy, and Oregon

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  In 2023, world hazelnut production reached 1.13 million tonnes. Turkey led by a wide margin, accounting for 57.7% of global output. Italy and the United States ranked as the other major producers. The United States contribution comes almost entirely from Oregon's Willamette Valley, a geography that shapes both the economy and the cultivar choices of growers there.

  In Ireland and the United Kingdom, the nut carries a specific local identity under the name cobnut. The main cultivated variety is the Kentish cobnut, grown in plats, hand-picked, and often eaten green rather than dried. A national collection of cobnut varieties is held at Roughway Farm, near Plaxtol in Kent, according to the BBC. The name itself has a small and unexpected history: cob was an old word for head or noggin, and children once played a game in which they tied a string to a hazelnut and used it to strike an opponent on the head.

• 6. Chocolate, Kitchens, and Cuisine

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  Turin, in northern Italy, is where the combination of ground hazelnuts and chocolate first took a distinctive culinary form. That mixture is called gianduja. With finer pulverization of the hazelnuts, gianduja developed further into gianduiotto and, later, into Nutella, now among the most recognized hazelnut cocoa spreads in the world. Hazelnuts also appear in chocolate truffles and in praline, a confection for which they are a standard ingredient.

  Austrian baking uses hazelnut paste as an ingredient in tortes, the Viennese hazelnut torte being one example. Kyiv cake uses hazelnut flour to flavor its meringue body and crushed hazelnuts over its sides. The French dessert dacquoise often contains a layer of hazelnut meringue. In Georgian cuisine, hazelnuts appear alongside walnuts in the sauce satsivi and in the snack churchkhela. Turkish cuisine also makes significant use of them. Muesli, eaten across northern Europe as a breakfast food, counts hazelnuts as a regular component.

  The oils pressed from hazelnuts are strongly flavored and high in monounsaturated fat, primarily as oleic acid, which makes up 75% of the total fat. Linoleic acid, a polyunsaturated fat, accounts for 13%, and saturated fats - mainly palmitic and stearic acid together - for around 7%. Hazelnut oil is used in cooking and as a dressing for salads and vegetables. The nut also lends flavor to Frangelico, an Italian liqueur.

  A 100-gram serving of raw hazelnuts supplies 628 kilocalories. The macronutrient split runs 61% fat, 17% carbohydrates, and 15% protein, with 5% water. Vitamin E, thiamin, folate, manganese, magnesium, and dietary fiber all exceed 20% of the daily value in that same serving. Niacin, pantothenic acid, vitamin K, zinc, and potassium fall in the moderate range of 10 to 19%.

• 7. Hazelnuts in Literature

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  Julian of Norwich, the English mystic who lived from around 1343 to after 1416, drew on the hazelnut as a literary device in her Revelations of Divine Love. For Julian, the smallness of the nut became a way of thinking about the fragility and contingency of all created things.

  William Shakespeare gave the hazelnut a different role entirely. In Romeo and Juliet, the shell of a hazelnut serves as the chariot of Queen Mab, the fairy who delivers dreams to sleeping humans. The choice of a hazelnut shell - small, hard, perfectly enclosed - carries a playful logic for a vehicle small enough to carry an invisible passenger.

  The English Romantic poet John Keats used hazel fruit as a metaphorical device in his ode To Autumn, a poem preoccupied with ripeness, abundance, and the slow turning of the season. All three writers chose the hazelnut not for its flavor or its calories but for what it stands for: smallness, completeness, something ordinary that holds more inside it than it appears.