The walnut is said to have originated when Dionysus, the Greek god of fertility and wine, fell in love with Carya, the youngest of three daughters. When Carya died, Dionysus was heartbroken. He immortalized her, turning his object of desire into a walnut tree.
Walnuts are one of those ancient foods that come up in classical mythology, in the Quran and the Bible. The small round nut appears in modern literature time and again: as a symbol of Jean-Jacques Rousseau’s idyllic childhood, or a sign of romantic love in Goethe’s first novel, The Sorrows of Young Werther.
Matthieu Kohlmeyer knows the charms of the walnut well. He is the CEO and General Manager of La Tourangelle, which produces artisanal nut oils in California’s Sacramento Valley. The French-Californian company was born in 2002, when Kohlmeyer arrived in the Bay Area, a fresh-minted MBA, armed with cast-iron roasters, extractors and a business plan. Kohlmeyer would introduce Americans to high-quality nut oil, a specialty of central and southwestern France, using one of California’s most plentiful crops: the walnut. The state supplies 99 percent of U.S. commercial walnuts and the bulk of what’s sold in markets around the world. Until Kohlmeyer, most California walnut oils were heavy and watered-down — better left to traditional applications like painting or joinery. Kohlmeyer was on a mission to change that, proving that sometimes it’s a newcomer who makes the most of what’s local.
In Saumur, an old town near the Loire River, about a three-hour drive from Paris, Kohlmeyer’s family operates a 150-year-old mill.
“I grew up in Paris, but my mother comes from Angers in the Loire Valley,” Kohlmeyer told me. “Every other weekend we traveled there to be with my grandparents,” he said, describing his farm-to- table childhood. “They made their own wine, ate their own produce, and raised rabbits and chickens. It was there that I discovered the taste of good food and a connection to the land.”
Near his grandparents’ home, a few miles up the Loire, Kohlmeyer’s German-born father had stumbled on a traditional nut oil mill, a local fixture since the 19th century. He joined the tiny business, became a partner, and eventually took over management. Matthieu would soon be working alongside him in marketing and sales, expanding the company, Huilerie Croix Verte.
Walnuts are one of France’s oldest and most beloved foods, and in nearly 200 years, the oil production process hadn’t changed much. Each fall, the nuts are harvested, sun- dried, shelled by hand, usually roasted and pressed into a rich, flavorful oil. By October, markets are brimming with walnuts, and in rural regions where the trees blanket the ground, farmers sell sacks right out of their barns, along with bottles of the topaz-colored oil. In France, the walnut is the nut; the translation of “walnut” is simply noix, or “nut.”
Though the walnut has a storied place in the popular imagination, that didn’t stop the Kohlmeyers from breaking with French tradition. Looking to grow overseas, the family exported 23-year-old Matthieu instead of their oils, since exposure to light and heat compromises quality. “I spent close to six months getting the oil mill construction started,” recalls Kohlmeyer of his early days in California, which were marked by logistical hurdles. “The next challenge was securing a building permit to set up a nut oil mill with equipment from France.” By June 2003, Kohlmeyer had created his first batch of California walnut oil. “But that was only the start of the real work,” he insists, “which was getting the word out.”
Hardly a staple in U.S. kitchens, Kohlmeyer’s walnut oil was still a long way from supermarket shelves. But his timing couldn’t have been better; Kohlmeyer arrived in California when researchers first touted the cholesterol-lowering properties of the walnut, the virtues of its omega-3s fatty acids and antioxidants, and just as locavores were reaching for domestically-produced bottles. In the meantime, EVOO was falling from grace; Tom Mueller’s 2007 expose in The New Yorker, which launched a series of investigations, revealed that more than two-thirds of imported olive oil for sale in the U.S. is fraudulent, doctored with lesser ingredients like soybean oil. For Kohlmeyer, the conditions were ripe for success. In the age of Ottolenghi, when home cooks are eager to branch out beyond the usual extra virgin olive, walnut oil has acquired a devoted following. Each month, more than 15,000 bottles of La Tourangelle’s walnut oil are sold in markets across the U.S.
Like in France, California’s 4,000 walnut growers are mostly family-owned operations. A walnut tree can produce nuts for 75 years to a century; most orchards are passed down from one generation to the next. La Tourangelle is yet another story of food and wine immigration from France to California. Similarities in climate and soil connect the two regions, but Kohlmeyer notes that California walnut varieties differ from their French counterparts. “The flavor of the oil we first produced was lighter,” than what his family makes in France, he explains, “and this turned out to be a good thing. Because for new customers discovering roasted walnut oil, the lighter flavor was usually preferred.”
Kohlmeyer’s favorite walnuts reside in a century-old grove on California’s Central Coast. But he also raves about varieties and flavors he has sampled in Moldova and Uzbekistan. The walnut guides his travels around the world to meet artisanal oil makers large and small. It seems not even California’s epic drought can stop him. “The crop size was the largest ever this year,” he says, “and is expected to be even larger next year.”
Walnut oil is not for cooking; heat ruins the flavor. It’s best in salads, swirled into soups, tossed with pasta or used to finish meats and fish. It’s delicious brushed on squash before roasting, drizzled onto Greek yogurt, and baked into cakes and banana breads. Refrigerate after opening and use within 6 months.