University of Vermont

Vermont Quarterly

Of Cheese & Rocks & Time

Inside the cheese caves at Jasper Hill Farm.

On the trail of a mystery crystal

Photos and Story by Joshua Brown

struvite crystals from Paul Kindstedt's laboratoryIn 1962, at the bottom of the Ika Fjord on the southwest coast of Greenland, a Danish geologist found spectacular columns of rock growing, like white and algae-covered tree trunks, up to sixty feet tall. It was the first discovery of the mineral ikaite, a strange, watery form of calcium carbonate. Later, geologists would find ikaite in the Arctic Ocean, in sea-bottom sediments in Antarctica, and other freezing places. Taken out of the cold deep water, ikaite can melt rapidly, its aqueous crystals dried into chalk.

Now, walk into City Market in Burlington, or Murray’s Cheese Shop on Bleecker Street in Manhattan, and head toward the cheese counter. Ask the cheesemonger for one of their best washed-rind cheeses. If you’re lucky, they’ll have a small wheel called Winnimere. It’s only made in winter, out of raw milk from the Ayrshire cows at the Jasper Hill Farm in Greensboro, Vermont—and it’s aged at a bit over fifty degrees Fahrenheit for two months. When you get home, open the blue-labeled wrapper: it’s going to be beautifully stinky. Note the salmon-colored top surface, overlaid with white fuzz. Scrubbed with a salt brine as it ages, this rind holds a complex layer of bacteria and yeast that imparts to the oozy inner cheese an amazing complexity of flavors, like bacon mixed with sweetened cream.

If you happen to get a bit of this orange rind on your spoonful of soft inner cheese—or you’re one of those eat-it-all types who enjoy the meaty texture of a rind—pay close attention. Notice a slight crunchiness when you bite down? Or a kind of after-effect, like a pleasant toothpaste grittiness on your teeth? Those are cheese crystals. And many of those cheese crystals—a team of UVM scientists has discovered—are cold-water ikaite.

“It shouldn’t be there,” says renowned UVM mineralogist John Hughes. “But it is.”

“This was very surprising,” says Gil Tansman, who completed his doctorate in food science at UVM this spring and led the discovery. 

In Europe, people have been making washed-rind cheeses since at least the Middle Ages and the first scientific explorations of crystals in cheese began more than a hundred years ago. But very little is understood about the crystal phases of cheese and other foods. And which crystals contribute to the noticeable grittiness of many washed-rind cheeses had never been known—until Tansman thought “minerals are rocks,” and marched across campus to speak with Hughes, professor of geology and past UVM provost. Together with Paul Kindstedt, a professor of nutrition and food science, they launched some of the first-ever explorations of crystals in food with advanced X-ray techniques.

“We’re discovering rare crystals that, it turns out, people have been eating for centuries,” says Tansman, who submitted the team’s findings about cheese—to the geology journal Canadian Mineralogist.

Ikaite is unstable at room temperature. “So how in the world is it forming and staying on cheese?” says Kindstedt. At first, when Tansman and Hughes removed these crystals from the rind, they “turned to mush,” Hughes says, before they could finish studying them under the X-ray beam in the university’s single-crystal diffractometer. Only after the scientists learned to quickly coat the crystals in glue could they collect data.

Something is happening on the surface of the washed-rind cheese that neither food scientists nor geologists yet understand. “And that’s what makes this exciting,” says Kindstedt. In this complex smear, ecosystems of microbes and yeasts draw proteins and mineral elements, including magnesium and potassium, from within the aging curds below and carbon dioxide and ammonia from the air above the cheese, the near-magical “headspace.” This microscopic lawn creates a mysterious environment that allows these unexpected crystals to nucleate and grow large enough that you might feel them on your tongue.

One morning this spring, Kindstedt and one of his new graduate students, Pat Polowsky, are working in the Carrigan Wing of Marsh Life Science Building, looking at short videos they made with a geological microscope. Against a purple background, spear-tipped, rainbow-edged crystals of ikaite and more-blunt crystals of the bacteria-loving mineral struvite appear and disappear as they rotate under polarized light, confirming their genuine identity as crystals, and “not just cheese gunk,” says Polowsky. 

The scientists’ goal is to take the definitive results from their X-ray studies and use them to corroborate lower-cost microscope techniques that could give cheesemakers a tool to ID crystals in their own products. They’re also launching an effort to collect washed-rind cheeses from cheesemakers around the country. “There may be other really interesting crystals that we haven’t seen yet,” Kindstedt says.

Since arriving at UVM in 1986, Kindstedt has been a leading figure in the development of a scientific understanding of cheese. He started his career helping industrial-scale cheesemakers improve the stretch in mozzarella, and spent years finding methods to prevent calcium lactate crystals from forming in cheddar, since many consumers misinterpret surface crystals as unwanted mold. He’d always enjoyed the pop and crunch of crystals in a nicely aged parmigiano-reggiano, an old gouda, or a three-year-old cheddar.

But in Sicily, in 2012, Kindstedt had “an epiphany over my double-espresso,” he says. Meeting with traditional cheesemakers from Europe, he realized that crystals were not just an incidental aspect of some older hard cheeses, but were “deep signs of authenticity” in many styles of cheese, he says—and that “the crystal reveals the conditions that are making the cheese.” In white-mold cheeses, like brie and Camembert, there’d been research, particularly in France, to understand the softening process, how they ripen from too-firm, to perfectly oozy, to an unpalatable liquid.  “It’s driven by crystals that form at the surface,” he says. However, no one had taken a hard look at crystals in the washed-rind cheeses, a very profitable category of artisanal cheese. And crystals of any kind were hardly studied in the U.S. cheese industry, except as a problem to be eliminated. Having just completed his sweeping history, Cheese and Culture, Kindstedt reoriented his research program to seek a deeper understanding of crystals.


Paul  Kindstedt and his  students, Gil Tansman and Pat Polowsky,outside at Jasper Hill Farm.From cows to caves at Jasper Hill Farm, professor Paul Kindstedt and his students, Gil Tansman and Pat Polowsky, are collaborating with the cheesemakers—seeking a deeper understanding of the taste and origins of crystals.

/>Under a steel-gray March sky, awaiting the arrival of a spring blizzard, Paul Kindstedt, Pat Polowsky, Gil Tansman, and I drive down the driveway at Jasper Hill Farm, past a deep-space-blue barn painted with flying cows and a giant moon of cheese. Soon we are in one of their custom-built caves—The Cellars at Jasper Hill, seven arching concrete vaults blasted into this Greensboro hillside—filled with thousands of ivory and orange and gorgeously mold-and-microbe-encrusted wheels and blocks of cheese. 

Mateo Kehler—one of the co-owners of Jasper Hill with his brother Andy Kehler, UVM Class of 1993—is standing beneath a towering wooden rack of cloth-wrapped cheddar, talking passionately with the visiting scientists about crystals. While the slight crunch of a fine cheddar has been appreciated by cheese-lovers for a very long time, the sensory characteristic called grittiness is a complex issue. And tastes change. Cheese crystals in some markets are getting to be hot. “Cheesemongers, that are cutting at the counters, yes, they’re getting questions about crystals and they’re asking us,” Kehler says.

“Maybe ten years ago,” Kehler says, if consumers tasted cheese crystals, “they would’ve freaked out about sand or said ‘something’s wrong with my cheese.’ And it’s still considered a defect in cheddar land. But, for us, these are attributes that we can leverage. Crystals can be part of the story, and they’re generally associated with really delicious cheese.”

But balance is all. “Sometimes crystals are desirable and sometimes they’re not,” says Kindstedt. “There can be too much of a good thing.” Which is why he and Polowsky are collaborating with staff at Jasper Hill as they develop a new research effort to establish the relationship between grittiness—the complex sensation of crystals in the mouth—and the types and sizes of crystals that grow in washed-rind cheeses. It ties in with the scientists’ belief that identifying crystals may reveal the peculiar conditions that gave rise to them. “If we know the magic conditions, maybe we can modulate the magic,” says Kindstedt, opening possibilities of controlling crystal growth for more-delicious cheese.

But the discovery of ikaite on washed-rind cheese opens bizarre possibilities far beyond the marketplace, the UVM scientists think. It may give a view back 3.7 billion years, to the beginnings of life. Ancient seawater mats of microbes are believed to have produced ikaite and other forms of calcium carbonate, depositing them on the bottom of oceans. Geologists conjecture that calcium carbonate structures, called stromatolites, hold the entombed remnants of these microbes, and are evidence of the planet’s earliest life-forms. But this idea is controversial, and—as the UVM study shows—the conditions that cause ikaite to crystallize are far from fully understood. Which is where cheese could help. “The environment on the surface of a washed-rind cheese in some ways mimics this geologic environment, this ancient algal mat,” says John Hughes. The team’s new research shows that the microbial smear on washed-rind cheese can induce the crystallization of ikaite as well as the minerals brushite and calcite—suggesting that it could work as a model system to better understand how ancient microbes may have formed stromatolites, as well as other far-reaching questions about ancient climates. “We’d like to take what’s happening in the cheese ripening room and use it to infer things that happen out in nature,” says Kindstedt.

We’ve left the cheddar room at Jasper Hill and moved into the cool, humid vault that holds ripening washed-rind cheeses. Here, hundreds of wheels of Winnimere, the 2013 winner of the American Cheese Society’s “Best in Show” award, sit on gleaming steel racks. It’s similar to some cow’s milk cheeses from the mountains of Switzerland and France, like Vacherin Mont d’Or or Försterkäse. Simliar, but not identical, since Winnimere is made by wrapping a piece of spruce bark, a thin strip of the cambium taken from a forest of Greensboro, around each wheel. (When I hand my wife a piece of this cheese that evening, she says, “It’s like eating the North Woods.”)

I’m thinking about how delicious it would taste with a glass of Everett, a great porter beer from down the road at Greensboro’s famed Hill Farmstead Brewery. My thoughts turn, somewhat more loftily, to philosopher Alfred North Whitehead’s notion of the “fallacy of misplaced concreteness.”  Sometimes the benefits of interdisciplinary research are presented as if scientists had to reach across from the concrete realities of their disciplines—geology, food science, microbiology—and create an imaginary connection to the other. But nature’s going to do what it will, making microbes that evolve and gene-swap in our grocery bag, crystals that care not one whit about the boundary between biology and mineralogy, rocks that become food. Maybe it’s just the thought of beer, or the pungent subterranean air going to my head, but I like to imagine this Northeast Kingdom cheese can summon a trace of crystalline flavor from the bottom of an icy ocean, even the beginning of life itself.

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