Tasting maple syrup, for science

Forget about buckets. Most maple syrup is now made with an assortment of machines and tubes so complex that some sugarmakers call their final product “technosyrup.” Chat with a few of them, boiling sap one evening, and you’re likely to hear debate about reverse osmosis sap extractors, “steam-away” units and air injectors. They’ll all agree that today’s maple syrup is produced more quickly than it was a generation ago, and many will argue that the new devices produce a syrup finer in quality — that’s just as pungently delicious as ever.

But is it?

Tim Perkins, director of UVM’s Proctor Maple Research Center in Underhill Center, has decided to find out. This week, he and his staff will start boiling sap at a new research building to test exactly what effect new technologies have on the chemistry, flavor and quality of maple syrup.

“This is the only such facility in the world,” Perkins says. “Nobody since the 1940s has done these kinds of experiments, and the industry has changed a lot since then.”

Pointing to two gleaming evaporators that look like undersized subway cars, Mark Isselhardt ’98, one of Perkins’s maple technicians, explains the method: “The only way to find out what’s going on is to run side-by-side tests.” Above his head, on a loft, a large stainless steel trough waits for the season’s first sap run.

“Each evaporator will be fed from this one source,” he says, looking up, and then traces a line through the air showing where the sweet water will flow through glass dairy pipes into the 10-foot-long machines. Inside, the sap will boil down, monitored by probes that will measure temperature at six points.

“The two evaporators are identical except that one will have an air kit and one won’t,” says Isselhardt. Air injectors are intended to produce a lighter, finer-grade syrup — long the goal of skilled syrup makers. But how does this additional air — bubbled into the hot sap to lower the boiling temperature — affect the final product? Collecting data on the path from tree to mouth will give Perkins and his team a detailed portrait of each batch of syrup. Controlling the variables along the way will allow them to discover whether glowing anecdotes about these injectors are supported by hard-nosed science.

Tasting and smelling the product

And maple syrup science really is a nose — and mouth — science. The technical term is organoleptic. “Which means you put it in your mouth and taste it,” says Perkins, smiling. “We get people who know the flavor of maple syrup, and off-flavors, and they try each one.” Laboratory tests using gas chromatography provide a breakdown of the many compounds in the syrup, which supplements the tastebud approach. “These air injectors appear to make the syrup lighter,” Perkins says. “The real question is: how do they impact the flavor?”

Maple syrup is a natural product, but it is not simple. The interplay of seasonal tree biology, boiling temperature, microorganisms, sugar chemistry, storage time, final container — and a long list of other subtleties — makes each glinting amber-to-chocolate bottle nearly as distinct as varieties of wine. “Syrup is not just concentrated sap,” Perkins says, describing how the sugar in the water is broken from sucrose into glucose and fructose, darkened by bacteria, and carmelized by heat.

This new facility will allow Perkins and other researchers to conduct experiments on up to four evaporators simultaneously. With funding from the USDA, his research over the next two years will focus on air injectors with raw sap. “Then we’ll move on to air injectors with reverse osmosis systems,” he says. “Eventually we’ll build up a body of knowledge about how various mixes of equipment affect the quality and chemistry of maple syrup.”

A history of maple research

Maple research began at UVM in the 1890s, and the Proctor Maple Research Center was established in 1946 with the donation of an old hill farm to UVM by Governor Mortimer Proctor. It’s one of three maple research stations in the world, along with Cornell’s and the Centre Acer in Quebec. The Proctor Center’s main laboratory was established in 1988 and expanded in 1994, and has received ongoing support from Senators Leahy and Jeffords.

The new cedar-shingled shed — “its not a sugarhouse,” Isselhardt says, “it’s a research processing facility” — is directly across the dirt driveway from the lab. With a price tag of about $100,000, it was built with funds from the Proctor Center’s endowment fund, established by UVM in 1999, and contributions from individuals, maple-related companies, and several maple associations, including the Vermont Maple Sugar Makers’ Association, the North American Maple Syrup Council, and the Chittenden County Maple Sugarmakers’ Association.

“We work with all sorts of people in the maple industry,” Perkins says, “and listen to their concerns and questions.” Including some head-scratching about strange changes in the marketplace. “For years, the art of sugarmaking has been to make syrup lighter and lighter. But there is a growing disjunct between the consumer world and the producers,” Perkins says with a sigh. “Many people now prefer the dark, strong tasting syrups, while the sugarmakers keep after the fancy grade.”

By providing objective data about the chemistry of maple syrup, Perkins expects this new research facility will help producers make sense of new tools and new tastes in an old art.