This time of year, Something Wild co-host Dave Anderson is busy in his sugar house. He’s trying to keep the sap boiling just as fast as it flows through the network of blue tubing that runs through his sugarbush. He even sets a timer to remind himself to keep feeding wood into the fire under the evaporator.
It’s a charming setting, with sweet-scented maple steam wafting out the vents and drifting down into the village.
“This is the beginning of the season, so we're all high hopes and optimistic,” says Anderson of the Forest Society. “We think it's going to be amazing. Nothing has diminished our enthusiasm. We're not weary and sleep deprived yet.”
“This visit to a sugar house was actually my first time seeing how maple syrup gets made,” says Something Wild co-host Chris Martin of NH Audubon. “And I was especially curious about the raw material, the sap, before it becomes syrup.”
“It’s all about healthy trees,” says Anderson.
Anderson credits his son Cody, a high school teacher, as the catalyst for expanding the sugaring operation at their Meetinghouse Hill Tree Farm, resulting in about 170 gallons of syrup. “Thanks to him I’m run off my feet this time of year; he’s always adding taps and bringing more sap,” says Anderson.
It takes about 40 gallons of maple sap to make a gallon of syrup. That’s because tree sap is mostly water, and generally 2-3% sugar in the form of sucrose. It also contains dissolved minerals, hormones, and other organic compounds that provide energy for growth. The percentage of sucrose varies by tree and with each sap run.
Sap starts to run not just because it’s getting warmer, but because atmospheric pressure outside the tree is lower than the pressure inside the tree. This forces sap up through the trees’ tube-like “zylem” layer that’s just beneath the bark.
“Actually the atmosphere is pulling the sap out of the trees. And then when the pressure gradient flips and it's higher pressure outside than inside, it shuts off,” says Dave Anderson.
Big temperature swings, common in spring, create the pressure gradient. Savvy sugar makers, like Anderson and his son, keep a keen eye on the weather forecast:
“I've got three sources," says Cody Anderson. “One forecast that will give me 6 to 8 weeks, the other, the 10-day forecast. And my favorite one is Weather.gov. They've got a graphical forecast and you also get wind speed – because that's important. If the trees are feeling a wind chill, it might be a 40 degree day, but if it's cloudy and windy, there's no sap running. Or on a 35 degree day that is calm with brilliant sunshine, it could be running.”
“I teach a class about the science of maple sugaring,” says Cody Anderson. “So it's a bit of field work, actually tapping trees and boiling. But then a lot about the chemistry and physics and biology involved in taking sap from a tree. I've got one or two kids who have made maple syrup, and we talk about the differences in topography within a sugar bush that might dictate where you can put tubing and where you might need to run buckets.”
Sugar maples grow best in places with enriched soil and the right soil chemistry. Changes in soil and local bedrock, from one site to another, lead to differences in the taste of the maple syrup. They call it the soil’s “terroir.” The taste of the syrup is a product of the trees as well as the soil and bedrock, in addition to the way the sap is treated and boiled.
“People swore they could tell which sugarhouse in town produced the syrup back in the old days, in the 1800s,” says Dave Anderson. “Was it up on the hill? Or was it down in the valley? And there were different flavors. And so people make a big deal about unique flavor attributes.”
Weathering bedrock results in tiny silicates and elements, like nitrogen, calcium, phosphorus, and potassium which settle to the bottom of unfiltered syrup. It’s a silty substance that is present in raw sap and held in suspension until the sap is boiled.
“You can literally see the soil minerals,” says Dave Anderson. “It’s called ‘niter’ or ‘sugar sand.’ We filter it out to clarify the syrup, but it’s perfectly safe to taste.”
The niter was evident in some buckets of partially-boiled syrup that the Andersons were processing. Martin stuck a finger in to see what it was like: “It tastes like cocoa powder!”
Some enterprising maple producers use the sugar sand in a facial scrub, or use sap in body care products like body wash and lotion.
Thanks to the healthy attributes of the nutrients in maple tree sap, some producers skip the boiling process and bottle the sap itself. If sap is pasteurized, it can be safely consumed. With electrolytes like potassium and calcium, it could help with hydration. Sap also has abscisic acid, a plant hormone that may help regulate blood sugar levels, plus antioxidants that help fight inflammation.
According to Cody Anderson, though, to have a market for pasteurized maple sap as a product for direct consumption, you have to have an excess of sap.
“I think that's mostly happening in Vermont,” he says. ”The state of Vermont last year produced around 3 million gallons of maple syrup. The next six maple producing states combined did not match that 3 million gallons. New Hampshire is number seven on that list, with our roughly 137,000 gallons last year. We just don't have as many of the trees.”
Maple stands in soils with more calcium are generally healthier and grow faster, because calcium is a crucial nutrient for plant growth and overall plant health.
“You really can't fight the site,” says Dave Anderson. “So on a good maple soil site, the trees are going to do really well. Vermont has a better soil index for growing maple… There's more calcium in their bedrock. In New Hampshire, we have more acidic soils, so we get more oak, beech and yellow birch.”
People have been tapping trees for centuries, starting with Native Americans. Tapping could injure a tree if done excessively, but by limiting the number of taps and placing them properly, sap can be harvested for decades without any long-term harm.
New England is unique in the world to have this confluence of soil, trees and growing conditions that result, after a lot of effort, in maple syrup.
Something Wild is a partnership of NH Audubon, the Forest Society, and NHPR.
