A special alchemy on Virginia Road is turning the clear watery sap from over 120 Sugar Maple trees in Concord and Carlisle into a small supply of pure thick amber syrup that will be donated to food pantries in the Boston area.
Watch a video of how it's done here.
Overseen by the staff at Gaining Ground, a local nonprofit garden that provides organic produce for free, the sap is trucked in 30-gallon barrels from the trees to a small sugar shack at the organization’s headquarters at the Thoreau Birthplace.
The sugaring operation started about seven years ago with a few trees, said farm Coordinator Michelle De Lima. But it has grown into a larger operation in the two towns with the addition of an on-site sugar house and a shiny three-year-old stove where the sap is boiled down.
“This year we had a little less than normal, but it was better than we were expecting with the warm weather,” said De Lima. She said the trees collect the sugar in their roots in the fall, and the warmth of the spring “signals” the tree to send the sap upward to the buds.
“The trees started dripping in January this year,” said De Lima. And while the season isn’t quite over yet, she said most of the sap has been collected. She thought the trees produced about two-thirds of what they have in the past.
On a recent visit to Gaining Ground, assistant farmer Rafe Wolman stoked the stove as his cousin, Sofia Wolman, poured the sap into a large container where gravity pulled it into the stove.
Wolman said the fire must be very hot, so he prefers soft wood, like the pine he shoved into the stove about every five minutes to keep the sap boiling. He said the soft wood burns quickly. There are three boiling bins, each at a different level, so that as the sap reduces, and the steam pours out through the roof, the syrup is left in the lowest level bin.
Once it gets to seven degrees above the boiling point of water, or 219 F, it is siphoned off into a stainless steel bowl to be processed at another stove in the shack, ending up in sterilized canning jars for distribution. There are thermometers and gauges all around the shack that Wolman uses to test the temperature and density of the sap.
Wolman presides over the operation for hours at a time. The temperature must be “well above freezing” during the day for the sap to run. The taps in the trees only take a fraction of the sap.
“Like giving blood,” said Wolman, “there’s plenty left.”
He said it takes about 40 gallons of sap to make one gallon of syrup. That ratio and the complexity of the boiling process is what accounts for the high cost of real maple syrup, he said.
He said there are about 140 trees in the two towns that are tapped “once it starts to warm up.” De Lima said residents have come forward with a tree or two on their property, and there are taps on trees in public spaces like the library lawn and others.
Rafe said there is a filter so that bugs and other contaminants are kept out of the boil. He uses a gauge to control how fast it goes down into the stove.
“Too fast and it will not get hot enough, and too slow and it will burn,” said Wolman.
He said Norway Maples can also give sap, but it isn’t as thick as Sugar Maples and therefore takes longer to make syrup. Northern states and Canada are the biggest producers of syrup, although Wolman said Massachusetts is becoming the southern edge of the production.
“It’s so labor intensive,” said Wolman, a Belmont resident.
He said sometimes he works until the wee hours of the morning so he can process the sap as it is available. It is an irregular schedule, a day-to-day operation in early spring.
“You have to monitor it all the time that it is boiling,” said Wolman as he skimmed off impurities that collect on top of the sap, and smiled at the thick brew coming out of the stove.
Betsy Levinson can be reached at email@example.com.