by Sanne Kure-Jensen
Sap from sugar maples has been boiled down into syrup since before colonial days. Each spring Vermont’s Shelburne Farms offers visitors a chance to experience this historic process, from selecting and tapping a tree to collecting and boiling sap into syrup. The sugarbush at Shelburne Farms is an outdoor classroom where students can explore history, math, science and their own connections to the natural world. Students on field trips experience the sugaring process, from measuring and selecting the right tree to drilling and tapping to gathering sap. Students calculate sap output and investigate impacts of weather and climate on both the syrup and on the trees long-term. They visit the sugarhouse, watch the boiling sap and talk with the sugarmakers.
Maple trees can be identified by their newer branches and buds. Their branches and leaves grow directly opposite each another on a stem, a characteristic shared among only three common Northeast trees: Maple, Ash and Dogwood. Maple buds are small, dark and pointy. Mature maple bark is a less reliable identifier because the lower bark of a mature Ash is very similar.
Shelburne Farms uses conservative criteria to place its taps. For one tap, they generally select a tree at least 44” in circumference at chest height. If the tree is 68” around or larger, it can support two taps; if it is over 78” around, it can support three. Most people believe that tapping does not hurt trees. (Educators compare drilling to getting a mosquito bite.)
The sugarmaker searches for tap scars from previous years and stays at least 2” to the side and 5” above or below them. She aims the drill slightly up as she bores in so that the sap will drain out, making a hole 2” to 2.5” deep — slightly longer than the length of the metal spout. When using tubing, drill the holes 1.5” deep. Most professionals mark their drill bit to the proper depth.
She clears out any sawdust from the hole with a clean stick or nail. (Never blow into the hole or you may force sawdust deep into the hole and contaminate the sap.) She inserts the spout and gently taps it in with a hammer, then hangs the bucket and attaches the cover to keep out rain, snow and wildlife.
Shelburne Farms has over 500 taps in its sugarbush and they collect the sap using a combination of traditional buckets, which require frequent emptying and commercial tubing. The tubing runs downhill from the taps into central collection tanks. Most of the Farm’s buckets are set up near the sugarhouse as an educational tool, so school groups and families can experience collecting the sap. Large commercial operations, in contrast, may have thousands of taps, with extensive tubing networks. Learn more about Vermont sugarmakers at http://vermontmaple.org/how-we-make-it.
To make maple syrup, the sap is boiled in a large stainless steel pan, called an evaporator, which has a series of chambers in it. Fresh sap comes in one end of the evaporator and as it flows through the chambers, the water boils off, the sap thickens and the sugar caramelizes and darkens. Sugarmakers use a hydrometer, which tests density, to determine when the syrup is done. They may also monitor the boiling point. Water boils at 212 degrees F, sap at a slightly higher temperature and maple syrup at 219 degrees F. The finished syrup is filtered and graded by flavor and color. Learn about syrup grading at http://vermontmaple.org/maple-products/maple-syrup.
Shelburne Farms uses a traditional wood-fired firebox, or arch, to heat the sap in the evaporator. About every six minutes, the sugarmaker inserts long, thin pieces of firewood, which burns extremely hot. By contrast, many commercial operators use oil or propane boilers.
It takes about 40 gallons of sap (2-6 percent sugar) to make one gallon of syrup (70 percent sugar). To reduce boiling time and energy use, large commercial growers often use a Reverse Osmosis (RO) process to remove some water from the sap before boiling. The long cupolas on the roof peaks of many sugarhouses have open sides that vent the enormous amount of steam generated by the boiling process.
Weather & Season Length
Ideal sugaring weather has mild days (40 to 45 degrees F) and frosty nights. During warm days, the tree converts stored starches in the roots to sugars. The warm days and cold nights create pressure in the tree that drives this “sweet” sap up the trunk towards the branches and buds (and into sap buckets!) During cold nights, the pressure subsides and the sap flow stops. Some sugaring operations limb up the trees in a sugarbush in an effort to extend the season. When sap reaches the lowest buds and they swell open, the chemistry and flavor of the sap changes and the sugaring season will be over for that year.
Shelburne Farms offers open houses, public workshops and education programs for schoolchildren and families during sugaring season. On March 23 and 24, Shelburne Farms hosted hosting a Vermont Maple Open House Weekend. Visitors joined the Shelburne Explorers 4-H Club for a pancake breakfast, learned about woodland wildlife with live bird-on-hand presentations and explored the sugarbush. Find more Vermont events celebrating maple sugaring at http://vermontmaple.org/events and Shelburne Farms events at www.shelburnefarms.org/calendar.
Shelburne Farms is a nonprofit education organization whose mission is to cultivate a conservation ethic for a sustainable future. Shelburne Farms’ campus is a 1,400-acre working farm and National Historic Landmark on the shores of Lake Champlain in Shelburne, VT. A farm-based education center, Shelburne Farms is a partner and backbone organization for the Farm-Based Education Network. In addition to supporting the network, the farm offers many on-site programs, including their ABCs of Farm-Based Education workshop, Children’s Farmyard and school field trips. Shelburne Farms also supports related programs, including the Vermont Farm to School Network, Vermont Food Education Every Day (VT FEED) (in collaboration with NOFA-VT and Food Works at Two Rivers Center), Forest for Every Classroom, Sustainable Schools Project and more.
by Sanne Kure-Jensen