Sixth-Graders Learn the Science Behind Making Maple Syrup
Sugaring, syruping or, as most say in the Catskills, sapping are terms used to describe the process of making authentic maple syrup. I say authentic as most grocery stores are flooded with “maple syrup” brands filled with high fructose corn syrup and flavoring.
The Manhattan Country School sixth-grade class arrived at the MCS Farm at the perfect time to start the sapping process. The students started by hiking to the sap bush, an area deep in the Farm’s forest. They learned to look for maple trees mature enough to be tapped and where on the tree to drill holes. Some trees may be able to sustain one bucket, while others two or three. Using a “bit and brace” hand drill, the kids took turns drilling holes one-and-a-half-inches deep. Once drilled, a “spile” or spout is tapped into the tree with a hammer. A bucket to catch the sap is hung and a lid to keep rain or snow out is attached.
On the day we started tapping it was a warm and sunny 45 degrees, which followed an overnight low in the 20s. These were perfect conditions for a sap “run.” Immediately after drilling and tapping, the crystal-clear sap began to drip. The kids instantly stuck their fingers, or in some cases their tongues, under the spile to taste this natural sugar water. Several kids exclaimed that the sap looked just like water, not the thick amber syrup we pour over pancakes. The raw sap is in fact approximately 97-percent water and 3-percent sugar and assorted minerals.
This conversation was the perfect transition to the next phase after tapping. Due to the sap’s rate of flow, in this case a fast drip, we were ready to collect the buckets the next day. Connecting the large gathering tank, or what we call the submarine, to the Farm’s vintage Ford tractor we headed back to the sap bush. We found many two-and-a-half-gallon buckets filled to the brim. The sixth-grade class members carefully took the heavy buckets from each tree, poured the sap into the gathering tank and hung the bucket back on the hook. This process continued until the tank was filled with 250 gallons of sap destined for the sap house.
After transferring the sap from the gathering to the holding tanks located outside the sap house we were ready to begin to boil. Using wood harvested at the MCS Farm and some scraps from a local sawmill, the sap is boiled in the evaporator pans. This two-pan system measures three feet by eight feet. As we feed the hungry fire with more and more wood, the sap continues to release steam and reduce in volume. As the liquid evaporates and the level drops, more sap is gravity-fed from the outside storage tanks into the pans. It takes, on average, 40 gallons of sap to make one gallon of syrup. As the maple sap increases in viscosity the color starts to change.
The boiling point of maple syrup was seven degrees above the boiling point of water on that day, in that place. Both barometric pressure and elevation play a role in determining the boiling point. The evaporating pan has a thermometer that the kids constantly check. However, there are some observations to be performed in this science project. The color has now obviously changed from clear to golden to light amber. The students notice the boiling bubbles changing from tiny, tight groups to large, slowly popping blobs.
Next we perform a “sheeting” test. Submerging a spoon in the liquid, we then remove it and look to see if the near-syrup comes off in droplets or sheets. The class now has several factors to consider. They determine the temperature to be 219 degrees, which is seven degrees above boiling water. The liquid is sheeting off of the spoon. The bubbles are now blobs. Before we can determine pure maple syrup we must perform one last test. We ladle the liquid into a hydrometer. The hydrometer measures the percentage of sucrose in a pure water solution. On the Brix scale we are looking for a level of 59.0. After accomplishing these tasks and getting the instrument readings needed, it is now time to “syrup off.” We open a valve on the side of the pan and let the boiling hot syrup flow through a filter and into a large container.
As we sit around the sap house sipping “maple tea” and waiting for the next batch, we have time to contemplate. How does the tree make the sugar? We turn to our lessons of photosynthesis and how the leaves on a plant turn the energy of the sun into a source of food. The chemical process of photosynthesis is the catalyst in creating sucrose or sugar. The plant, in this case a sugar maple, stores its sugary food in its roots throughout the winter only to be released in spring to grow new leaves.
The deeper question is, who invented maple syrup and what inspired them? Several historic names are considered until the class settles on Native Americans. In fact, native people would travel to the Catskills from the Hudson and Schoharie valleys to set up their “sugar camps.” Having no way of storing liquid syrup, these communities would boil the sap down to the raw sugar. “How did they know it could be done?” asked one student. That question is better left to legend and lore.
*You’ll notice several words or phrases in bold. This is to highlight the science, technology, engineering and math vocabulary students are learning and using during this seasonal process.