BRIAN CHABOT: Welcome to Arnot Forest on a bright, but very cold, morning. You'll see I'm wearing gloves. And this is maple season. And I'd like to begin by telling you a bit about the history of where we get maple sugar from and how this relates to our other sources of sweetnesses.
The Europeans, when they arrived in North America, discovered that the Native Americans had already learned that maple trees were a source of sugar and had learned some ways of turning it into a more concentrated form of syrup at least that they used in their cooking. But before this happened, there were limited sources of sweeteners. The most common sweetener, and the oldest of our sweeteners, was honey, which was pretty widely distributed throughout the world.
But it wasn't until the British discovered sugar cane in India and then spread that to other locations that the cane sugar became more common. The colonists brought their iron pots to the Indians who were, up to that point, trying to boil the maple sap in hollowed out logs by putting hot rocks in the sap, which you can imagine is a very slow process. And we're standing in the middle of a sugar bush at the Arnot Forest, which is a place that we use for making maple products, but more doing research and education about the maple industry.
One of the properties of maple, in addition to its abundance in this part of the world, is that it has a high sugar concentration in its sap. The second property of maple, which makes it even more special, is that in the springtime with alternating freezing and thawing temperatures, the tree will pressurize, so that if we put a hole in the tree, the sap will come out under pressure. And the pressure is quite considerable. At its high spot, it can be about the same pressure as in your automobile tires.
One of the questions that is frequently asked about maple sugaring is, are we hurting the tree? Trees that live a long time-- and a maple can live up to 300 years-- have to be able to withstand a lot of things that happen to it. And maple is very good at this, which makes it a good species to work with.
If you think about our other sources of sugar,-- corn, sugar beet, sugar cane-- you have to kill the plant in order to get the sugar out of it. Maple is really the only species, only source of our sugar, where we can let the tree live and do this year after year.
This is a section of the tree. And in this section, you see the traces of past taps, holes in the tree. And one of the things you see is the coloration here. You see it here and here and here and here. What that coloration is is a natural antibiotic that the tree produces.
The third repair mechanism, of course, is the living part of the tree, which is the area just under the bark, will close the hole over. In a fast-growing tree, this only takes a couple of months, so the hole will be closed on the outside. We do temporarily damage the tree when we put a hole in it, but the repair mechanisms allow the tree to deal with that effectively.
Just a brief demonstration on the very simple process for tapping a maple tree. It takes a drill and a tap. This one is not connected to a collection line. But essentially, you get your footing solid. You find a place on the tree where you're likely to get some sap out of it, and we'll pick this spot here.
You aim your drill slightly upward, and you drill into the tree like this. Just put this little tap in here and take your hammer and tap it in like that till you hear a nice solid tap. And eventually, we will see sap dripping out of the bottom of the tap.
So this is what would be considered a modern sugaring operation. When you go above a couple of hundred taps. It's more efficient to use this extensive plumbing system. And the system includes these larger, what we refer to as main lines, which have larger ability to carry sap volume in them. And then these lines here are called lateral lines, and the piece going from the spout in the tree to the lateral lines is referred to as the drop.
So the sap flows from the spout through the drop through these laterals to the main lines. And then they'll be going down to even larger collector lines. And these larger lines are needed, because the volume of sap increases as we flow down toward the sugar house. So this is entirely on a gravity system.
PETER SMALLIDGE: The sap comes out of the tree at about a 2% sugar concentration. It's collected into large, stainless steel storage containers. We try to process it every day, so the sap doesn't spoil.
On most days, we'll run the sap through a reverse osmosis system, where the sap is forced under pressure through a membrane and concentrated from a 2% sugar to a 8% or 9% sugar. That reduces the amount of water from about 40 gallons of water down to about 10 gallons of water. So it's a significant savings on fuel to run the evaporator and also the duration that we have to heat the sap and make the syrup.
It feeds from the storage containers through this sap line into the evaporator, and we monitor the flow rate so that we're not moving too much sap at a time. We want to keep the sap level as shallow as possible, but not so shallow that we get a burning sap over the flame. So we can adjust the depth of the sap based on the flow rate coming in from the storage tank.
As the syrup moves forward, it becomes increasingly concentrated. The water is evaporated away, and we draw off the syrup based on the temperature. So we calibrated the temperature to correspond to a known sugar concentration, which is about 64% sugar.
When it draws off at a prescribed temperature, then we push it through a filter press. And then it pumps from the filter press into our finishing pan, where we finish it up to about 66% sugar, usually just under or at 66% sugar. We accumulate 30 gallons.
We reheat it to 190 degrees. And then from 190 degrees, we hot pack it into these drums, and those drums are used for storage during the rest of the calendar year. So we package it into the containers that we sell at the retail outlets.
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Join Brian Chabot, professor of Ecology and Evolutionary Biology, on a visit to the Arnot Research Forest to learn about making maple syrup.
In the early history of this country, Native Americans made it by putting hot rocks into maple sap collected in hollowed-out logs.
Later, iron pots brought by the colonists made it easier to boil the sap and dramatically increased the speed and efficiency of the syrup-making process.
In recent years, large-scale maple-syrup production advanced even further.