Late March marks the beginning of the sugar maple season in the Northeast United States. Freezing nightly temperatures followed by a daily thaw causes the rise and fall of sap within the cambium of maple trees. During the daily thaw, sap that was pulled up within the tree falls with gravity. By tapping the tree, a syrup producer is able to collect the sap that is released through the tap via pressure. Cornell University's Director of the Uihlein Forest, Mike Farrell describes the characteristics of a maple tree. Opposite branches and thick, course gray bark are the best ways to identify a maple in the winter. He reviews previous tap holes which should be avoided when tapping each year. Spacing the tap holes out along the tree ensures that you will get the most sap flow out of the tree.
Michael Farrell, Cornell University's Director of the Uihlein Forest, taps a maple tree and uses a bucket to collect the sap. Today, large scale operations use plastic tubing, but for the small-scale maple producer, a bucket or a bag works well. Tools include a drill, 5/16 inch drill bit, a spile and a bucket with a lid. When tapping a tree, it is important to examine the tree's bark for scars or any other abnormalities. Look for a clean surface and drill in and back out. Examine the shavings to ensure that you have the white bark of the cambium where the sap is located. White shavings ensure that you've tapped the right portion of the tree and can help ensure that you'll get the maximum amount of sap from the tree.
Cornell University's Director of the Uihlein Forest, Mike Farrell, taps a maple tree and collects the sap with a bag. Similar to collection via bucket, a bag is also ideal for a small maple producer. Large scale operations use plastic tubing for more efficient collection of sap from the sugar bush.
Sap is collected with tubes in large scale operations. A simple set-up, illustrated in this video, uses gravity to bring the sap down the tubes. Cornell University's Director of the Uihlein Forest, Mike Farrell, explains the process of sap collection via tubing. A taphole is made, the tubing is installed and the sap is collected in a large container outfitted with an opening for the tubes. Freezing temperatures at night followed by thaws during the day create the perfect conditions for maximum sap flow. The tree draws sap up into the cambium during cold temperatures and releases the sap once it thaws. Gravity brings the sap downward through the taphole and into the collection tank. Although sap collection began with the use of galvanized buckets, large scale operations collect much more sap more efficiently with plastic tubing. Tubing should be periodically inspected for holes or leaks. Squirrels often pose problems for tubing systems as they like to gnaw on the plastic, resulting in small punctures. New technology such as the remote monitoring system, demonstrated in a subsequent video, allow large-scale producers to monitor their tubing system via nodes scattered throughout the sugar bush. The nodes send constant updates to smart devices and enable producers to detect pressure drops within the tubing at exact locations, thus decreasing the amount of time needed to detect and fix a leak and minimizing sap loss.
Large-scale maple syrup producers use vacuum tubing to maximize the collection of sap from the sugar bush while saving time. Michael Farrell, Director of Cornell University's Uihlein Forest, explains the vacuum tubing system. It begins with a tap in each sugar maple tree. The tubing flows from the tree through the lateral line and then to the main line which is divided into a wet and dry line. The dry line takes in the air and the wet line brings the sap down to the sap house. The vacuum pump is located at the sap house and is best installed in a way that uses gravity to its advantage, but it can work uphill when necessary. Vacuums help extract more sap from the tree during daily thaws. New technology with vacuum systems allows maple producers to monitor the system remotely and detect if there is a pressure drop in the tubing throughout the sugar bush.
Remote Monitoring Systems are a fairly new development within the arena of sugaring. This technology allows producers to monitor the tubing system set up within the sugar bush. If pressure drops, an alert goes out from nodes placed throughout the sugar bush to the producer's tablet or phone, relaying which line is losing pressure. This greatly reduces the time needed to find and fix a leak in a line. In many cases, squirrels chew holes in the tubing, causing pressure to drop leading to a loss of sap collection. Cornell University's Director of the Uihlein Forest, Mike Farrell, explains the remote monitoring system in this video.
The sap house is the first collection point in the sugaring process. It is generally located at the base of the sugar bush, which allows gravity to work with the vacuum pump in order to collect the most sap efficiently. All of the tubing flows downhill to the sap house where it goes through a series of pumps, filters and UV light which aids in the filtration process and the neutralization of any bacteria. From the sap house, it is pumped to the sugar house where it undergoes reverse osmosis, evaporation, further filtering and finishing.
Reverse osmosis enables producers to remove much of the water from sap before the boiling process. This greatly reduces the time and fuel needed to bring the sap to the adequate sugar content of 66 percent (by New York's standards). A high pressure pump forces the sap through a polymer membrane that allows water molecules to pass through but keeps the sugar molecules out. The sap becomes more concentrated as water is forced out of it and discarded. Mike Farrell, Cornell University's Director of the Uihlein Forest, explains the reverse osmosis process in this video.
After the sap goes through reverse osmosis and becomes concentrated, it moves to the sugar house where the evaporation process takes place. Mike Farrell, Cornell University's Director of the Uihlein Forest, explains how the concentrated sap travels through the evaporator's various pans. It eventually reaches the finishing pan, or the draw-off pan which is where the temperature and sugar content are measured before it's bottled. This evaporator is powered by gas, but many evaporators available for backyard producers use wood. A turkey fryer can be used but is not the most cost-efficient.
After the evaporation process has removed much of the water from the concentrated sap, diatomaceous earth is then added which acts as a final filter aid. Once the sap is brought to a sugar content of at least 66 percent sugar at 68 degrees Fahrenheit, it can be legally labeled as syrup in New York. Vermont and New Hampshire require a minimum sugar percent of 66.9. By taking readings with both a thermometer and a hydrometer, the syrup can be 'drawn off' when it hits the correct sugar percent at the correct temperature. In backyard operations, once most of the water has been evaporated from the sap, it can be finished in a pan on the stove-top. However, boiling all of the water off on the stove releases a lot of water inside of a home which can damage the interior. It is recommended that most of the water be evaporated outside and then finished inside if producing syrup at home.
Light, medium and dark amber are the three U.S.D.A grades of maple syrup in the United States. While New York requires that maple sap have a minimum sugar content of 66 percent, Vermont and New Hampshire require a minimum sugar content, or Brix, of 66.9 percent. All other maple syrup producing states without their own regulations follow the U.S.D.A regulations. Mike Farrell explains that each batch of syrup is graded based on its color. Whichever color grade the syrup is closest to, it will be labeled as that grade. Even if it is a shade darker, it must be labeled as the grade that its color most closely resembles.
Once maple trees reach the end of their lifespan and can no longer be used for sap collection, they leave behind lumber that has all the tap holes in it from previous years. Tap hole maple lumber was formerly used for firewood, but a new market is emerging for this specialty forest product that carries with it the story of maple sugaring. Mike Farrell describes how tap hole maple lumber can be used in many different applications, from furniture to flooring. Each board is also indicative of how sustainably the tree was tapped. Taps that are spaced too closely together often result in less sap collected year after year. Conservative tapping spaces the tap holes further apart to ensure that the stain columns do not intersect. This allows the most sap to be collected from the tree, year after year.