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Maple Research Website

A maple research guide, in partnership between the University of Vermont and AgNIC

Syrup Production

From colonial times to the 20th century, sugar producers collected the sap by punching a small v-shaped gash in the maple tree, inserting a wooden or metal spout into the cambium, and hanging the bucket into which the sap dripped. This picturesque collection method has mostly given way to systems of plastic taps and tubing, which carry the sap from many trees to a central holding tank.

The flow of sap is triggered by a thaw following on a hard frost in the sunny days of late winter (February, March and April). Over a six-week season, the taps remove around 10% of a tree's sugar stores, in an average of 5 to 15 gallons per tree.

It takes around 40 parts of sap to make 1 part syrup. The sap contains around 2% sucrose at the beginning of the season, and only half that at the end; therefore, late-season sap must be boiled longer and has a darker and stronger flavor. Today, many procurers use energy-efficient reverse osmosis devices to remove about 75% of the sap water without heat, then boil the concentrated sap to develop its flavor and obtain the desired sugar concentration. They aim for a temperature around 7 degrees F above the boiling point of water, the equivalent of a syrup that's around 65% sugar. Maple syrup can be boiled down further to create maple sugar, which is approximately 90% sucrose.

Maple Terminology

Arch: The arch is the "stove" or stand underneath the evaporator pans to hold them in place. It may be made of metal or cinder block with fire brick on the inside, and a fire of wood or fuel oil is burned underneath to boil the sap. 
Brix Hydrometer: An instrument for determining density (percent sugar) of the sap or syrup.
Evaporator: A set of large shallow metal pans and an arch used for boiling sap into syrup.
Filter: Orlon, felt, cotton or special paper used to strain sugar sand from the syrup
Finishing Pan: A separate flat pan used to finish batches of concentrated syrup to standard density, commonly heated with propane.
Flue Pan: An evaporator pan used to boil sap, whith deep channels or flues in the bottom to increase the heating surface. Also known as a sap or back pan.
Gathering Tank: A metal tank used for transporting sap from the bush to the sugar house. The tank is fastened to a sled or wagon and pulled by horse or tractor.
Hydrometer: Equipment used to measure the sugar content of sap or syrup. 
Refractometer: Equipment used to measure the sugar content of sap or syrup.
Run: When the sap is flowing. 
Sap: Clear, water like fluid from the wounds in maple trees, with sugar content from 1% to 4%.
Spile: A metal or plastic spout, tapered at one end, that is driven into the taphole so that the sap can drain from the tree. They may have a hook attached to hold a bucket. 
Storage Tank: A large vat to hold the sap until it can be fed to the evaporator.
Sugar Bush: A woodlot or stand of predominantly sugar or black maples containing from 125 to 300 taps per hectare.
Sugar House: A building with equipment to turn maple sap into syrup, also known as a sugar shack.
Sugarsand: Material that is produced by boiling sap into syrup; it can be either somewhat slimy or very gritty.
Syrup: Sap that has been boiled until it is 66% sugar or higher. 
Syrup Pan: A flat evaporator pan used to further refine concentrated sap, where sap is cooked slowly to prevent burning. Also called a flat or front pan. 
Tank: A piece of equipment used to store sap. 
Tap Hole: A hole bored in a sugar maple, 11 mm in diameter and about 7.5 cm deep (exclusive of bark).
Tubing System: Small lateral lines made of plastic running from tree to tree and connected to a larger plastic main lines which carry the sap to the storage tank.