Maple syrup (and maple sugar) is made from the concentrated sap from several specific maple trees, primarily in North America.
Today (as in the past) the production technique involves collecting the sap from the tree, and boiling it to remove the water and reduce the sap into sugar or syrup.
How to Make Maple Syrup: Tap Holes
In early spring, the maple syrup and sugar producer creates a tap hole in the tree bole, and hammers a spout or spigot into the hole. A bucket or bag is then hung beneath the spigot. Producers generally put in a new tap hole each season, and, to protect the tree, each tree is only tapped once every year. Only trees that are between 10-12 inches in diameter at chest height are considered strong enough to withstand tapping.
Each tap hole produces about 8-10 gallons of sap during the season. Sap buckets must be emptied several times during high flow periods; some modern maple sugar and syrup producers use plastic tubing, and some commercial firms even use a vacuum process to suck the sap out of the tree. At one point, commercial producers used a microbicide to stop the tap hole from drying out and extend the effective time for sap production, but these were discovered to harm the trees and their use is now illegal.
Sources
Perkins TD, and van den Berg AK. 2009. Chapter 4 Maple Syrup--Production, Composition, Chemistry, and Sensory Characteristics. In: Steve LT, editor. Advances In Food And Nutrition Research: Academic Press. p 101-143. (main source)
A bibliography of Maple Sugaring sources has been collected for this project.
