What exactly is Maple Syrup: a Vermonter's perspective.
Maple syrup is a uniquely American product which native Americans were making long before the arrival of Europeans. Knowledge passed down over centuries has insured the survival of what was once a primary sugar source and is now a luxury food product.
Maple syrup's flavor and color comes from a complex chemical reaction which occurs between substances in the sap as it boils. Neither the exact reaction nor the identity of the substance in the sap is understood. Chemists have been unable to unravel the chemistry to create an artificial maple flavor that tastes at all like real maple syrup. Thank goodness some things in life are acquired through effort and remain special.
Sap which flows from the tree is sterile, clear and has an average sugar concentration of about 2 percent, but this varies from tree to tree, the beginning of the season to the end and from year to year. Typically, the first sap "runs" are also highest in sugar content. Collected sap is boiled to a sugar concentration of about 66 percent, with approximately 40 gallons of sap required to produce 1 gallon of syrup.
Conditions under which sap will flow are well understood but Mother Nature cooperates in her own time. Night time temperatures in the teens and days which warm into the high thirties, accompanied by pressure changes inside the tree begin the flow of sap up the trunk of Sugar Maple. This can begin as early as February and continue into April. The season ends when the tree finally buds out. Since the old joke in Vermont is, "If you don't like the weather wait a minute and it will change", so it goes with sugaring. Sugar makers may have several days of perfect weather for sap runs, followed by conditions which prevent sugaring for weeks. In other words it is not work which can be planned for but for which one must always be ready to perform. Time and sap will not wait and sap may not be held long or it begins to spoil and will not produce quality syrup. Therefore, when there is a prolific sap run, sugarers may have to boil late into the night. In my opinion this is the perfect scenario for a spring Vermont night out!

