All pure maple syrup begins as sap from trees of the maple species. The predominantly used trees are the sugar maple (Acer saccharum) or , the red maple (Acer rubrum), and the black maple (Acer nigrum). The sugar content of maple sap ranges from 2.5 – 4%.
Maples are usually tapped beginning at 30 to 40 years of age. Each tree can support between one and three taps, depending on its trunk diameter. The average maple tree will produce between 9.2 to 13 gal of sap per season, up to 3.2 gal per day. This is roughly equal to 7 percent of its total sap.
Seasons last for four to eight weeks, depending on the weather. During the day, starch stored in the roots for the winter rises through the trunk as sugary sap, allowing it to be tapped. Sap does not flow at night because the temperature drop inhibits sap the flow.
Maples can continue to be tapped for sap until they are over 100 years old.
Tapping and sap collection
Production methods have been streamlined since colonial days, yet remain basically the same. Sap must first be collected and boiled down to obtain pure syrup without chemical agents or preservatives.
A hole is bored into the tree and a spout is tapped into the hole.
Maple sap used to be collected into buckets hanging on each maple tree. The sap would then have to be collected by walking through the woods to each tree and emptying the sap into a collection tank, usually on a trailer pulled by a tractor.
Modern sugar bushes now use tubing stretched to each maple tree.
The sap is collected via vacuum pumps into storage tanks.
Sap to syrup
The maple sap pumped up to the sugar house and run through a reverse osmosis system which removes half of the water content. The sugar content of maple sap is 2.5 – 4% sugar. The sugar content of the sap after the reverse osmosis machine is 5 – 8% sugar.
Maple syrup is made by boiling between 21 to 40 gal of sap (depending on its concentration) in an evaporator until 1 gal of syrup is obtained, usually at a temperature 7.4 °F over the boiling point of water.
The finished syrup has a of 66° or greater on the Brix scale (a scale used to measure sugar solutions). The syrup is then filtered to remove “sugar sand”, crystals made up largely of sugar and calcium malate. These crystals are not toxic, but create a “gritty” texture in the syrup if not filtered out. The filtered syrup is graded and packaged while still hot, usually at a temperature of 180 °F or greater.