January and February
Sugar made by the leaves during summer is stored as starch in the root tissues. As winter loosens its grip in February, the sugarmaker taps the trees. A sugar maple that is 10 to 12 inches in diameter at chest height will be about 40 years old and gets one tap. Some large maple trees in Vermont sugarwoods are over 200 years old! Vermont sugarmakers tap conservatively, so a tree yielding sap is like a person donating blood. They both have some to spare.
After the taphole is drilled a spout with either a bucket and hook or tubing attached is placed in the hole and gently tapped in place. Some sugarmakers have as many as 40,000 to 60,000 taps!
March and April
It’s sugaring season! Spring’s warmer temperatures coax sugar maple trees to turn stored starch back into sugar. Sap is made as the tree mixes ground water with the sugar. The sap is mostly crystal clear water with about 2% sugar. It takes 40 gallons of sap to make each gallon of maple syrup which has a sugar content of 66.9%. A typical sugaring season lasts 4 to 6 weeks. A pattern of freezing and thawing temperatures (well below freezing at night and above freezing during the day) will build up pressure within the trees causing the sap to flow from the tapholes. The sap from pipelines is drawn quickly back to storage tanks at the sugarhouse or a central collection area using a vacuum pump, while sap from buckets must be gathered by hand and into a gathering tank which transports it to the sugarhouse.
From the storage tanks, the sap is often put through a reverse osmosis or RO machine taking a percentage of the water from the sap before boiling. The evaporation process sends clouds of sweet maple scented steam billowing from the sugarhouse cupolas and steam stacks. An evaporator is where the boiling takes place. Stainless steel pans sit atop an arch, or firebox, where either oil or wood creates an intense fire. As the water in the sap evaporates, the sap thickens and as the sugar caramelizes it looks like hundreds of golden bubbles in the front pan. The sugarmaker tests the syrup’s progress by looking for it to sheet or apron off the edge of a metal scoop meaning it’s almost ready. When the thermometer in the pan reaches 219°F the syrup is ready to draw off.
Even though it looks like the finished product it will still need to be filtered, adjusted for density and graded for flavor and color. It’s a matter personal taste!
Reference: http://vermontmaple.org/how-we-make-it/