Wednesday, February 3, 2016

Making Maple Syrup, Maynard MA

Maple sap collecting buckets are obsolete. Operators now create a web
of tubing connected to a vacuum pump = cleaner and less labor. 
Daytime temperatures above freezing followed by nights below freezing are optimal to promote and prolong the maple sap season, which typically lasts 4-6 weeks. Each tap into a tree is expected to generate 8-12 gallons. New tap holes are drilled each year because the tree reacts by clogging the area around the tap in an attempt to heal itself from the damage.

What is collected is about two percent sugar, processed to concentrate it to 67 percent, meaning that it takes about ten gallons of sap to make one quart of syrup. The tree species of choice is sugar maple (Acer saccharum, also known as rock maple) followed by black, red and silver maple. Sugar maples are preferred because of higher percent sugar in the sap and more sap yield per tree.

Locally, climate change is affecting the maple syrup industry.  The season tends to start 10-15 days earlier than it did decades ago, and of greater importance, is becoming shorter. Toward the end of each sap season the resultant syrup is darker and has a maple taste too strong to be sold as pure syrup. Instead it is used as flavoring for stuff like barbeque sauce.

Tubing gravity-feeds into a stainless steel container. Contents periodically
pumped into a tank on a truck to be transferred to a 'sugar shack' for 
concentration via reverse osmosis and heat evaporator.
With the advent of nights with above freezing temperatures the leaf buds begin to open and the sap develops a bitter off-taste referred to as "buddy" syrup. Sap collection stops when this starts. This week's prolonged warm weather may have been enough to trigger bud break, so that even if February gets cold again, this may be a lost year.

Expert advice on tree tapping is consistent - to harvest without causing harm do not tap trees under 10 inches in diameter, do not add a second tap until diameter exceeds 17 inches, and only go to three (and never higher) when trees exceed 25 inches in diameter. Some maple sugar operations are switching to a smaller diameter tap and not drilling as deep (5/16 and 1.5 inches versus 7/16 and 2.0 inches) and experimenting with tapping smaller trees, but there is not enough long-term experience to determine if the smaller taps mean that smaller trees stay healthy over years of use.  

Tap on too-small maple tree (Click on photos to enlarge)
In Maynard, most of the tapped trees in the woods south of Concord Street Circle are under ten inches in diameter; many are well under six inches. The practice risks doing trees grievous harm. Premature tapping and over-tapping (too many taps per tree) slows growth. It also weakens trees, putting them at risk for disease and rot. 

One newish question is how "green" the maple syrup industry can become. The old bucket methods have been superseded by networks of plastic tubing that connect trees to collection tanks. The process is either gravity driven, or else hooked up to pumps. Studies have also shown that plastic tubing will produce higher yields of cleaner sap and greatly reduce the labor involved with sap collection.

At the sugarhouse, the maple sap is run through a reverse osmosis system which removes about 80% of the water. Although the concentration process is still completed via an evaporator, using the osmosis process first saves lots of fuel. Evaporators can run on gas, oil or wood. Burning wood will put more carbon and smoke into the atmosphere, but it has the benefit of being locally sourced. And free.

The newest fad is to skip any concentration process entirely, and market "maple water," i.e., pasteurized maple sap. The taste is faintly sweet (under 100 calories per quart, meaning less than half what's in coconut water). Given the source, it is organic, non-GMO and gluten-free.

NOT IN NEWSPAPER ARTICLE: For readers deeply interested in maple tree tapping science and practice, the Proctor, Maple Research Center at the University of Vermont has many articles posted at this website:

One of the most controversial ideas is to turn maple tree tapping from a gathering to a farming process, akin to Christmas tree farming. Maple trees would be selected for high volume and high sugar content, then cloned to create genetically identical seedlings. The seedlings would be planted close together on easy-to-access land that can be fertilized, managed, etc. When trees are about ten years old the tops are cut off four feet from the ground and a vacuum-powered collector attached across the top of the stump. Not clear yet whether this will kill the tree, of if a new trunk will sprout from the roots. Even if the former, just pull out stumps and plant new trees. When compared to collecting from mature forest trees, estimates are that a maple tree 'plantation' could yield 20X-30X more sap per acre.