Sunday, February 3, 2013

Bigleaf Maple Syrup

Home-made Bigleaf Maple syrup
When I was nine years old I ravenously read the Laura Ingles Wilder books and was quickly enamored by the pioneer lifestyle of the Ingles family, especially the stories about Laura’s early life in the Wisconsin woods, and Almanzo’s life in the forests of New York. One day, after reading about how Almanzo helped his father collect and boil maple sap to make maple sugar and maple syrup, I decided to try and make some of my own. We had a large wooded lot next to our house and I knew that there were several Vine Maples (Acer circinatum). The Vine maples were memorable because we used to climb up the trees until they bent down to the ground; like giant springs, the bent Vine Maple stems amplified our jumps, and launched us 10 feet or more off the ground. Without any instructions beyond Wilder’s anecdotes, I improvised my own sap collection system from an empty tin can nailed to a tree. To try and induce sap flow, I cut a small “V” in the bark above the pail. The days that followed were filled with anticipation, and ultimately disappointment, as my tap didn’t even yield a drop.

It wasn’t until I moved to Wisconsin for college, almost 10 years later, that I actually talked with someone who made maple syrup. Sugar Maple (Acer saccharum) and Red Maple (Acer rubrum) are most commonly tapped, but several other species of maple as well as birch, walnut, and hickory can also be used. I learned that my Vine Maple experiment failed because I improperly tapped the tree, at the wrong time of the year. Rather than cutting a “V” in the bark, I should have drilled a small hole 1-2 inches into the sap wood (xylem). Sap runs when the trees are leafless and the temperature swings above freezing during the day and below freezing at night. My major professor and best friend both had small sugar bush operations, but the timing never worked out for me to help them out and experience the process first hand.

When I moved to Victoria for my master’s degree, I started hearing about a festival and network of hobbyists and businesses on Vancouver Island that were focused on producing sap from our native Bigleaf Maple (Acer macrophyllum). Once again, a busy student schedule made it impossible to attend their events, but Katrina ordered a wonderful book on the subject called “Bigleaf Sugaring: Tapping the Western Maple” by two of the core members, Gary and Katherine Backlund. Here in Washington, Dr. Terry Maresca is also promoting Bigleaf Maple tapping; last summer, with school behind me, I made a point of attending her workshop at the Northwest Indian College Traditional Food Conference on Bainbridge Island.

Armed with good literature and hands-on instructions, I wasn’t about to let this winter pass without tapping a few Bigleaf Maples, so I ordered a dozen stainless steel taps, purchased some food grade plastic tubing, and started hording large empty water jugs from the neighbors' recycling.

Bigleaf Maple taps at Dad's house
In early December, I tapped a few stems on a large clustered Bigleaf Maple next to Dad’s house. Using a 5/16” drill bit, I bored 2 inch long holes at a slightly upward sloping angle into trees about 2 feet from the ground. My taps taper to an outside diameter of 5/16, so when I gently pounded them in, they fit snugly. To each tap I connected plastic tubing that allowed the sap to flow downwards to a "T" fitting, and then into a large receptacle at the base of the tree.

3 gallons of Bigleaf Maple sap
Theoretically, when the temperature and barometric pressure are adequate, sap flows up from the roots through long hollow xylem cells, to the branches and developing buds. Like a pin prick on a finger, the xylem cells, bisected by the drill, bleed sap until those living tissues heal, at which point a new hole must be drilled. Throughout December, our taps yielded only a few cups per week but during a stretch of cold nights and warm sunny days in mid January, sap production increased dramatically peaking with about 13 gallons of sap produced from 3 trees in about 3 days. According to the Backlunds, Bigleaf Maples in the Pacific Northwest can produce sap for 5 months from November until February, which is much longer than the 6 week season that is common for maples in the Northeastern woodlands.

Testing the specific gravity of Bigleaf Maple sap
The time had finally come to figure out how I was going to boil the sap down into syrup. Bigleaf Maple sap is only about 2-4% sugar with the remaining 98-96% being water. In order to produce syrup, the water must be evaporated off until the sugar concentration is about 66%. Small batches can be evaporated on a stove top, but high energy costs quickly make this method impractical.

The solution is to burn wood, which is practically free for the taking for anyone living in the Pacific Northwest that has a strong back and a little forest land. Traditionally, a large cast iron cauldron is suspended over a fire and sap is added as it is collected until the season ends and the syrup is “finished.” Open fires are notoriously inefficient and impart (for better or worse) a smoky flavor on the sap. Today, most people that make syrup use an evaporator that is made up of a steel firebox, and a stainless steel evaporating tray with a maze of chambers that allows for a continuous feed of sap in one end, and finished (or nearly finished) syrup out the other end. New to this enterprise, my evaporator is somewhere in between. I employed the same old rusty stove—salvaged from a sunken ship—that Katrina uses for making salt and simmered my sap in a 5 gallon pot placed on top of the stove.

My small sugar shack
Here in the Pacific Northwest where our winters are pretty soggy I needed to make sure that my open pot wouldn’t fill up with rainwater faster than I could evaporate it off, so Dad and I built the world’s smallest sugar shack (3’x4’) out of salvaged roofing and scrap lumber. With stove inside the sugar shack, I managed to reduce 5 gallons of sap into syrup, but it took an entire day. Commercial units boast evaporation rates an order of magnitude faster, so I set out to make some improvements.

Trying to evaporate sap on a stove
The problem with my stove is that the surface that is supposed to be conducting heat into my pan is ¼" steel, and the walls, which are supposed to be insulating the heat and forcing it upwards into my pan, are thin, rusted, and riddled with holes. A roaring fire wasn’t even sufficient to keep the sap boiling, so my sap evaporated leisurely, like a warm bath. To mitigate for the shortcomings of my stove, I replaced my large kettle with a stainless steel steam table tray (like the trays used at buffets), which has a larger surface area on the bottom, and when only filled partially with sap, managed to produce a gentle simmer. 

The improved evaporator
A nice boil
Still not satisfied, I decided it was time to modify the stove itself. My friend Ric helped me cut away a square section of the stove top with his oxy-acetylene torch to allow the steam tray table to nest inside the stove and come into direct contact with fire. The new setup is vastly superior; I can easily maintain a vigorous boil and I have increased my evaporation time three-fold.


Filtering warm sap that is ready to be finished
One of the tips that Terry shared with me was to reduce the sap to about 50% sugar in small batches as you collect it, and then store it in the freezer until you have several quarts. Terry likes to finish her syrup in larger batches, because the finishing process demands constant attention to ensure that you don’t drive off too much water and scorch the syrup. After three days reducing 4-5 gallons each day, I was eager to taste some syrup and decided I had enough condensed sap to finish.

Finishing the sap on an electric range
There are several ways to finish syrup, but as far as I can tell, the most important thing is that you have the ability to take your syrup off the heat source once the sugar concentration is 66-68%. Syrup above that concentration will crystallize into sugar, and below that, it is prone to molding. I finished my syrup in a large saucepan on our electric stove-top and monitored the sugar concentration with a thermometer. The boiling temperature of finished sap at sea level is about 219° F, and after about an hour of constant monitoring my syrup was finished. I poured it immediately into sterilized mason jars and screwed the lids on tightly.

My 13 gallons of Bigleaf Maple sap yielded about 1.75 quarts of syrup, which is a little better than a 30 to 1 ratio of syrup to sap (and means that sugar concentration in my sap was a little above 3%). While this doesn’t sound like a lot, it is on par with sap from Sugar Maples. The taste of my maple syrup is superb. Too bad it took me 24 years to figure out how to make it!
My first batch of Bigleaf Maple syrup

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  1. Superb it is!
    Thanks for the sample ;)
    Thoroughly enjoyed your write up of the process too.


  2. Makes me look forward to our syrup season in just a few weeks!

  3. My friend Carla of Wild Wines was just talking about tapping Big Leaf Maples in Southern Oregon!! I can't wait to try some, when will you be visiting us for some pancakes?

  4. Nicely done. Made my first batch of maple syrup this last weekend. I first reduced the sap with a homemade (open) brick fireplace--lid covering 98% of the pot--to where I could put it on an electric stove. I was originally afraid the syrup was going to taste like I smelled but as long as you double strain with a fine filter or cloth (I used coffee filters in a colender) the smoky flavor adds depth to the syrup.

  5. Hi Abe - a really interesting post - I love the pictures of your sugar shack. Though I'm thoroughly jealous, coming as I do from the UK where a tiny bottle of syrup, barely enough for a single batch of pancakes for my kids and I, costs a ridiculous amount of money. Thanks for the post.

  6. What is your opinion on the flavor and usage of raw big leaf maple sap?
    Just wondering friend :)

  7. Bigleaf Maple sap is mildly sweet raw. I use it in smoothies and muesli when I have it available. Last Monday we had what will probably be the last run of the year and today I am taking down the taps on my dad's trees.

  8. I've been tapping my bigleaf maples in Humboldt County (Northern California) on and off for over ten years. Good to see others on the West Coast in same endeavor!

  9. Great post. I am looking to find/purchase bigleaf maple syrup harvested/made in California...can anyone put me in touch with a CA purveyor....Thank you. Molly

  10. Intriguing. As a Vermonter transplanted to SW Washington, I am loving the idea, but dubious. You mention a range of November - February, but we still have a few leaves on our trees. You reckon it's too early for sweet sap? the weather is cooperating...

  11. Hi Abby,
    I just drilled a few test holes and did not get any immediate sap flow. The November-March tapping season information comes from the Backlund's book I referenced above. Last year I got the bulk of my flow in February and March, and the year before in January. This year I will probably wait until we get our first snowfall to set up all my equipment, since my best flows have been during and after snow-storms.

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  13. Hi Abe,
    Thanks for the great blog and for plugging our book. I'm just heading off this morning to day-3 of our 8th annual BIgleaf Maple Syrup Festival here on Vancover Island.

  14. Outstanding blog, do you think November is too early? It's been frosty & sunny

  15. I recently listened to the audiobook "Braiding Sweetgrass" by Robin Wall Kimmerer. In it, she talks about how natives first reduced the amount of water (and increased sugar content) by allowing the sap to regularly freeze overnight. In the morning, the ice at the top of your pot is removed. There were no or minimal amounts of sugars in the ice, thus using nature to assist the process without work/wood consumption. After several days, the remaining, more concentrated sap was boiled normally!

  16. How fascinating.... But, I'm still interested to know if you can tap and then indeed make syrup from vine maples? Is it worth it, taste, sap flow? Does anyone know?

    1. Aren't vine maples a bit spindly? I've tapped bigleaf maples in Humboldt County (Northern California) and got sap from my bigger trees, but the trunks of the vine maples that grow nearby seem too thin to drill, tap.

    2. Vine maples are indeed typically spindly (hence the name)... BUT... I tapped a couple this last year and was quite surprised how much sap they yielded for their size! Also, the sap was quite sweet to the taste; definitely sweeter than the big-leafs around here.

      What got me interested in trying this was that I have a couple of these trees on my property, and after pruning a couple of few small, low-hanging branches off one of them, during a mild cold-snap this last winter, the next day I awoke to frozen "sap-cicles" hanging from the ends of the pruned branches. They were very sweet and tasty... so much so, in fact, that the neighbor kids swiped (and ate) the remainder of them!

      Unfortunately, I have not yet gotten around to reducing the sap yet. It is hard-frozen in sealed containers in the freezer. I am just a hobbyist, and other things have taken priority I'm afraid. But, very soon, I will.

  17. wow! so interesting to read and see how maple syrup is made. I love to use maple syrup for desserts. It gives them a very refreshing taste and aroma. It's quite a hard work of making a syrup.

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