Collect maple sap, reduce it approximately 40x by boiling, pour it into a jar, screw on the lid. That’s the complete recipe for shelf-stable and wonderfully delicious maple syrup, one of the land's first and finest offerings during each Spring’s awakening.
This season was my first go at participating in the generously offered abundance of Wisconsin's maple trees, and the tricky step was the boiling, the 40x reduction to get form maple sap to maple syrup.
For the first round of boiling, I used a wok and propane burner. This is a set up used throughout Asia to cook everything from fried rice to pad thai to fish head soup to ma po tofu and kung pao pork. The key to some of these dishes is a raging hot wok and plenty of surface area. The high heat sears for taste and texture, while the large surface area allows food to be in contact with the pan and to shed moisture to the ambient air. Even a peanut-butter-toast-making westerner can spin up some delectable dishes with the right wok and burner. Germane to this discussion, the high heat and large surface area make the same setup a great choice for reduction of maple sap to maple syrup. The wok holds a couple gallons of maple sap at a time and, even at half power, the roaring burner reduces the sap volume by 6x or 8x in under an hour.
The wok and burner setup worked, but there were two issues.
1. It’s fiddly. Two gallons of sap boiled down to maple syrup makes six ounces of maple syrup. Pour the sap in, don’t spill all over, crank the burner, check on it occasionally, don’t forget or you’ll boil down to nothing and scorch all your hard work, turn down the burner, pour off the reduced sap, repeat. And repeat. And repeat. If you’re drinking beer or reading a book next to the wok, it would be fine. But any activities requiring long stretches of focus or time away from the burner are too frequently interrupted. It’s just too damn fiddly.
2. It’s expensive. Making maple syrup requires a lot of resources, including time, muscle and fuel. For the wok and burner, the fuel is propane. Propane is not so expensive. We run our grills all Summer for a nearly nominal expenditure. But a mega-burner and inefficient wok made me rethink the cost of propane. 8 gallons of sap resulted in about 30 ounces of maple syrup and required an entire 15-lb bottle of propane. For kicks-and-giggles, I guess this is fine. But it’s not great. A gallon of syrup would cost $60 or $70 for just the propane.
The solution to fiddly and expensive sap reduction is a wood-fired evaporator. There are many designs, from stacked concrete blocks to cut up metal drums to purpose-built cast-iron outdoor appliances. Right on site, I happened to have a stash of cinder blocks in the form of a hog roasting pit, so I quickly likened to the idea of repurposing the hog pit roasting cinder blocks as maple syrup evaporating cinder blocks.
This cinder block, wood burning evaporator was way better than the wok and propane burner. 1. Wood fuel is free. Kind of. 2. It’s less fiddly. Or at least less delicate. It’s fiddly in a way I appreciate. Outside from morning until evening, tending the fire, pouring in more sap, twacking logs with the ax, stomping around in the Spring-softened snow – that’s my kind of fiddly. That’s a recipe to a beautiful sleep and an absurdly delightful and keenly appreciated maple syrup pancake breakfast.
I boiled about 60 gallons over two days with this setup, resulting in about a gallon and a half of lovely syrup. The first batch of sap made light colored and sweet clean tasting syrup. New Glarus Spotted Cow. The second batch, from sap collected during the next 10 days, made darker, more robust, more complexly flavored syrup. Lakefront Riverwest Stein.
Next year, I’ll scale up. 5 trees, 2 taps per tree, maybe 25 days of collection = 200 gallons of sap, 5 gallons of syrup? Something in that ballpark. The wood burning evaporator will get a redesign for greater efficiency. I’ll have some days outside to shake off the winter blues, breathe cool air, listen to the first bird songs, soak my feet, freeze my hands. Until then, I’ll stay busy with 10-months of other backyard adventures, fueled by maple everything – pancakes, corn bread, banana cream pie, roasted pork, braised elk, sweet potatoes, barbeque sauce, vanilla ice cream, cocktails, coffee..