Here’s the evaporator in action. I built it next to a fence so I could tie a tarp over the set-up to keep the rain out, which worked pretty well. You know how you can sit and watch a fire for hours? When boiling down sap, you get to do this and be productive at the same time! Note the slightly wonky block placement. Things moved around a bit with the heat from the fire. Keep an eye on your bricks and your pans or bad things could happen!

If you’ve been following along, then you know that the big new experiment this March has been to make syrup out of boxelder tree sap. You can store your sap in food grade containers for a few days until you are ready to boil, as long as you keep it cool. Fresh sap is like fresh milk. You want to treat it the same way. I happened to have a few 6 and 7 gallon water containers and a root cellar that is currently at 40 degrees, so it was easy to hold the sap for a few days. A food grade 55 gallon drum with a lid and a spigot would be ideal. 

I built myself a boiler/evaporator out of cinder blocks and two stainless steel hotel pans. Total cost? About $65. If you have some cinder blocks lying around, or can find used hotel pans, you could do this for a lot less. The idea here is to keep the smoke up and away from your boiling sap, so you want the pan to fit down into the fire-box, sealing around the edges, not on top of it. You also want the heat and smoke to draw up and away. I just stacked a few square cinder blocks on some bricks in the fire pit to create a chimney. It worked pretty well.

I first boiled down a gallon of sap in the house, so I could see how the process worked and what it looked like at every stage. I started out in a large pot, and once the sap was reduced to about a quart, I transferred it into a small saute pan to finish. I happen to have a hydrometer (a special device that can measure the density of liquids – used in wine making among other things) and my sap right from the tree was about 98% water. Sugar Maple sap is about 97% (i.e. more sugar), which is why people don’t make boxelder syrup if they have sugar maples. For one gallon of sap, I ended up with just under 1/2 cup of syrup.

Just coming to a boil. This can take a while.

Once I understood the process (and had steamed up my house) I was ready to try out the new outdoor boiler. My larger hotel pan (12″ x 18″ x 6″) holds about 5 gallons, but to give it room to boil, I only filled it about 3/4 full. I also put some sap into the smaller pan, just so it didn’t scorch. As the contents in the larger pan reduced, I ladled sap into the smaller pan (which was also reducing, but slower, as it wasn’t right on top of the fire) and added more sap to the larger pan. I never let the pans get down to less than an inch of sap covering the bottom. As the sap boils, a “scum” or froth will collect on the surface around the edges. This is easily skimmed off with a large spoon (and flicked into the yard, which is kind of fun).

Almost ready…

In all, I boiled off about eleven gallons of sap over the course of an afternoon. (The process of adding more sap over and over gives you a darker finished product. If you are selling maple syrup, the lighter it is the “better” but I for one like a darker syrup.) Once mostly reduced, I poured the sap through a piece of cheesecloth (a bit of ash and debris is unavoidable – screen top covers for the pans would help) into a pot and took it into the house to finish. Have some sacrificial pot holders on hand, as they will get covered in soot from lifting the pans.

We have syrup. Remove from heat NOW!

How do you know when your syrup is done? Well, if you are clever and have a good thermometer, you took the temperature of your sap just as it first reached a rolling boil. Your syrup is finished when the resulting reduced solution reaches 7 degrees above where you started. What I discovered is that you can tell when your syrup is getting close, because the bubbles in the syrup get much smaller. Just as it finishes, your sap will start to expand in the pan and will boil over if you aren’t watching. It will also act like syrup rather than water and collect into a viscus drop when cooled on a metal spoon for a few minutes and then tipped out. I found I didn’t need a thermometer. You are aiming for 67% sugar/33% water in your finished syrup. Much more than this and you will end up with maple sugar rather than syrup. Much less and it won’t keep for very long.

Ready for storage. Note sugar sand.

As the sap reaches its final transformation into syrup, quite a bit of “sugar sand” or “niter” precipitates out of the solution. This is just a mix of minerals and is generally harmless unless you have lead contamination issues with your tree or equipment for some reason. This sugar sand can be filtered out or allowed to settle in your finished syrup overnight and then the clear syrup poured off. I used a piece of wool/poly blend felt as my filter. Too fine a filter (think coffee filter) and you will be there all day waiting for your syrup to pass through. Too course and you won’t remove the sand (cheese cloth will not work).

What I also learned is that if you plan on canning your syrup for long-term storage, don’t bring it up past 180 degrees or more sugar sand will precipitate out. I accidentally boiled mine again when canning, and ended up with a bit of sand at the bottom of my jars. No harm done.

How does the syrup taste? Very good. Not exactly like maple syrup, but definitely well worth eating. This has been a really fun project, and next year, it won’t cost me a thing.

I think my trees are pretty much done for the year. I got started a little late in the season, and we’ve had some warm nights due to rain, rain, and more rain the last few days. I haven’t collected much sap in the last two days. But I’ll leave the taps in for a week or so to see if we get another cold snap.

Now, I need to come up with a better name than Boxelder Syrup. Boxelder makes me think of the boxelder bug (a future post) which is harmless but very annoying. Any ideas?

Miles Away Farm Blog © 2011. Ancient coffer syrup, Senior trunk syrup, Old Casket syrup… don’t you love a thesaurus?

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