Maple Syrup

If you live around maple trees, you could tap the trees to gather sap, and boil this down to maple syrup. Generally this is done in the north, as here we have a longer season of usable sap flow. You can collect sap on any maple tree when the sap is flowing and before the tree buds out.


Time to tap

I cut off a branch from a maple the other day, and a stream of sap came flowing from the wound. It is really hard to believe that in early February, we are having sap flow. But the trees have good thermometers, and this winter (2012) has been unusually mild in our area. We have had regular sunny days, and often temps into the 40's or above. The ideal temperature for sap flow are day temperatures above 40 and night temperatures below 32 F. The tree pumps up sap to get the branches and buds ready for spring, and during freezing temps, the sap is drawn back down to the roots for storage. This pumping action is ideal for collecting sap as it passes by the tap hole. We have some cold temps this weekend, but after that the 10 day forecast looks like above freezing in the day, and below at night. Perhaps it is now time to tap. Note this winter I have had the concern of tapping too early. If you tap too early and it gets cold and the sap flow stops, then the taps could dry up and be sealed off, causing you to miss later spring flow. For us a good sap season is 4-6 weeks, and for our area the good sap flow starts mid February to early March. Some areas like Vermont have 8 weeks or longer of sap flow.

Once the tree begins to open the leaf buds and the photosynthesis products return in the phloem (downward flow channels) it gives an unpleasant taste to the sap. So the available window is started by day time temps above freezing, and ended when the trees bud out. Some make syrup seasons are short, and some are long, it all depends on the weather.

Tools

The tools are really very simple. You need a drill that matches your tap size, some tubing unless you can hang your buckets on the tap, and a large flat pan to boil the sap down. It really is that simple. I tap low on the tree, and use tubing to drain the sap into food grade 5 gal bucket set on the ground. I found that one tap will offer 0.5 to 1 gallon a day, depending on the size and condition of the tree and the weather. You will want to check on the buckets each day. It is no fun discover an overflowing bucket. You hate to waste the sap!

If you use plastic buckets to collect sap or store syrup, be sure the buckets are food safe containers.

To set the spile, drill a hole angled slightly up, so the sap will run out. Drill to a depth of 1.5 inches for 5/16-inch spiles. Place the spile into the hole and lightly tap it in place with a hammer. If the sap is running, it will start coming down the spile within a matter of seconds.


Number of taps per tree

When you work tapping, you really can see how dynamic the sap flow is. You get the idea that you are tapping into the trees blood supply. You do not want to drain the tree of too much sap, or you could hurt the growth of the tree.

• Tap only trees with a diameter larger than 12"
• You can place two taps in trees with a diameter larger than 20"
• Limit yourself to three taps total in trees with a diameter larger than 26"

Boiling to syrup

Sap will spoil. It is dilute sugar water, and you can not really just leave it sitting. I found I had to process it daily.  If you have 60 taps, giving 0.5 to 1 gallon each, then you may have around 40-50 gallons of sap each day. We purchased a 2' x 4' evaporator pan, which we can make a fire under to boil down the sap. It takes us around 6 hours of flame to boil down 50 gallons to syrup concentration. The ending volume would be around 1 gallon of syrup.

Now this is an interesting point that I did not know before working with maple trees: not all maple trees have the same sugar concentration in their sap. There are genetic differences, and there are differences depending on how much light the tree is exposed to. We have maple trees in a forest, and our light exposure is basically the top of the tree. Our average sugar concentration is weaker than a tree in a fence row, obtaining light from all sides. Generally you hear of 40:1 ratios, and I calculated our ratios at 50:1. This means that I have to boil down 50 gallons of sap to get 1 gallon of syrup. The effort required for maple syrup is in moving the sap around, and in boiling down the sap to syrup.

My sugar shack is not a formal building, but a rather crude covering over a fire pit evaporator pan. I have built a low to the ground block frame on which to set the evaporator pan. Inside the concrete blocks, I set fire bricks to help protect the block from heat. At the far end, I have created a chimney to both draw the fire across the pan and smoke up and away from the syrup. I have supported the metal tube chimney with guy wires. There are 2 sheets of plywood supported on poles to provide cover from rain or snow.

I am ready to boil a batch when I have 30 to 50 gallons of sap ready to boil. I fill the evaporating pan with sap and light a fire in the fire box. Some like to preheat sap as possible to speed up the boiling process. Occasionally skim the surface of the boiling liquid to remove surface foam and other materials.

With a good fire, my pan will produce a huge rolling cloud of steam. Do not try boiling sap down indoors. If you are tempted to do so, just think about spreading 40 gallons of water around your kitchen. In such cases, I have heard of drywall falling off the ceiling, wall paper falling off, or mold taking over the home. The initial boil must be done outside or in a sugar shack!

Continue the process until the sap changes color and the boiling point begins to rise above the boiling point of water. Finished syrup boils at nine degrees (9° F) above the boiling point of water. As the temperature of the boiling sap approaches this point, boiling should be carefully controlled to prevent burning and overheating. If you are able to use a hydrometer or refractometer, you are looking for 66+% sugar. 67% sugar will form crystals over time on the bottom of the container, but I see that as some insurance against mold, and the crystals are edible.

Tear Jerker Syrup Burn

We do not take the sap to completion in our large wood fired pan. We get it close to final concentration, and then drain it off, and do the finishing boil on a smaller scale where we can monitor it more carefully. A wood fire is not a precise heat source, and you surely can not "turn it off" at a moments notice. There is real danger of over heating your syrup if you are not very careful. After tending a fire for hours, you do not want to burn a batch. This has happened to me, and I hope to never experience it again! Note: it is really hard to clean up your large pan from burned syrup.

I have the habit of always having a few gallons of fresh sap on hand to add to the pan if needed. If you are being called away from tending the pan, add more sap. It may stop the boil for a while, or leave you with weaker syrup than you hoped for this first stage, but at least you will not burn the batch.

When you finish off your syrup to the proper temperature or concentration, you will notice some solids that come out of suspension. There is a gritty particulate called "sugar sand" that you can filter from your syrup. Some batches have more than others, but it may surprise you how much sugar sand you will strain out. It is common for the maple syrup to bubble up and boil over as it approaches the final concentration. This last step requires constant attention.


Filtering & Storage

If you allow the raw syrup to set for a day or two, the sugar sand will settle to the bottom of the container. I have dipped pure syrup from the top of the settling pot, and processed it to finished syrup. To be most efficient with removing the remaining syrup from the settled sugar sand, you will want to filter it. To filter the raw syrup, heat it to 190 degrees, and pour it through pre-filters and finishing filters. These three filters are set on top of each other: 2 pre-filters, and 1 finishing filter. These filters are reusable year after year. The batch should be small for the syrup should remain hot for it to efficiently move through the filtering process. Some people have the filtering setup be within a pot that has a low heat applied, so that the syrup being filters remains hot.

If you heat the syrup above 200 degrees, more sugar sand can precipitate from the syrup solution. So in the finishing process post filtering, you want to heat to 190 to sterilize the syrup, but not heat above 200.

Once the syrup is at the proper concentration, it can be stored in the refrigerator till you are ready to permanently can it. We have found a bottle of syrup with a small amount of mold on the top surface. I measured the concentration of this batch, and it was close to 70 % sugar. This means that the ideal 67% sugar content will not prevent mold. You have to sterilize the syrup for storage in any long term storage. We plan to sterilize pint canning jars in the oven, and pour in syrup heated to 190° F. Place filled and capped containers on their side or upside down so the hot syrup sterilizes the lid or cap. After cooling, store in a cool, dry place.


Time Line for 2012

• Feb 9:   Sterilized spiles, T's and tubing.
• Feb 15: Laid out the location and dimensions of the sugar shack: 6x8 feet. Set 9 taps. Sap is dripping.
• Feb 16: Set the vertical poles and leveled the top plate of the sugar shack. Set 7 new taps. Sap is dripping. Collected around 6 gallons from the 9 taps of yesterday.
• Feb 17: Finished fire box placement. Set 3 new taps. Started first boil of 14 gallons sap.
• Feb 19: Arch complete with firebrick and chimney set in mortar. First boil of 35 gallons late in the afternoon. I have stoked the fire, and will let it burn out tonight. Not enough boil time to worry with a scorch so I can leave it unattended. (Pictures coming when I clean up the new sugar shack.)
• Feb 21: Ate our first syrup on waffles. MMMMM good. Set more taps today. Total of all taps now flowing: 39. Boiling down around 50 gals now.
• Feb 22: Third boil burned ;(. Now working to clean up the pan.
• Feb 29: Boiling again. I have quite a sap backlog! All buckets were full. Finished the roof on the sugar shack.
• Mar 2:   Finished all of the backlog and current sap, with all buckets empty on the trees. 4 gallons of excellent grade syrup! That was the longest boil we have done to date!
• Mar 6:   Boiling again.
• Mar 12: Last collection and boil. The sap is not as clean now as the first run, and the weather has warmed significantly. Buds are swelling, and we will pull the taps today. Total take in syrup was close to 10 gallons for our season.

Resources

• How to tap maple trees (pdf)
• Tips on tapping maple trees (web)
• Spiles, T's and tubing (web order)
• Boiling pan, stainless steel (web order)
• Air Flow and Velocities due to Natural Draft (web)
• Maple Trader Forum (web)
• Sugar Shack Design (pdf)
• Maple Syrup Grading (pdf)