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Self-reliance and sustainability in the 21st century.


How to Make Maple Syrup

By now, can’t you just taste that first pancake breakfast? Before you sit down to those flapjacks, though, you have to get this sap made into syrup. This article will walk you through every step of boiling and bottling. It’s not complicated but it is time-consuming and requires your full attention during certain points. Please remember, you will be handling hot, boiling, sugary liquid – be careful as you handle it and protect your arms and legs from splatters.

Throughout this process, you’ll be relying on your thermometer to tell you when to move onto the next stage. If your readings are even a couple degrees off, you’ll make sugar instead of syrup! Make sure your thermometer is working perfectly by calibrating it before each day’s boil. You can find quick calibration instructions online.

How Sap Turns into Syrup

Pure maple syrup is made by evaporating the water from the sap and caramelizing the sugars through a long and steady boil. The goal of this entire cooking process is to heat the sap to 219 degrees Fahrenheit (or 7 degrees above water’s boiling point). It can take many hours to get to this point but be warned that the last few degrees go quickly and can mean the difference between syrup and candy! The process is broken down into three stages:

First Stage: The Beginning Boil

Once you have a good bed of coals ready with extra fuel nearby (or your cook stove ready to go), pour your filtered sap into the pan and start cooking. Keep back one cup of sap (more on using this later). Leave 3 inches to 6 inches of headspace in the pan as sap can often foam up and boil over. Cook over high heat until you get a gentle rolling boil and then reduce heat enough to keep this boil going.

If you were unable to fit all your sap into one pan, you’ll need to preheat the extra sap in smaller pans. As the sap in the largest pan reduces, continue adding your additional pre-warmed sap until all the sap is boiling in one big batch. Do not add cold sap to this evaporator pan as that will “kill” the boil. Make sure to leave headspace for boil-overs.

While your sap is boiling, make sure you have clean jars with lids and a workspace ready for bottling. You’ll also need to get your filters set up. For the next stage, you’ll be pouring the hot sap through the thinner filter preferably into the pot you’ll continue boiling it in. Many folks use a cone-shaped filter holder or clothespins and dowels to hold the filter. Just remember that this sap is going to be very hot so do not plan on holding the filter while you pour. Continue checking the sap’s temperature and when it starts to near 216 degrees, it’s time to move on to the next stage.

Second Stage: Filtering and Finish Boil

not maple sap dripping through filter

Once sap reaches this range, you will need to transfer it into a smaller finishing pot with a more controllable heat source such as a gas burner. First shovel away coals or turn off heat to slow the boil. Pour the sap through the thinner pre-filter. Leave a few inches of headspace in this pot, too, as it can once again foam up or boil over. Do not put your empty evaporator pan back on the fire as this will scorch the pan which is nearly impossible to clean. After all the sap is filtered, put your pots on the secondary cooker and continue cooking at a rolling boil. Place thermometer in the pot making sure it’s not touching the sides or bottom.

Important! Watch your temperature closely from here on! All you’re looking for is the magic number of 219 degrees. This is the temperature at which sap turns into syrup. Watch for a few clues that you’re nearing this goal: the sap gets thicker, the surface takes on an oily appearance, and the bubbles get smaller and closer together. Sometimes the surface will develop a foamy layer – just skim off and discard. While the first stage seemed to take forever, temperatures spike quickly here and if you go over the target, you’ll most likely end up with candy. Remember the cup of sap we saved? This can sometimes rescue the batch if the temperature gets too high. Just remove the pan from the heat and add the reserved unfinished sap to lower the temperature. Continue boiling the batch back up to 219 degrees.

boiling sap with thermometer 

At this point, too, syrup can quickly boil over so watch the level in the pot. If it starts to boil up, lower the heat. If this does not stop the boil-over, use an eye dropper to put one drop of flavorless vegetable oil in the pan which can break surface tension much like a defoaming agent. Once you reach 219 degrees, remove syrup from the heat and cover it to keep the heat in. Prior to bottling, professional sugar makers also use a tool called a hydrometer to measure the density of the syrup. This is not necessary at the hobbyist level and only needed to establish the grade if you’re selling your finished product.

Third Stage: Final Filter and Bottling

You’re almost done!  Now all you need to do is filter one last time and bottle it up. This time around you’ll use a two-step filter: the thinner filter suspended inside the thicker filter. Pre-moisten filters with hot water and then carefully pour your syrup through this two-stage filter into a large pot. One sugar maker I visited with hung her filters inside an electric coffeepot. This works great because it keeps the syrup hot (syrup should be at least 180 degrees to 185 degrees for bottling) and it has a spout for filling jars. As you filter, do not wring out or twist the filters as this can stretch the fibers and distort the shape.

To fill your jars or bottles, carefully pour or ladle your hot, filtered syrup into the jar all the way to the top. Be sure to wear a thick glove to hold the jar as you fill it. Wipe the rims with a clean cloth, tighten the lid, and tip upside down so the hot syrup floods the container neck. Place the bottles on their sides on a thick towel and let sit for 24 hours, turning once halfway through this time. Once cooled, set upright and label. You may notice that your once-full jars have a bit of headroom – this is normal as the syrup shrinks a bit as it cools.

filling maple syrup jar 

Clean Up

After each batch, rinse everything (including filters) with hot water but do not use dish soap or laundry detergent which can leave residue that negatively affects flavor. When you’re completely done for the season, make sure all your tools are dry and store them away until next year.

Storing Syrup

Properly bottled pure maple syrup will keep for up to one year if stored in a cool, dark spot. It can also be frozen but will not harden completely due to the high sugar content. Once opened, be sure to refrigerate your syrup and use within six months of opening. If you notice any mold or discoloration, discard the contents as it may not be safe to eat.

What’s Next?

I hope your very next job is making yourself a giant stack of pancakes! After that, we still need to remove our taps and clean up everything for next year. My next blog will show you how to remove and care for your equipment and offer up a few fun ideas for using all this yummy maple syrup. If you don’t have time to wait for my next blog, I’ve created this handy Quick Guide to Maple Tapping with everything you need to know to make maple syrup today.

For more information on sugar making, look for Julie's books: Guide to Maple Tapping and Kid’s Guide to Maple Tapping.

The information and instructions contained within this blog series were gleaned through the personal sugar-making experience of the author, through interviews and case studies with professional sugarmakers, and through these resources:

Blumenstock, Marvin (author); Hopkins, Kathy (editor); How to Tap Maple Trees and Make Maple Syrup, 2007

Cornell Sugar Maple Research & Extension Program, Frequently Asked Questions for the Maple Producer, Forest Owner, and Consumer, authored by Peter J. Smallidge, Marianne E. Krasny, Lewis J. Staats, Steve Childs, and Mike Farrell, 2013

Heiligmann, Randall B., Ohio State School of Natural Resources, Hobby Maple Syrup Production

Massachusetts Maple Producers Association, Explaining Sap Flow, 2014

Michigan Maple Syrup Association, 2003, Facts and Figures

Nebraska Forest Service, Sugar Maple

Somerset County Maple Producers Association, New Options for the Maple Spout or Spile, 2012

Styles, Serena, Nutrition of Pure Maple Syrup vs Honey, 2014

United States Department of Agriculture National Agricultural Statistics Service, Maple Syrup Production, 2014

Vogt, Carl, University of Minnesota Extension, Minnesota maple series: Identifying maples trees for syrup production, 2013


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