This final picture guide walks step-by-step through the process to do the finishing boil for maple syrup.
After harvesting your maple sap and doing the initial boiling, it is important to pay close attention as you near the end of your boiling. You will need to make sure that the syrup hits just the right temperature without boiling over!
Note: PracticalMechanic.com is reader-supported. When you buy through links on our site, we may earn an affiliate commission – at no cost to you. Thank you for your support!
Overview of Boiling Maple Syrup
This is part 3 of a 3 part series on how to make your own maple syrup. These are the links to the other articles in this series:
- Making Maple Syrup – Part 1 – How to Tap Maple Trees for Sap
- Making Maple Syrup – Part 2 – How to Boil Maple Sap
- Making Maple Syrup – Part 3 – How to Perfect the Finishing Boil (this article)
What You Need:
- large pot (6 quart)
- candy thermometer
- maple canning jars
- filter paper for pre-filtering
- synthetic filter for final-filtering
- filter stand or strainer
- refractometer (works MUCH better than old float-type hydrometers!)
How to Finish Boiling Maple Syrup – Step by Step Guide
This article assumes that you have already performed some amount of boiling on your maple sap outside on a fire or propane pot boiler, and you now want to finish boiling the sap to the correct consistency for maple syrup.
1 – Pre-Filter the Syrup to Remove Larger Debris
To perform this step, we will want to poor the sap from your outdoor boiling vessel into a large pot, for example a 6 quart pot and put it on the stove.
2 – Boiling the Maple Sap to 215°F
Once the sap is filtered, put it into the large pot and start up the stove and set it to a medium heat to get the sap boiling again. Insert your candy thermometer so that the bulb is submerged in the sap, but not touching the bottom of the pot.
Maple syrup boils at a higher temperature than water due to its sugar content. Water boils at 212°F, while maple syrup boils at 219°F. For this reason, you want to continue boiling your sap until it reaches a temperature of 219°F. In general, you want to boil the sap until it reaches a temperature that is 7°F above the boiling temperature of water. So if your area differs significantly from 212°F, add 7°F to the boiling point of water at your location.
A good practice to remove residue and reduce the amount of ‘sugar sand’ (or ‘niter’) that collects in your syrup, is to filter the syrup at 215°F.
3 – Mid-Filter the Syrup Once it has reached 215°F
Use the same type of re-usable paper filter as you did for the pre-filtering.
4 – Boil the filtered sap to 219°F
After filtering at 215°F, put the syrup back on the stove and continue boiling until it reaches 219°F.
You will also notice that the consistency seems to change as you approach the 219°F temperature. The bubbles will turn into larger, more viscous and stickier bubbles than before, like below.
There may be a temptation to go to higher temperatures in order to achieve thicker syrup. While this is the case, and the syrup will become thicker, it will also become more prone to crystallization. Below is some maple syrup that was heated to 230°F. After several weeks on the shelf, significant ‘rock-candy’ crystallization had occurred.
Once the sap has reached 219°F, let is boil at this level for another minute or so, then it is done.
Sometimes it is hard to read the thermometer, and it can seem a bit arbitrary when you stop boiling. If this drives you nuts and you want to be precise, get a refractometer and use it to measure the sugar content of your syrup. According to the International Maple Syrup Institute, ‘real’ maple syrup has between 66% and 68.9% sugar content.
You want the syrup to be at 66-68% on the brix scale (66-68% sugar content) because above 68% your syrup will start to crystalize in the jars.
I was surprised at how inexpensive these units are now. (I bought this refractometer). Instead of filling a tall cup or test-tube with syrup and using a ‘float-style’ hydrometer (prone to breaking due to the shock of submerging a glass instrument into very hot syrup), this unit just takes a couple of drops of syrup! It is way easier to use and more accurate in my opinion. This will allow you to achieve perfect syrup!
Here is my refractometer in use.
The maple syrup will boil for a long time at 212ºF, then it will start to climb. I watch the candy thermometer, and when it is indicating about 215ºF I start sampling with the refractometer.
I drip about 4-5 drops of syrup onto the viewing slide, then close the lid.
After that, look into the viewport to read off the % sugar concentration (brix value). The line between blue and orange indicates the % sugar in your syrup. In the image below, I was at about 66.4% (which is about perfect).
In the picture below, I show 2 different batches. The one on the left is at the maximum (68.9%) and the one on the right is at the minimum (66%) brix values to technically be considered maple syrup.
5 – Perform the Final Filtering
You are now ready for the final filtering. If you want to virtually eliminate all contaminants and sugar sand (niter) in your final product for a really nice finished product, use a synthetic filter for the final filtering. If you don’t care if there is some sugar sand in your syrup, go ahead and perform another paper filter step.
6 – As a Final Step, Can or Bottle the Finished syrup while it is still hot.
Then pour the syrup into the canning jars or Maple Syrup Bottles while it is still hot. When you hear a ‘pop’, you know that they have sealed.
If you started out with 5 gallons of sap, you will end up with somewhere around 20 oz of pure maple syrup. Of course this depends on a number of factors related to the sugar content of the sap produced by your trees, but can be used as a rule of thumb.
Grades of Maple Syrup
As you may know, the color of the syrup that you produce will change over the course of the maple sugaring season, so don’t be surprised if your batches look different from one another! Lighter syrup comes from the first sap that is harvested, and the color darkens as the season progresses. There is a maple syrup grading system established by the USDA to classify the grades of maple syrup.
Syrup can sit on the shelf indefinitely, but should be refrigerated after opening the sealed jars.
Congratulations! Enjoy your self-made maple syrup!
Thank you for reading, and I hope you found this helpful!