How to Boil Maple Syrup from Sap

Once you’ve collected sap from your maple trees, it’s time to turn your sap into syrup. In this article we’ll outline the process of how to boil maple syrup and share the exact method we’ve used for year to create delicious syrup on our small scale maple production.

The biggest variations in how to boil maple syrup mostly depend on the size of your operation. For operations with many trees and taps, you will likely be looking into a larger scale maple boil. This article is specifically for people with up to 20 taps who are looking for a simple and cost effective way to boil mapl syrup at home.

We’ve been tapping our own trees and making syrup for over 10 years and have a few addition resources to share:


A Simple Overview of How to Boil Maple Syrup

Once you’ve collected the sap from your maple trees, you will need to store the sap until you are ready to boil it.

Sap should be stored cold (the same way you would store milk). You can typically keep it outside in a container in the shade for a few days or a week if it’s been cold. You can tell the sap is spoiled when it starts to look milky or smell different.

Next you will need to boil the sap until enough of the water has evaporated. The goal is to evaporate water from the sap, concentrating the sugars to create maple syrup. During this process, the will be a lot of evaporation occuring – for this reason this is best done outside on an evaporator – remember you will need to to reduce your sap about 40 times to bring up the sugar content.

There are many options of what to use as an evaporator. Many people use a homemade evaporator using a specialized pan but you can also purchase an evaporator. You can see our exact process below for boiling maple syrup, but many people take their syrup inside for the final step of boiling it.

The process of boiling maple syrup requires patience, as it may take several hours to reduce the sap to the desired thickness for maple syrup. To determine when maple syrup is done, you can rely on its consistency and the temperature reached during the boiling process. One common method is to use a candy or maple syrup thermometer, ensuring that the syrup reaches approximately 219 degrees Fahrenheit (104 degrees Celsius). Additionally, the syrup’s consistency should coat the back of a spoon or form a thin, silky sheet when poured, indicating that it has reached the desired thickness and is ready for bottling.

Once the syrup reaches the proper consistency and flavor, filter it to remove any remaining particles, and then bottle the homemade maple syrup.

Boiling Maple Syrup
How to Boil Maple Syrup

Supplies You Will Need to Boil Maple Syrup

Boiling maple syrup is relatively straightforward but you will need some speciallized supplies. Below is a list of the supplies you will need with some links to purchase these. You can also see our article with a complete list of maple syrup supplies.

  • Evaporator – you can buy an evaporator or build your own.
  • Cooking Pot (if you plan to finish your syrup on the stove)
  • Candy Thermometer
  • Filter (or cheesecloth)
  • Jars or Bottles to Store your Syrup (we use a combination of specialized bottles and mason jars)

Additional items: stirring spoon, containers for transferring sap and syrup

How we Boil Maple Syrup

In this section we will outline exactly our method for boiling mapl syrup that we’ve developed over the years. It’s important to remember that there are other options for boilers and filtering (we’ve used several other boilers over the years).

Collecting and Storing the Sap

The first step once we’ve collected the sap from the trees is to store the sap until we have enough sap and the time to boil. We have converter a food grade barrel into our storage tank. The barrel is set up like a rain barrel with a spout at the bottom. By putting a few cinder blocks under the barrel, we can store our sap in the shade and open the spout to get new sap from the bottom of the barrel.

One common problem with storing sap - especially in the early part of the sap boiling season is that the water/sap can freeze and take a while to thaw in the barrel.  Keep this in mind when you are planning when to boil.  

Filtering - if there is a lot of debris in your sap, you can run it through a filter at this point.

Boiling in an Outdoor Evaporator

Our current evaporator is made from an old metal barrel with holes cut for maple syrup trays, and a smoke stack to keep the smoke adebris from getting into the sap. We build a fire inside the barrel and fill the trays with sap. We also keep a small pan on the top edge of the barrel. While the big pans get hot and boil, this small pan warms the sap so when to transfer it to the big pans it doesn’t totally ruin the boil. Throughout the day we keep transferring sap from one tray to the next and adding more sap.

By the end of the day, we will have one full pan of maple sap that is highly condensed and close to maple syrup.

How to Make Maple Syrup
How to Boil maple Syrup: our barrel evaporator

Bringing the Sap/Syrup Inside

Once the pan has cooled enough, we carry it inside for the night (of course you can do this all in one day). Sometimes we will put the pan on our woodstove overnight or for a day where it will boil off some more liquid, but usually we are ready to transfer it to a pot on the stove.

Once the sap is on the stovetop, we take the temperature. Over the years we’ve gotten much better being able to predict when the sap is close to finished so we rely less and less on the stove. It is possible to finish boiling maple syrup completely on the outdoor evaporater but we have better success with finishing it inside.

You want to boil the sap until the temperature reaches 219 degrees – this will only happen when the sugar content is correct. The last few degrees go quickly to make sure to keep an eye on it and stir. When the temperature reaches 219 – we always give a few good stirs and move the thermometer around to make sure the entire pan of syrup is 219 degrees.

Over boiling or underboiling your Maple Syrup: If you overboil your maple syrup, you will likely get crystalizing in your syrup as it cools.  If you have significantly boiled your syrup over 219 degrees, your best best is to continue boiling until you get maple sugar.

If you underboil your maple syrup and it doesn't completely reach 219, you may develop mold on your syrup during storage.  If it doesn't bother you too much, you can usually scrape off the mold and discard it.  If you prefer, you can also re-heat this syrup (Dave prefers to heat any syrup that has a small amount of mold).

Filtering Maple Syrup

Once you’ve boiled your maple syrup you will likely notice a lot of debris in the bottom of your pan. Over the years we’ve developed our own method for filtering our syrup. When we first started we found that the amount of debris clogged our filters quickly or we ended up with cloudy syrup.

As soon as our syrup cools a bit, we pour it into large mason jars and loosly add a lid. We set these jars on our counter for a day or two and allow the debris to settle.

Next we pour off the mostly clear syrup into a pan and reheat just until it’s warm. At this point is is more fluid and we pour it through a filter or cheesecloth. When we pour off the clear syrup you will be left with maybe 1/3 of the mason jar with syrup that has a lot of debris. We simply comine the jars and allow the syrup to settle again and repeat the process the next day.

Using this method we are able to get almost perfectly clear syrup without wasting much. Typically our last bottle is slightly murky and we simple use this for cooking or run it through the filter multiple times.

Best Maple Syrup Supplies
Boiling Maple Syrup

Bottling Maple Syrup

Before you bottle your syrup, make sure to sterilize glass or plastic bottles and lids by washing them thoroughly and then placing them in boiling water or using a dishwasher. We pour the hot maple syrup into the sterilized bottles, leaving a small headspace at the top (the smaller the headspace the less likely you will get mold.

Seal the bottles tightly with lids while the syrup is still hot to create a vacuum seal. Allow the bottled maple syrup to cool completely before storing it in a cool, dark place. Properly bottled, the maple syrup can be preserved for an extended period, ready to enhance a variety of culinary delights. We love to use it in traditional ways like on pancakes, but we also love to use it for baking or even making maple extract.

Storing Your Maple Syrup

Store maple syrup in a cool, dark place, away from direct sunlight and heat, to maintain its quality and flavor. Once opened, refrigerate the syrup to prolong its shelf life, and make sure the container is tightly sealed to prevent any contamination or crystallization. We typically store our syrup in bottles in the basement. If we have partial bottles of syrup, we use these first. Syrup can last upward of 3 years if bottled and stored properly.

Enjoy your Syrup!

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