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When Is Syrup Finished Boiling?

September 19, 2018

This page will discuss a variety of methods you can use to make sure your syrup is perfect density. It is recommended to do a combination of methods to ensure that you are taking an accurate measurement. In addition to testing density of the syrup in your evaporator pan, it is best practice to re-check your density immediately before bottling. Sometimes, additional evaporation occurs between the evaporator and bottling phase so it’s always best to double check.

Long story short, when your syrup is between 66 – 66.9º BRIX, you have perfect density syrup! If density is higher than 66.9, your syrup is too dense and crystals may form at the bottom of your bottles. Slowly stir in a small amount of distilled water or sap until the correct density is reached. If the syrup is not dense enough, you need to do some more boiling/evaporating.

Method 1: Hydrometer Test

Maple Syrup Hydrometer

DESCRIPTION: A Hydrometer is a tool that floats in syrup to measure sugar density with a Baume and/or BRIX scale. Baume and BRIX are both measurements of sugar density. Similar to the way inches and centimeters are both measurements of length. That being said, BRIX is the much preferred scale because it literally means “percent of sugar”. For example, 66º BRIX means 66% sugar.

BENEFITS OF HYDROMETERS: They do NOT require batteries! Also, when used correctly, they provide very reliable results.

THINGS TO CONSIDER: Hydrometers are fragile. Handle with care! Also, hydrometer readings are affected by the temperature of your syrup sample. It is best practice to use a Murphy Compensation Cup for each reading. If a Murphy Cup is not available, use a thermometer and compensation chart should be used to calculate the proper reading.

Method 2: The Boiling Point

Maple Thermometer with 0-50 Scale

DESCRIPTION: As the sugar density increases, so does the boiling point of the syrup. Because of this, we know that the boiling point of our maple syrup should be 7ºF higher than the boiling point of water.

BENEFITS: Most evaporator pans have a fitting that will hold a thermometer in your pan while you are boiling. This is a nice quick reference and doesn’t require you to remove a sample of syrup from the pan to take a reading.

THINGS TO CONSIDER: The boiling point of water/syrup is NOT a constant. It fluctuates with environmental conditions such as altitude and barometric pressure. This means a maple thermometer should be re-calibrated in boiling water before each use to ensure best accuracy. Always use a hydrometer or refractometer to double check your density.

Method 3: Refractometer

Hanna Refractometer

DESCRIPTION: This is digital device that can measure the sugar density of your syrup with only a few drops of syrup in its well.

BENEFITS: Most refractometers can the sugar density of both syrup and sap, and have the ability to read samples at just about any temperature. These devices are compact, easy to transport and easy to maintain. They are often used in maple syrup competitions because they allow judges to take readings quickly while using only a small sample of syrup.

THINGS TO CONSIDER: Refractometers require batteries so make sure you have extras on hand. Avoid testing extremely hot syrup samples because the density of a steaming drop of syrup can change quickly. Refractometer manufacturers recommend that you recalibrate the refractometer with distilled water before each use, and if two back-to-back readings of the same syrup sample return drastically different readings, recalibrate again.

Method 4: Auto Draw Off System

Components of the Simplicity Auto Draw Off System

DESCRIPTION: This is system measures the boiling point of your syrup, just as we had explained in method 2 above. The difference between this system and a Thermometer is that this device will automatically draw syrup off of your evaporator when it reaches your specified temperature.

BENEFITS: If you have a lot of distractions while you are boiling, you may not notice when your syrup is ready to be drawn off. The result could be warped pans, scorched syrup or even a fire. In order to give you extra peace of mind, all Smoky Lake Auto Draw Off Systems have a built in safety feature that will sound an alarm if the syrup goes too far beyond your specified draw-off temperature. If an auto draw off system saves your pans/syrup just once, it has paid for itself.

THINGS TO CONSIDER: Auto Draw Off Systems may give you feelings of invincibility, but you should never leave your evaporator unattended. Make sure that power to the system is not disturbed. Make sure the automated valve is clean so that it can freely open and close. Make sure sugar sand does not build up in your pans as flakes could clog the automated valve. For accurate temperature readings, make sure the system’s syrup probe is submerged in liquid, not foam… Etc.

Also, remember that the boiling point of water/syrup fluctuates with barometric pressure. When you start boiling, you will need to take hydrometer or refractometer readings to determine the appropriate temperature for draw-off at that particular time. Always use a hydrometer or refractometer to double check your density.

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Joseph L Rundell

March 10, 2020

I am boiling with my new Starcat tomorrow for the first time. I am wondering at what temperature should I draw off. I am using a divided pan and am finishing on a gas burner. I will be testing with a hydrometer but I was wondering as a general rule the temperature to draw off at

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March 10, 2020

It sounds like you are asking about Method 2: Boiling Point? Using your maple thermometer, you will draw off at 7º above the boiling point of water. Here are instructions for using a maple thermometer: