Maple Science

MAPLE SYRUP SCIENCE

2025 Educational Activity

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Explore how chemistry, optics, and mathematics are applied to classifying maple syrup. Science helps decide who becomes a Royal Champion!

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For Educators

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There are many kinds of maple syrup! The different classes are decided by colour. The colour impacts the taste and flavour. The darker the colour, the stronger and richer the taste. So how do we measure the colour of the syrup to place it in the right colour class?

+ Why does maple syrup come in different colours?

+ How do we know when it's really maple syrup?

Measuring Colour

We determine the colour class of maple syrup based on the amount of light that moves through it.

Spectrophotometers measure how different wavelengths are absorbed when they pass through a liquid.

Colourmeters measure light transmittance through a liquid.

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Measuring Sugar

To confrim that maple syrup can be called maple syrup, we have to know how much sugar it contains. To measure sugar, we use something called the Brix Scale. The number on the Brix scale tells you what percentage of a liquid’s weight is sugar. For example, if a liquid has a Brix of 10, that means 10% of its weight is sugar, and the rest is water and other things. The higher the Brix number, the sweeter the syrup! For maple syrup, the Brix value must be between 66-68.9° Brix when it’s ready for bottling.

Measuring Sugar

Brix can be measured and calculated in two ways:

Refractometers Using Index of Refraction

Hyrdometers Using Relative Density

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HYDROMETERS

Hydrometers measure relative density, which is also known as specific gravity. To understand how a hydrometer works, it helps to know a little about density and specific gravity:

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BRIX EQUATION

The relative density of a maple syrup sample in the hydrometer is then used to calculate the concentration of sugar using a Brix Equation.

Refractometers

Refractometers measure concentration of sugar using the way light bends as it moves through a substance.

About

Brix equation

the index of refraction:

What is

uding index of refraction:

refraction?

Examples

How do

refractometers work?

Index of refraction

Did you know?

Maple syrup is an area of serious study! Agriculture and Agri-Food Canada (AAFC) has been conducting research on the flavour of maple syrup since 1998. AAFC, and researchers at the Food Research and Development Centre, and the Centre ACER, have been working to name the different taste categories of maple syrup. They have come up with this wheel as a guide, with 13 categories! Do you think you've tasted them all?

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Reflection

What method do you think is most effective in analyzing maple syrup? Why? Evaluate the pros and cons of each method using the following page:

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Learn more about maple syrup in Ontario at Maple Weekend 2025. Find a maple syrup producer near you! Take the survey:

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For Educators

Curriculum Connections

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Learning Outcomes

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inDEX OF REFRACTION EXAMPLES

Air has an index of refraction close to 1 since light moves almost as fast in air as it does in a vacuum. Water has an index of refraction around 1.33, meaning light moves about 1.33 times slower in water than in air. The index of refraction for maple syrup is usually around 1.50.

Example:

Steps to Convert Specific Gravity to Brix:

Let’s say you measured the specific gravity of a sample and found it to be 1.350. You can use the Brix equation to find out if this sample is maple syrup: So, the sugar concentration of the sample would be approximately 90.9% by weight. Too high for maple syrup!

1. Measure the specific gravity (SG) of the solution using a hydrometer. 2. Subtract 1 from the SG value. (This removes the reference of water's density, which is 1.0000). 3. Divide the result by 0.00386. 4. The result will give you the Brix value, which is the percentage of sugar by weight in the solution.

Grade 11 Chemistry Chemistry of Matter C1.1: Analyze the characteristics of chemical reactions and their applications C2.4: Investigate the properties of solutions and how solute concentration affects a solution’s properties (e.g., density, viscosity).** Measurement and Chemistry of Solutions C3.1: Perform titrations and other quantitative analyses to measure concentrations. Grade 12 Chemistry Organic Chemistry C1.4: Explain the chemical reactions involved in the preparation of organic substances C2.1: Analyze the physical and chemical properties of organic compounds (e.g., sugars in maple syrup) Solutions and Solubility C2.3: Investigate the solubility and concentration of substances in liquids Grade 12 Physics Optics C1.2: Explain the behavior of light as it interacts with matter. C2.3: Investigate how the color of materials is related to the absorption and reflection of light.

Grade 9 Science Understanding Matter and Energy: C1.2: Analyze the properties of solutions and describe applications of solutions in everyday life. C2.2: Investigate the properties of solutions and use appropriate methods and equipment to collect data. C3.1: Demonstrate an understanding of the interactions between light and matter Scientific Investigation SkillsA1.1: Plan investigations into the properties of materials and chemical reactions. Grade 10 Science Chemical Reactions C1.1: Analyze the characteristics of chemical reactions and explain the factors that influence them.C3.2: Investigate the properties of materials (e.g., syrup) and use laboratory equipment to observe changes Properties of Solutions and Mixtures C3.1: Investigate how the properties of mixtures (e.g., maple syrup as a solution of sugar and water) can be used to determine concentration.

Using a Hydrometer

1. Floating in a Liquid: The hydrometer is gently placed in the liquid. The more dense the liquid, the less the hydrometer will sink. A liquid with lower density will allow the hydrometer to sink further. 2. Reading the Scale: The hydrometer has a scale on its stem that shows the specific gravity of the liquid. As the hydrometer floats, the level of the liquid it’s floating in shows the reading on the scale. 3. Using the Measurement: The value on the scale tells you the relative density of the liquid being tested, which compares its density to the density of water.

Students will...

Remember - Define key scientific terms related to maple syrup production, such as sucrose, glucose, fructose, Brix scale, Maillard reaction, and spectrophotometer. - Identify the different classes of maple syrup and their associated characteristics (color, density, sugar content). Understand - Explain the chemical and biological processes that lead to different colors and flavors of maple syrup, including the conversion of sucrose to other sugars and browning reactions. - Describe how various scientific instruments (e.g., spectrophotometer, refractometer, hydrometer) are used to measure the quality and sugar content of maple syrup. - Understand the relationship between light absorption, color, and sugar content in the classification of maple syrup. Apply - Apply the Brix scale to calculate the sugar concentration in a sample of maple syrup using a refractometer or hydrometer. - Use a spectrophotometer to measure the absorption of light by a maple syrup sample and interpret the results to determine its quality and grade. Analyze - Analyze how the concentration of sugars (sucrose, fructose, glucose) in maple syrup correlates with its color and flavor. - Investigate how microbial activity during the maple syrup season impacts the chemical reactions that affect syrup quality. Evaluate - Evaluate the effectiveness of using optical methods (e.g., spectrophotometer, colorimeter) for grading maple syrup based on color and purity. - Critically assess the role of the Brix scale and other measurement tools in ensuring consistent quality and grading of maple syrup in the industry. - Judge how the scientific principles of chemistry and optics can improve the quality control processes in maple syrup production. Create - Design an experiment to measure the sugar concentration or color quality of maple syrup using scientific instruments, and propose improvements for better accuracy. - Create a model or diagram that illustrates how light interacts with maple syrup to determine its grade. - Develop a new method or technology for analyzing the chemical composition or flavor profile of maple syrup based on current scientific principles.

Colorimeters

With units designed specifically for testing maple syrup, these instruments measure light transmittance – or how much light passes through a sample of liquid. Using an LED light at 560 nm wavelength, they read the amount of light that makes it through a sample of maple syrup to the other side. Different colour classes of maple syrup fit into different ranges of % light transmittance – or the amount of light that makes it through the sample.

Why does maply syrup come in different colours?

Maple syrup season starts in winter. At the start of the season, when it is colder, maple sap has more sucrose. Later in the season, the temperatures get warmer, microbes or microorganisms mix in the sap while it is being collected. These microorganisms convert the sucrose to other kinds of sugars: fructose and glucose. Fructose and glucose are smaller molecules that react more during the boiling and processing of the sap into maple syrup in what are called nonenzymatic browning reactions. These browning reactions create a darker colour and a richer flavour. .

Syrup Colours

The classes that apply to Ontario maple syrup are:

Image from Ontario Maple

What is a Spectrophotometer, and how does it work?

A spectrophotometer is a device used to measure the amount of light that is absorbed or transmitted through a liquid sample. By analyzing the way light is absorbed at different wavelengths, spectrophotometers can not only measure the amount of light that makes it through a sample, but can also measure the concentration of compounds, like sugars, and check for consistency and quality.

How it works: 1. Monochromator: The light passes through a monochromator, which selects specific wavelengths/colors of light. 2. Sample: The light passes through the liquid sample. Some of the light is absorbed, and the rest continues to pass through. 3. Detector: After the light passes through the sample, the detector measures how much light has passed through. It compares the light intensity before and after it passed through the sample. The more light absorbed, the more concentrated a particular compound is in the sample. Different substances absorb different wavelengths of light. For example, sucrose will show absorption bands in a particular range of light known as “the carbohydrate region”, (1185–950 cm−1 with maple syrup specifically at 997-1054 cm−1) 5. Output: The instrument then shows the amount of light absorbed at which wavelengths. This is often shown on a display or as a graph, which can be converted into a reading that corresponds to the concentration of the substance you're measuring.

How a refractometer works:

1. Light Source: A small light is shined through the liquid on the refractometer. Usually, this light is from a built-in LED or flashlight. 2. Prism: The liquid is placed on a small glass prism in the device. This is where the light bends, depending on how thick or dense the liquid is. 3. Measuring the Refraction: As light enters the liquid, the amount it bends tells the refractometer how much sugar or dissolved solid is present. The more sugar, the more the light bends. 4. Scale: On the other side of the refractometer, there’s a scale that shows the percentage of sugar in the liquid. The user looks through an eyepiece and reads the number on the scale, which tells them the liquid’s sugar concentration.

Refractometers are useful because they give a quick, accurate way to measure sugar content without needing to do any chemical tests.

Brix Equation using Specific Gravity:

Where: • Brix = The percentage of sucrose by weight in the solution. • SG = Specific gravity of the solution (density of the liquid compared to water, typically measured at 20°C or 68°F). • 0.00386 is a constant used to adjust the specific gravity for the typical range of sugar concentrations.

Refraction

Light usually travels in a straight line. But as it passes through different materials, or mediums, it may slow down and speed up again. The change in speed causes light to bend, or refract. Light will refract more when travelling through a liquid with dissolved or suspended solids, like sugars. The more dissolved solids, the more dense a liquid, the more light will slow down and refract. So the way light refracts can tell us about what concentration of what kind of molecules are dissolved in a sample.

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Snell's Law Formula:

About the index of refraction:

Where:

• n₁ = index of refraction of the first material (like air or water).
• θ₁ = angle of incidence (the angle between the incoming light and the normal line, which is an imaginary line perpendicular to the surface).
• n₂ = index of refraction of the second material (like glass or water).
• θ₂ = angle of refraction (the angle between the refracted light and the normal line).

To calculate the index of refraction (represented as n), you can use Snell's Law. Snell's Law relates the angles of light before and after it enters a new material and helps determine how much the light bends when it changes from one material to another.

Relative Density/Specific Gravity

Density

Relative density/specific gravity is a comparison of the density of a liquid to the density of the same volume of water. Water has a density of 1 gram per cubic centimeter (g/cm³) at 4°C. • If the substance is denser than water, its specific gravity will be greater than • If the substance is less dense than water, its specific gravity will be less than 1. • If the substance has the same density as water, its specific gravity will be exactly 1.

Density is a physical property that compares the mass (or weight) of a substance to its volume (the amount of space it takes up). More mass packed in a small space (volume) means higher density. The formula is: Density=Mass/Volume

Specific gravity tells you how heavy or light a substance is compared to water. A substance with a higher specific gravity sinks in water, while one with a lower specific gravity will float.

Maple syrup must have a specific amount of sugar.

Maple syrup is can only be called maple syrup if it has a specific sugar content. It must have between 66% and 68.9% sugar by weight. Every colour of maple syrup will have a sugar concentration somewhere in that range – or else it’s not maple syrup! .

Converting refractive index to Brix:

To convert the refractive index (n) into a Brix value, and this relationship can be roughly expressed as:

Where:

• n = refractive index of the solution (measured by a refractometer).
• Brix = percentage of sucrose (sugar) in the solution.