Canada's maple syrup grading system underwent a significant revision when the federal Maple Products Regulations were amended in 2015 and came into full force in 2016. The change replaced a patchwork of provincial letter-grade systems with a single national classification based on colour class and flavour descriptor. Understanding how grades are assigned requires familiarity with three interrelated measurements: sugar density expressed as Brix, light transmittance measured at a specific wavelength, and a sensory assessment of flavour intensity.
The Four Canadian Grade Classes
All maple syrup sold in Canada and exported under Canadian certification falls into one of four colour classes. The classes are defined by the percentage of light transmitted through the syrup at 560 nanometres, measured with a spectrophotometer or a standardised colour kit calibrated against IMSI reference standards.
Canadian Grade Colour Classes (2016 Standard)
| Colour Class | Transmittance | Flavour Descriptor |
|---|---|---|
| Golden | > 75% T | Delicate taste |
| Amber | 50–75% T | Rich taste |
| Dark | 25–50% T | Robust taste |
| Very Dark | < 25% T | Strong taste |
Sugar Density and Brix
Regardless of colour class, all maple syrup sold in Canada must meet a minimum sugar content of 66 degrees Brix, which corresponds to a density of approximately 1.32 grams per millilitre at 20 °C. The Brix scale measures the percentage of sucrose by mass in a solution, and a refractometer calibrated for maple syrup is the standard instrument used at the evaporator.
Syrup drawn too early — before Brix reaches the legal minimum — is classified as maple sap or substandard syrup and cannot be labelled or sold as maple syrup. Syrup boiled beyond the minimum will eventually crystallise on standing, as the sucrose concentration approaches the saturation point. Most producers aim for a working range of 66–67 Brix to allow for measurement tolerance and temperature variation during bottling.
Temperature Correction
Brix readings taken at temperatures above or below 20 °C require correction. At 60 °C, a raw refractometer reading of 65.5 Brix may correspond to a corrected density of 66.2 Brix at the reference temperature. Instrument manufacturers publish correction tables, and digital refractometers with automatic temperature compensation (ATC) have largely replaced manual correction in commercial operations.
How Colour Class Develops During the Season
The colour of maple syrup darkens progressively through the sap run. Early-season sap, collected when overnight temperatures are still well below freezing and the trees have not yet begun to metabolise stored starch, produces syrup with high light transmittance and a mild flavour. As the season advances and daytime temperatures increase, microbial activity in the sap rises and the concentration of amino acids and reducing sugars increases. These compounds participate in Maillard reactions during evaporation, producing the brown pigments and stronger flavours characteristic of later-season grades.
In practical terms, a producer running a well-cleaned evaporator in late March in Quebec is likely to produce Golden or Amber syrup. The same equipment run with sap collected in mid-April, when buds are swelling, will typically produce Dark or Very Dark syrup. The cut-off point varies by year and location.
Light Transmittance Measurement
The spectrophotometric method calls for diluting syrup to a standard sucrose content before measuring transmittance at 560 nm. The International Maple Syrup Institute publishes a standardised protocol for this measurement, and IMSI-certified colour kits containing glass standards at each grade boundary are used by packers, co-operatives, and inspection services to calibrate visual grading.
Visual comparison against physical colour standards is still permitted for on-farm grading in some jurisdictions, but spectrophotometric measurement is required for official certification and export documentation.
Flavour Descriptors and Their Regulatory Status
The flavour descriptors — Delicate, Rich, Robust, and Strong — are part of the official grade name under Canadian regulations. A label reading "Canada Grade A Amber syrup, rich taste" is the complete regulated description. The descriptors are not marketing language; they are defined terms with corresponding sensory thresholds assessed by trained evaluators against IMSI flavour reference standards.
Off-flavours such as buddy, fermented, or phenolic notes are grounds for rejection regardless of colour class. A syrup with the correct Brix and a transmittance that places it in the Amber class will still fail grading if it carries a detectable off-note.
The Previous Provincial Systems
Before 2016, Quebec used a system with grades No. 1 Extra Light, No. 1 Light, No. 1 Medium, No. 2 Amber, and No. 3 Dark. Ontario and other provinces used similar but not identical letter designations. The harmonisation process was driven partly by export market requirements — the United States and international buyers found the overlapping provincial systems difficult to reconcile — and partly by the need to align with international grading standards developed through the IMSI, which Canada and the United States both participate in.