Beaver Hill Plantation

Maple syrup is graded or categorized based on the flavor and how much light passes through (translucence). Variations are due to weather, soil, climate, point in season, boiling and more. The quality of all grades is the same.
At the end of every winter, the daytime temperatures rise just above freezing and at night temperature back below freezing. The water in the trees freeze and defrost creating alternating positive and negative pressure in the xylem sap transport system. The pressure builds and the sap flows allowing us to tap our sugar maple trees to make maple syrup. How is this natural watery liquid turned into the sweet maple syrup we have all grown to love?
In order to ensure that sap becomes that final product you put on your pancakes; maple producers must properly measure the density of the sap. We use a hydrometer to monitor and calculate the maple syrups density at a specific temperature. Maple syrup must be evaporated to a density between 66% and 67% Brix. If you have a density below 66% Brix, the syrup will ferment. If you have a density above 68% Brix, the syrup may crystallize. Maple syrup reaches the proper density at 219.5°F or 7.5° above the boiling point of water. This explains a lot of the basics but if you boil the syrup based on the same guidelines why does it look and taste different?

How Does Maple Syrup Get its Color and Flavor?

According to Steven Roberge, a Forestry State Specialist from the University of New Hampshire, "the pH of the boiling sap, sugar concentration, types of sugars in the sap, length of boiling time to produce syrup, the temperature outside, and even microbial activity all play a role in syrup color." 
Sugars such as sucrose play a huge role in the syrups natural flavor profile. When the sap leaves the of the tree and is introduced to naturally occurring such as bacteria and yeast the sucrose molecules (sugars) break down into simpler fructose and glucose sugars. The warmer the air and sap temperature, the more active the bacteria and yeast microbes become, and the more sucrose that gets converted. When the sap is boiled to reach the appropriate density and temperature a light brownish tint develops from a chemical reaction called the Maillard Reaction. This is a similar reaction that can be observed when baking cookies or bread. The more glucose and fructose sugars in the boiling sap the longer the sap boils, the darker the syrup will be.
If the temperature outside is colder then less of the sucrose molecules (sugars) will be converted into simpler fructose and glucose sugars causing the syrup to reduce less boiling time and browning resulting in a lighter grade syrup. 
If the temperature is warmer, then more of the sucrose molecules (sugars) will be converted into simpler fructose and glucose sugars causing the syrup to require more boiling time and thus be darker in color. 
As the season goes on temperatures build, sugar content in the sap declines, microbial activity increase, and the syrup color darkens. Flavor profiles tend to accompany each of the individual colors/grades. The longer the syrup boils the stronger the robust maple flavor. 
Golden Delicate- Delicate Flavor and lightest color
Amber Rich- Rich in flavor and color
Dark Robust- Robust flavor and dark amber color
The flavor profiles are also attributed to the natural organic substances curated from the environment in which the tree grows such as soils, tree-health, sap handling and processing, and weather. In the end, maple syrup grades are selected based on sugar density, flavor, and color which are all determined by the USDA grading system and so we grade the syrup we make accordingly.