Grades of Maple Syrup
When the maple sap comes out of the maple tree it has no colour or flavour. Its look and taste is similar to water. But as the maple sap is boiled into maple syrup, it begins to change color due to a chemical process called “Maillard Browning”.
Maillard Browning is a chemical process involving amino acids, reducing sugars and usually requiring the addition of heat. The amino acids and sugars react when heat is applied, generating volatile chemicals (the chemicals your taste buds translate as flavour) and colour. The more reducing sugars are present, the more Maillard Browning occurs and therefore more flavour and colour.
When the Maple Sap leaves the tree, the sugars present are complex sugars which are two different reducing sugars (fructose and glucose) combined into one molecule (sucrose). The Maillard reaction does not occur with the presence of sucrose, so to get flavour and colour into the Maple Syrup the sucrose needs to be broken into fructose and glucose. As mentioned in “How maple syrup is made”, sap has a high level of bacteria after it leaves the tree. The bacteria feed on the bonds that hold the sucrose together, splitting it into the reducing sugars. The warmer the sap is the faster this process occurs and the more fructose is in the Sap.
The process stops when the sap enters the evaporator because the high temperatures kill the bacteria. So the amount of sucrose splitting that had occurred before entering the evaporator determines how much Maillard Browning will occur and what the colour and flavour will be in the end.
After the Maple Syrup has finished boiling and filtered, the Syrup is Graded based on its colour. There are five different colours or Grades for Maple Syrup. In the Canadian grading system, they are referred to as Extra Light, Light, Medium, Amber and Dark. The names of these Grades vary based on location.