Grade B syrup is made from sap that is gathered later in the sugaring season and produces a heartier syrup with a more intense flavor. We like to use Grade B syrup for cooking as it has a much richer taste and holds up well in baking.
There is a complicated science behind what gives maple syrup color and taste. Everything from time harvested, sugar concentration, types of sugars present, time spent boiling, and microbial activity all influence the grade of a batch.
Typically, farmers produce delicate grade A golden syrup early in the season. This is due to the high sugar content the sap possesses in the late winter. As spring progresses, temperatures increase, and sugar contents decrease. Warmer temperatures also allow for more microbial activity in the tree sap. Decreasing sugar content and higher microbial activity both aid in producing a darker syrup.