Have you ever asked yourself the question, “how old is the sugar in my maple syrup”? Maple syrup is created by boiling down sap from sugar maple trees, concentrating the sugar into a viscous fluid. The sugars are produced through photosynthesis in leaves, and extra sugars are stored in woody parts of the tree. The sugars in maple syrup come from these carbohydrates stores – however the age of the sugars in the sap used to produce maple syrup has never been determined.
In a recent paper, Muhr et al. (Muhr et al., 2015, New Phytologist, in press) investigated the age of sugars in that delicious breakfast syrup. To do this, they used a radiocarbon dating method, similar to the one commonly used to determine the age of archaeological artifacts, which uses a carbon isotope signature to calculate the age of the carbohydrates released during early spring (when sap is harvested for maple syrup). They found that the carbon signature of sugar maple sap matches sugars produced 3 to 5 years previously, and due to the well-mixed nature of these sugars, the sap likely contains sugars that were produced greater than 5 years ago as well as recently produced sugars.
These findings have implications that go far beyond maple syrup. If the trees can use carbohydrate stores produced many years ago, this could make sugar maples resilient to environmental stress, including drought and insect attack, and allow survival of several years under poor growing seasons. It then becomes possible for sugar maples to maintain sap production even if the previous growing season was poor.
So the next time you’re eating maple syrup, think about how those sugars make sugar maples resilient, and how you’re eating a little bit of history.
Stay safe and stay informed,