Maple syrup is made by boiling maple sap that is collected in the spring from Northern American or Canadian maple trees. This sap and the resulting syrup contain varying levels of sucrose, glucose, and fructose, with sucrose being the predominant sugar. Bacteria present in maple sap hydrolyze the glyosidic bond in sucrose, producing the invert sugars glucose and fructose. During the boiling process, the invert sugars in the sap are consumed by non-enzymatic browning reactions that give the resulting maple syrup its color, which determines the grade. Therefore, when there are more invert sugars present in sap, the resulting syrup will be darker. The sugar profiles of these products are thought to be influenced by a variety of environmental factors such as weather, elevation, and salt content (including salt due to proximity to a salted road). We have used various techniques available at our institution to qualitatively analyze maple sap and syrup samples, including by refractometry to determine the overall sugar content and by TLC to provide identity profiles of the sugars. Quantitative analysis has proven more difficult; we found that refractometry could not differentiate between the refractive indices of the sugars and TLC has not yet provided quantitative results. Other methods such as IR spectroscopy and UV-vis (performed in a basic solution) have not yet proved useful due to signal overlap. Because of our promising initial results, we are in the process of optimizing the TLC method for quantitative analysis. One method of analysis by titration using iodine and Benedict’s reagent has shown promising results for quantitative analysis of the sugars. This sugaring season, samples will be routinely collected from 10 trees and analyzed for their sugar content, pH, salt content and color before and after boiling (which will be carried out in our research lab) The sugars will also be quantified by HPLC if funding permits. Temperature, precipitation level, elevation, and distance from the road will be recorded for each tree and these variables will be compared to the sugar profiles of the trees to determine if any significant trends exist.

Analysis of sucrose, glucose, and fructose present in maple sap and syrup

2019 Spring National Meeting

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