(P06-002-25) Influence of Harvesting Month and Year on the Select Nutrients and Chemical Properties of Maple Sap From the Upper Peninsula of Michigan

Objectives: The primary objective of this study was to determine the influence of harvesting month and year on select nutrients and chemical properties of maple sap collected from the Upper Peninsula (UP) of Michigan.

Methods: A total of 19 maple sap samples (8 in 2023 and 11 in 2024) were collected from maple trees in the UP region between February and April of 2023 and 2024. The pH, titratable acidity (TA, %) and total soluble content (TSC, °Brix) of the maple sap samples were measured. Organic acids and sugars were quantified using UHPLC-DAD and HPLC-RI, respectively. The mineral content was analyzed using ICP-OES and the total phenolic content (TPC) was quantified using the Folin-Ciocalteu method. A two-way ANOVA was conducted using JMP software (version 18.0.1) to determine the statistical differences between various samples.

Results: The pH, TA, and TSC ranged from 5.99 to 7.85, from 0.008% to 0.033%, and from 0.73 to 2.73 °Brix, respectively. The pH, acidity and °Brix were significantly impacted by the harvesting year (p < 0.05). Malic acid was the most prominent organic acid in all the 19 maple sap samples collected over 2 years with values ranging from 29.52-1032.78 ppm. Among sugars, only sucrose was above the limit of quantification in maple sap ranging from 1 to 3 µg/mL, with no statistically significant differences based on month or year. The TPC in maple sap, expressed as gallic acid equivalent, ranged from 21.0 to 89.6 ppm, with neither year nor month showing a statistically significant effect on phenolic concentrations (p >0.05). Calcium (Ca), potassium (K), and manganese (Mn) were the most dominant minerals in maple sap samples.

Conclusions: The study highlights the impact of harvesting month and year on maple sap composition. Malic acid, sucrose, calcium, potassium, and manganese were identified as key components. These findings provide opportunities to enhance maple sap quality as a functional beverage.

Funding Sources: This research is funded by the Agricultural Marketing Service, United States Department of Agriculture (USDA), Award no: AM22ACERIL1017-00.