The aw of the syrup was measured in duplicate with an AquaLab Series 3water activitymeter (Decagon Devices, PullmanWA) according to the manufacturer's instructions. Certified water activity standards with aw values of 0.760 ± 0.003 (6.00 mol/kg NaCl) and 1.000 ± 0.003 were obtained from the manufacturer. The estimated sugar content as °Brix was determined by two techniques
used by maple syrup producers. Except for the cases where there were mold-damaged samples, the readings were taken in all three remaining samples.