The Determination of Sucrose Content in Maple Sap Using Time-Domain Magnetic Resonance.

The natural variation of sucrose concentration in maple tree sap is investigated using time-domain magnetic resonance (MR). The current study, which includes a concise introduction to the relevant MR properties, is a demonstration of principle showing how the relaxation time constant T 2 and the self-diffusion coefficient relate to the amount of sucrose and ionic content present in the collected sap samples. T 2 and self-diffusion coefficient for maple saps from six different trees, each sampled weekly in the spring of 2019, were measured using MR. The results were plotted against the sucrose concentration of each sample with the aim of determining if either quantity could serve as the basis for a non-invasive sucrose measurement for maple trees. The T 2 relaxation time constant was found not to be a reliable proxy for sucrose content in maple sap as it showed sensitivity to the slight changes in sap chemistry throughout the season and natural variation from tree to tree. The diffusion coefficient, determined through a standard pulsed-gradient spin-echo experiment, was insensitive to the changes in sap chemistry and showed a strong relationship to sucrose content. A diffusion measurement is thus proposed as the most suitable candidate for a non-invasive sucrose measurement for maple tree sap.