Proton Nuclear Magnetic Resonance Measurements on Various Sugar Solutions

The dependence of low-field proton longitudinal relaxation rate on concentration was used to investigate water associations in sucrose, lactose, fructose, and glucose solutions. Data were analyzed in terms of Zimmerman and Brittin's theory. Results indicated that, at low concentrations, all four sugars bind nearly the same amount of water by weight and present analogous structures of highly mobile hydrated molecules. At higher concentrations, above 0.7 g/g of water, data suggested the formation of sugar associations of decreased rotational mobility, more so for the disaccharides than for the monosaccharides. For highly concentrated solutions (above 1.4 g/g of water), results were attributed to the depletion of free water and the formation of highly developed structures within the solution.