Mobility of water in various sugar-water systems as studied by oxygen-17 NMR

Proton decoupled oxygen-17 NMR transverse relaxation rates (R₂, s^-1) were used to measure the mobility of water in three sugar solutions, lactose (L), sucrose (S) and fructose (F), and their solution combinations, L : S, L : F and S:F, as a function of concentration and combination ratio (1:9, 1:1 and 9:1). The behavior of R₂ as a function of concentration for the single sugar solutions was similar at low concentrations. However, at high sugar concentrations deviations for sucrose and fructose were observed. The R₂ of the sugar solution combinations (L:S, L:F and S:F) at low concentrations was not influenced by sugar type or combination ratio, but only by the total concentration of the sugars present. A mass balance approach was used to predict the R₂ of the sugar solution combinations; however only at low total sugar concentrations did the equation adequately predict the experimentally obtained R₂ values.