Hydration state of gelatine studied by time domain nuclear magnetic resonance (TD-NMR): a preliminary study

Hydration state was studied by time domain nuclear magnetic resonance (TD-NMR) in order to characterize water associated with macromolecules such as gelatine. In a first experiment, transverse water proton relaxation rates (R2) of water-rich samples were measured at different temperatures. The pH of gelatine solutions was adjusted with NaOH. R2 shows characteristic dispersion as a function of Carr-Purcell-Meiboom-Gill (CPMG) interpulse spacing. Moreover, the more dilute the gelatine, the less structured the gelatine sol and the slower the relaxation. ter-poor gelatines (0 to 66% water, wet basis), the longitudinal relaxation time (T1), the transverse relaxation time (T2) and the free induction decay (FID) were measured and the ratio of the initial amplitude of the slow relaxing T2 components to the amplitude of the FID signal at 11 μs (M0src/FID11) was calculated. These NMR curves and calculated values were also studied by means of multivariate statistical analysis to determine which parameters were the best predictors of moisture content and water mobility.