HYDRATION STATE OF GELATIN 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 rela xation rates (R(2)) Of water-rich samples were measured at different t emperatures. The pH of gelatine solutions was adjusted with NaOH. R(2) shows characteristic dispersion as a function of Carr-Purcell-Meiboom -Gill (CPMG) interpulse spacing. Moreover, the more dilute the gelatin e, the less structured the gelatine sol and the slower the relaxation. For water-poor gelatines (0 to 66% water, wet basis), the longitudina l relaxation time (T-1), the transverse relaxation time (T-2) and the free induction decay (FID) were measured and the ratio of the initial amplitude of the slow relaxing T-2 components to the amplitude of the FID signal at 11 mu s (M0(src)/FID11) was calculated. These NMR curves and calculated values were also studied by means of multivariate stat istical analysis to determine which parameters were the best predictor s of moisture content and water mobility. Copyright (C) 1996 Elsevier Science Ltd