title: Diffusion NMR as a new method for the determination of the gel point of gelatin.
abstract: The gelation of gelatin has been investigated using pulsed field gradient (PFG) NMR. For the first time, diffusion results have been used to determine the gelation point, which is indicated by a minimum in the self-diffusion coefficient of the free polymer fraction vs temperature. Biexponential analysis of the diffusion decay data allowing the diffusion of free and network-bound gelatin to be determined separately has been applied to provide an extended insight into the gelation process. Low-amplitude oscillatory shear rheology and time-resolved dynamic light scattering (DLS) as classical polymer characterization methods were applied as control experiments. All three methods yielded a gelation temperature of 24-25 degrees C for the cooling regime. Hysteresis effects could also be observed.
authors.affiliation: Institute of Analytical Chemistry, University of Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Brand
authors.forename: Sven
authors.initials: S
authors.lastname: Richter
authors.forename: Stefan
authors.initials: S
authors.lastname: Berger
mesh_terms: D004058:Diffusion; D005780:Gelatin / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012680:Sensitivity and Specificity; D013696:Temperature
chemical_list: D005780:Gelatin