Pulse NMR study of glass transition in maltodextrin

A pulse nuclear magnetic resonance (NMR) technique was used to study the glass transition in maltodextrins. The spin-lattice relaxation time (T₁) and spin-spin relaxation time (T₂) of different molecular weight maltodextrins at different moisture contents and temperatures were measured using the pulse NMR technique. T₁ and T₂ were plotted against temperatures. From the resultant curves, the state transitions were observed and the corresponding state transition temperatures were determined. The state transition temperatures were very close to the glass transition temperatures (T(g)s) determined with differential scanning calorimetry, suggesting a strong relationship between glass transition and proton relaxation behavior. Results indicate pulse NMR-based instrumentation could be very effective for the study of glass transition in food polymers.