An insight into molecular motions and phase composition of gliadin/glutenin glycerol blends studied by 13C solid‐state and 1H time‐domain NMR

Abstract

ABSTRACTMonitoring of the molecular motions and secondary structures of gliadin (Gli) and glutenin (Glu) in blends with 10, 20, 30, and 40% glycerol was performed by solid‐state (SS) and time domain (TD) NMR spectroscopy. Increasing the glycerol content increased the relative amount of β‐sheets and disordered structures, while decreasing α‐helices in Gli/Glu–glycerol blends studied by 13C CPMAS NMR. For ≥20% glycerol samples, the protein side‐chain mobility increased similarly for Gli and Glu. A higher proportion of α‐helices versus β‐sheets was found in Gli‐glycerol blends compared with Glu–glycerol blends. Glycerol acted as “immobilized” in 10–20% glycerol Gli samples and was found mainly “free” in 30 and 40% glycerol Gli/Glu samples. During temperature experiments, 30 and 40% glycerol amounts impacted the dynamic molecular behavior of the Gli and Glu proteins differently than lipids, as observed by TD‐NMR. The combination of TD‐NMR together with SS‐NMR showed details of the dynamic molecular variations in Gli/Glu protein structure and are promising techniques to monitor the molecular dynamics of plasticized proteins. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 739–750