High‐power ¹³C and ¹H nuclear magnetic resonance in dry gluten

Abstract

High-resolution, solid-state I3C NMR spectra of wheat gluten obtained under a variety of acquisition conditions are reported. These spectra are compared with the results from a 'H relaxation study of dry gluten in which the transverse relaxation times, the spin-lattice relaxation times in the rotating frame and the spin-lattice relaxation times in the laboratory frame at three different Larmor frequencies are characterized. It is concluded that I3C experiments, the proton transverse relaxation measurements and the rotating frame results distinguish between protein and lipid motional environments, whilst the laboratory frame proton spin-lattice relaxation results detect two separate protein environments. The relationship between the laboratory frame spin-lattice relaxation time constants and Larmor frequency is consistent with a model of macromolecular motion in which the polymer chains are held between cross-link points. Observed changes in the various proton relaxation times on removal of lipid or disruption of disulphide cross-links are interpreted in terms of the frequency and anisotropy of molecular motions in the gluten system.

Intermolecular Interactions and Phase Structures of Plasticized Wheat Proteins Materials

“…13 C CP/MAS NMR spectra of plasticized WP−I samples are shown in Figure where the WP−I spectrum is consistent with the results reported previously. − , The major resonances at 173, 54, 30, and 25 ppm are attributed to the carbonyl, C-α, C-β, and C-γ carbons of the WP−I, respectively. Minor resonances in the spectrum at 157, 138, 129, and 116 ppm are due to Arg, Tyr, and Phe .…”

“…13 C CP/MAS NMR spectra of plasticized WP-I samples are shown in Figure 5 where the WP-I spectrum is consistent with the results reported previously. [30][31][32][33][34][35][36]44 The major resonances at 173, 54, 30, and 25 ppm are attributed to the carbonyl, C-R, C-β, and C-γ carbons of the WP-I, respectively. Minor resonances in the spectrum at 157, 138, Wheat proteins consist of complex polymorphic mixtures of various kinds of polypeptides where intramolecular and intermolecular hydrogen bonding are expected to be the main interactions among the multicomponent systems with some minor degree of cross-linking via disulfide bonds.…”

“…In this paper, high-resolution solid-state 13 C and 1 H NMR spectroscopy was used to examine three plasticized wheat protein systems as it is a powerful technique to investigate the intermolecular interaction between protein molecules and plasticizers. NMR relaxation parameters also provide information on the molecular motion behavior of each individual component in the multicomponent system and phase structures of the whole plasticized protein-based materials. − Mechanical property testing and dynamic mechanical analysis (DMA) were also conducted. The structural and molecular motion information obtained from the NMR study was discussed with the properties of the materials to provide a comprehensive and fundamental understanding of the structure and property relationship of plasticized wheat protein materials.…”

“…NMR relaxation parameters also provide information on the molecular motion behavior of each individual component in the multicomponent system and phase structures of the whole plasticized protein-based materials. [30][31][32][33][34][35][36] Mechanical property testing and dynamic mechanical analysis (DMA) were also conducted. The structural and molecular motion information obtained from the NMR study was discussed with the properties of the materials to provide a comprehensive and fundamental understanding of the structure and property relationship of plasticized wheat protein materials.…”

pH Effect on the Mechanical Performance and Phase Mobility of Thermally Processed Wheat Gluten-Based Natural Polymer Materials

“…The two pH conditions were selected because they are far away from the isoelectric point. Solid-state NMR, as a powerful technique for multicomponent/phase polymer systems, − was applied to explore the phase mobility and composition of the materials, the behavior of plasticizers, and the intermolecular interactions between plasticizers and WG components. The mechanical properties and the glass transition temperature ( T g ) of the plasticized WG were also measured and correlated to the information on molecular motions and phase composition obtained from the NMR study.…”