A subzero H-1 NMR relaxation investigation of water dynamics in tomato pericarp

International audienceH-1 NMR relaxation times (T-1 and T-2) were measured at low field (0.47 T) in pericarp tissues of three tomato genotypes (Ferum, LA0147 and Levovil) at subzero temperature (-20 degrees C) and two ripening stages (mature green and red). The unfrozen water dynamics was characterised by two T-1 and three T-2 components. The relaxation time values and their associated relative populations allowed differentiating the ripening stage of only LA0147 and Levovil lines. But the three genotypes were unequivocally discriminated at the red ripe stage. The unfrozen water distribution was discussed in terms of specific interactions, especially with sugars, in relation with their osmoprotectant effects. (C) 2014 Elsevier Ltd. All rights reserved

NMR and DSC studies during thermal denaturation of collagen

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In vitro digestion of emulsions: diffusion and particle size distribution using diffusing wave spectroscopy and diffusion using nuclear magnetic resonance

International audienceDiffusing wave spectroscopy (DWS) is one of the few techniques enabling the investigation of structures and dynamics in turbid systems that is in the multiple light scattering domain. This makes it an important technique to study colloidal dispersions such as foam, gel or emulsion. In this article, DWS in both back-and forward-multiple scattering was used to monitor the in vitro digestion of turbid undiluted emulsions. Eight formulations were tested using two triglycerides, two emulsifiers and two emulsifier concentrations. The main goal of the study was to interpret the DWS data and compare the results to those from other techniques. We first extended the cumulants/moments fit method used for single scattering to obtain a particle size distribution (PSD) by DWS for multiple scattering. In the case of unimodal distributions, this compares well to PSD obtained from single scattering by dynamic light scattering (DLS). A second interpretation based on the multiple forward-scattering allowed the time-resolved diffusion coefficient to be measured. This was compared to the diffusion monitored by nuclear magnetic resonance (NMR) of turbid undiluted emulsions. Both techniques report similar diffusion coefficients, although NMR measures a true molecular diffusion in different environments whereas DWS measures the diffusion of supramolecular objects in the aqueous phase. These techniques are thus complementary, NMR resolving the kinetics of lipolysis, and DWS resolving the structural transitions, found to be first from a droplet to a vesicle and then from a vesicle to a micelle. In this study, the main formulation parameter influencing the digestion was found to be the type of triglyceride

Investigation of sodium ions in cheeses by 23Na NMR spectroscopy

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Magnetic resonance imaging studies of water interactions in meat

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1H-NMR study of water dynamics in hydrated collagen: Transverse relaxation-time and diffusion analysis

Water proton transverse relaxation times (T-2) and self-diffusion coefficients (D) were measured in randomly oriented hydrated collagen fibers. Three T-2 relaxation times were discerned indicating the presence of at least three,vater fractions in the collagen sample. The D values associated with each water fraction were determined. The diffusion time dependence of D suggests water motion is restricted by macromolecular structure. The experimental results are discussed with reference to the structural properties of hydrated collagen fibers

1 H NMR studies: dynamics of water in gelatin

Proton magnetic resonance was used to characterize the dynamics of water in gelatin. Both sol and gel states were investigated. Transverse relaxation rates (R-2) were dependent on the proton frequency measurement. (R-2) measured with the Carr-Purcell-Meiboom-Gill pulse sequence was dependent on pulse spacing. These observations were interpreted in terms of chemical exchanges between water protons and those of the macromolecules in the sol state, whereas in the gel state the contribution of diffusion through microheterogeneities in the sample seems to provide an additional transverse relaxation mechanism

Application of constant-time imaging to the determination of moisture profiles during the drying of paddy rice

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Molecular mobility in Medicago truncatula seed during early stage of germination : Neutron Scattering and NMR investigations.

International audienceFirst hours of Medicago truncatula (MT) seeds germination were investigated using elastic incoherent neutron scattering (EINS) and nuclear magnetic resonance (NMR), to follow respectively how macromolecular motions and water mobility evolve when water permeates into the seed. From EINS results, it was shown that there is an increase in macromolecular mobility with the water uptake. Changes in NMR relaxation parameters reflected microstructural changes associated with the recovery of the metabolic processes. The EINS investigation of the effect of temperature on macromolecular motions showed that there is a relationship between the amount of water in the seeds and the effect of freezing-thawing cycle. The NMR relaxometry results obtained at 253 K allowed establishing possible link between the freezing of water molecules tightly bound to macromolecules and their drastic motion restriction around 250 K, as observed with EINS at the highest water content. (C) 2013 Elsevier B.V. All rights reserved

Medicago truncatula seed germination and radicle growth: A microstructural NMR clarification

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