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The structural arrangement of starch polymers in presence of water is known to impact the functional properties of starchy products. In this study, the hydration of potato starch granules was investigated at the molecular level through various 1 H-> 13 C polarization transfer solid-state Nuclear Magnetic Resonance (ss-NMR) experiments. The impact of increasing the water content from 12.3 % to 45.9 % was assessed using 13 C Cross Polarization Magic Angle Spinning (CPMAS), Variable Contact Time (VCT-CPMAS), Variable Spin Lock (VSL-CPMAS), and T One Rho QUEnching (TORQUE) NMR sequences. Of these, VCT-CPMAS proved to be the most promising. When applied with an optimal number of contact times, it enabled the application of several mathematical models that provided detailed insights into the structuring of protons in the hydrated potato starch granules. At low hydration (12.3 %), the models enabled various structural domains to be distinguished, which we suggest are associated with helical and amorphous structures. At moderate hydration (45.9 %), we tested two fitting models. Two pools of protons were revealed, corresponding to loosely ordered structures on the scale of tens of nanometers. These findings suggest varying water distribution during starch hydration and are likely to indicate variable hydration levels in the multilamellar amorphous structures of starch granules., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Magnetic resonance microimaging (MRμI) is an outstanding technique for studying water transfers in millimetric bio-based materials in a non-destructive and non-invasive manner. However, depending on the composition of the material, monitoring and quantification of these transfers can be very complex, and hence reliable image processing and analysis tools are necessary. In this study, a combination of MRμI and multivariate curve resolution-alternating least squares (MCR-ALS) is proposed to monitor the water ingress into a potato starch extruded blend containing 20% glycerol that was shown to have interesting properties for biomedical, textile, and food applications. In this work, the main purpose of MCR is to provide spectral signatures and distribution maps of the components involved in the water uptake process that occurs over time with various kinetics. This approach allowed the description of the system evolution at a global (image) and a local (pixel) level, hence, permitted the resolution of two waterfronts, at two different times into the blend that could not be resolved by any other mathematical processing method usually used in magnetic resonance imaging (MRI). The results were supplemented by scanning electron microscopy (SEM) observations in order to interpret these two waterfronts in a biological and physico-chemical point of view., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Silvia Mas Garcia reports financial support was provided by French National Institute for Agricultural Research INRAE. Silvia Mas Garcia reports a relationship with French National Institute for Agricultural Research INRAE that includes: employment., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The aim of this study is to investigate the ability of Time-Domain Nuclear Magnetic Resonance (TD-NMR) combined with Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) analysis to detect changes in hydration properties of nineteen genotypes of Arabidopsis (Arabidopsis thaliana) seeds during the imbibition process. The Hybrid hard and Soft modelling version of MCR-ALS (HS-MCR) applied to raw TD-NMR data allowed the introduction of kinetic models to elucidate underlying biological mechanisms. The imbibition process of all investigated hydrated Arabidopsis seeds could be described with a kinetic model based on two consecutive first-order reactions related to an initial absorption of water from the bulk around the seed and a posteriori hydration of the internal seed tissues, respectively. Good data fit was achieved (LOF % = 0.98 and r 2 % = 99.9), indicating that the hypothesis of the selected kinetic model was correct. An interpretation of the mucilage characteristics of the studied Arabidopsis seeds was also provided. The presented methodology offers a novel and general strategy to describe in a comprehensive way the kinetic process of plant tissue hydration in a screening objective. This work also proves the potential of the MCR methods to analyse raw TD-NMR signals as alternative to the controversial and time-consuming pre-processing techniques of this kind of data, known to be an ill-conditioned and ill-posed problem., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this contribution, a selective overview of low field, time-domain NMR (TD-NMR) applications in the agriculture and agrifood sectors is presented. The first applications of commercial TD-NMR instruments were in food and agriculture domains. Many of these earlier methods have now been recognized as standard methods by several international agencies. Since 2000, several new applications have been developed, using state of the art instruments, new pulse sequences and new signal processing methods. TD-NMR is expected, in the coming years, to become even more important in quality control of fresh food and agricultural products, as well as for a wide range of food-processed products. TD-NMR systems provide excellent means to collect data relevant for use in the agricultural environment and the bioenergy industry. Data and information collected by TD-NMR systems thus may support decision makers in business and public organizations., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The transverse relaxation time (T 2 ), measured with Carr-Purcell-Meiboom-Gill (CPMG) sequence, has been widely used to obtain the direct dimension data in two-dimension time domain NMR (2D TD-NMR). In this paper we are demonstrating that Continuous Wave Free Precession sequence, with low flip angle (CWFP-T 1 ), can be an alternative to CPMG as direct detection dimension. CWFP-T 1 is a fast single shot sequence, like CPMG, and yields an exponential signal governed predominantly by the longitudinal (T 1 ) relaxation time. To obtain the correlations between T 1 and T 2 (T 1 -T 2 maps) we are proposing the use of CPMG-CWFP-T 1 pulse sequence. In this sequence CPMG encodes T 2 information (indirect dimension) that modulates the CWFP-T 1 (direct dimension) signal amplitudes. CPMG-CWFP-T 1 experiments were compared with classical 2D sequences such as Saturation-Recovery-CPMG (SR-CPMG) and Inversion-Recovery-CPMG (IR-CPMG) sequence and yields similar results in phantom sample. The experimental time for the 2D sequences, using single scan, shows that SR-CPMG ≤ CPMG-CWFP-T 1  < IR-CPMG. Experimental and simulated results demonstrated that 2D-CPMG-CWFP-T 1 maps have higher resolution in T 1 dimension than the techniques that uses CPMG as direct dimension. CPMG-CWFP-T 1 sequence was also applied to study beef samples, and 2D maps showed higher resolution in the two fat signals than the classical IR-CPMG method., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Inc. All rights reserved.)

When unilateral NMR is employed with large gradients (20 T/m), measurements of T 1 using standard sequences become affected by Brownian motion of spins, particularly in samples with long spin-lattice relaxation times T 1 (>2000 ms) and a large diffusion coefficient D (2*10 -6 mm 2 /ms). In light of this, a modified saturation sequence which we have called GAUSS-SR is proposed that allows direct measurement of both D and T 1 to be carried out subject to certain constraints. The evolution of M z magnetization is the main phenomenon to be modeled. The sequence is composed of three main parts: (i) a saturation train designed to render the M z profile in Gaussian form, (ii) a main delay where by the simultaneous effects of T 1 and D on this profile has been solved analytically and (iii) a detection train to ensure a good signal-to-noise ratio. An NMR-MOUSE was used to acquire the desired measurement through this sequence. By relying on the coherence of the longitudinal rather than the transverse magnetization component, the sequence successfully provides the long-limit value of the diffusion coefficient., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The applications of Magnetic Resonance micro-Imaging (MRμI) cover nowadays a wide range of fields. However few of them present quantitative measurements when the sample of interest changes over time or in case of a long acquisition time. In this domain, two challenges have to be overcome: the introduction of a phantom as a reference signal and the guarantee that this signal is stable over the experiment duration while some conditions such as temperature and/or the moisture are varied. The aim of the present study was to implement a dedicated experimental set-up to generate a virtual phantom (ViP) signal in a vertical-bore 11.7 T NMR spectrometer, equipped with a micro-imaging probe. This study shows that the generation of a micro-imaging-dedicated ViP (μ-ViP) signal is of great benefit for on-line quality control of the spectrometer performance during acquisition in the case of real-time experiments. Thus, μViP represents a step towards improvement of the magnetic resonance signal quantification in small samples., (Copyright © 2016 Elsevier Inc. All rights reserved.)

By acquiring the FID signal in two-dimensional TD-NMR spectroscopy, it is possible to characterize mixtures or complex samples composed of solid and liquid phases. We have developed a new sequence for this purpose, called IR-FID-CPMG, making it possible to correlate spin-lattice T1 and spin-spin T2 relaxation times, including both liquid and solid phases in samples. We demonstrate here the potential of a new algorithm for the 2D inverse Laplace transformation of IR-FID-CPMG data based on an adapted reconstruction of the maximum entropy method, combining the standard decreasing exponential decay function with an additional term drawn from Abragam's FID function. The results show that the proposed IR-FID-CPMG sequence and its related inversion model allow accurate characterization and quantification of both solid and liquid phases in multiphasic and compartmentalized systems. Moreover, it permits to distinguish between solid phases having different T1 relaxation times or to highlight cross-relaxation phenomena., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The impact of homogalacturonans deficiency on the cell wall porosity of Arabidopsis thaliana QUA1 mutant was investigated using NMR measurements of protons mobility interpreted in terms of pore size variations at nanometer and micrometer scales. Isolation and purification of wild type and mutant stems and calli cell walls permitted to exacerbate the putative impact of the mutation on cellulose-hemicelluloses assembly in highly and poorly organised cell walls, respectively. NMR relaxation measurements of water and exchangeable biopolymer protons and self-diffusion processes of polyethylene glycol in walls informed about the porosity network density and heterogeneity. The role of pectins and proteins as well as the growth status of the cells on the wall porosity regulation are discussed.

Highly crystalline amylose complexes with menthone (1) and linalool (2) were analysed by wide-angle X-ray diffraction and solid-state nuclear magnetic resonance (NMR). The complexes, after partial water desorption in a controlled atmosphere (aw=0.75), displayed a typical V-isopropanol structure, showing the presence of ligand inside or between the helices in the crystalline domains. Sequential washing of the powdered complexes with ethanol before and after desorption permitted probing the intra- and inter-helical inclusions. High resolution magic angle spinning (HRMAS) recordings were used to compare the chemical shifts of free and bound aroma which allowed a proposal that some hydrogen bonding is involved in the amylose complexing. Moreover, it showed that free aroma was completely removed by ethanol washing. Using cross polarization magic angle spinning (CPMAS) and X-ray scattering experiments, it was demonstrated that the V-isopropanol type was retained for linalool whatever the treatment used. On the contrary, the measurement shifts toward the V-6I amylose hydrate (V-h) type for menthone after ethanol washing before the desorption step, reflecting the disappearance of inter-helical associations between menthone and amylose. The stability of the complex prepared with linalool shows that this ligand is more strongly associated to amylose helices. The discrepancies observed in the chemical shifts attributed to carbons C1 and C4 in CPMAS spectra of V-isopropanol and V-h forms could be attributed either to a deformation of the single helix (with possible inclusion of the ligand inside) or to the presence of the ligand between helices (only water molecules are present in the V-h form).

The chemical structure and interactions of the cell wall polysaccharides from the red edible seaweed Palmaria palmata were studied by liquid-like magic-angle-spinning (MAS) and cross-polarization MAS (CPMAS) solid-state 13C NMR spectroscopy. The liquid-like MAS and CPMAS 13C NMR spectra of the rehydrated algal powder revealed the presence of beta-(1-->4)/beta-(1-->3)-linked D-xylan with chemical shifts close to those observed in the solution 13C NMR spectrum of the polysaccharide. Observation of mix-linked xylan in the liquid-like MAS 13C NMR spectrum indicated that part of this cell wall polysaccharide is loosely held in the alga. The CPMAS NMR spectrum of the dry algal powder alcohol insoluble residue (AIR) showed broad peaks most of which corresponded to the mix-linked xylan. Hydration of AIR induced a marked increase in the signal resolution also in the CPMAS NMR spectra together with a shift of the C-3 and C-4 signals of the (1-->3)- and (1-->4)-linked xylose, respectively. Such modifications were present in the spectrum of hydrated (1-->3)-linked xylan from the green seaweed Caulerpa taxifolia and absent in that of (1-->4)-linked xylan from P. palmata. This result emphasizes the important role of (1-->3) linkages on the mix-linked xylan hydration-induced conformational rearrangement. The mix-linked xylan signals were observed in the CPMAS NMR spectrum of hydrated residues obtained after extensive extractions by NaOH or strong chaotropic solutions indicating strong hydrogen bonds or covalent linkages. T(1 rho) relaxations were measured close or above 10 ms for the mix-linked xylan in the dry and hydrated state in AIR and indicated that the overall xylan chains likely remain rigid. Rehydration of the mix-linked xylan lead to a decrease in the motion of protons bounded to the C-1 and C-4 carbons of the (1-->4)-linked xylose supporting the re-organization of the xylan chains under hydration involving junction-zones held by hydrogen bonds between adjacent (1-->4)-linked xylose blocks. The CPMAS NMR spectrum of both dry and rehydrated residues obtained after NaOH and HCl extractions demonstrated the presence of cellulose and (1-->4)-linked xylans. The structures of the different polysaccharides are discussed in relation to their interactions and putative functions on the cell wall mechanical properties in P. palmata.

13C and 1H NMR spectra of an ethanol insoluble material (EIM) prepared from the pericarp of mature-green (MG) and red-ripe (RR) tomato fruits were acquired in 'liquid-like' and cross-polarisation with dipolar decoupling and magic angle spinning (CPMAS) conditions using the same triple resonance probe. Such a strategy allowed acquisitions of various NMR experiments aimed at detecting compositional differences as well as distinguishing differences in molecular mobility for various constituent polysaccharides related with the two ripening stages. Increase of the proton dipolar decoupling power levels from 3 to 50-55 kHz during single pulse 13C acquisition, led to more intense signals for pectic and hemicellulosic polysaccharides. This behaviour was interpreted as reflecting motional restrictions of these polysaccharides inside the porous cell wall network. Measurements of the proton rotating frame relaxation times T(1rho) in the 'liquid-like' conditions and of the proton transverse relaxation times T(2) from CPMAS spectra, revealed changes in mobilities for some pectic polysaccharides in relation with ripening, particularly for the H1 and H5 protons of alpha-1,5 arabinan (Ara) side chains of rhamnogalacturonans. These data are discussed in relation with known pectic modifications occurring during ripening and associated with the tomato fruit softening.