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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.)

Solid-state NMR (ssNMR) is a unique technique allowing the study of macromolecular assemblies in their native state without prior modification. The proposed method simplifies the current long and tedious data-acquisition and processing protocols for Variable Contact Time (VCT) ssNMR experiments used in dynamic studies of macromolecular assemblies. Using cellulose nanocrystals as a model for polysaccharide assembly, the acquisition time was reduced by decreasing the number of scans and shortening the recycling time required for the 1 H to 13 C polarization transfers.•A tenfold reduction in the acquisition time for each kinetic point was achieved while maintaining a good signal to noise ratio.•The processing time for the pseudo-2D solid-state NMR data was also shortened by using signal intensities derived from peak picking rather than the classically-used spectral deconvolution method.•These optimizations enabled the molecular dynamic parameters T 1ρ H , T HH , T CH to be accessed within a day., Competing Interests: 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., (© 2022 The Author(s).)

A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample., (© 2022 John Wiley & Sons, Ltd.)

To provide evidence for previously proposed assumptions concerning starch gelatinization sub-mechanisms, a more detailed investigation was carried out using multiscale analysis of a starch type selected for its marked difference. Tapioca starch was chosen due to its cohesive/springy properties and its growing use in the food industry. Time-domain nuclear magnetic resonance (TD-NMR) was used to investigate the leaching of material, water absorption and crystallite melting in hydrated tapioca starch (45%). The interpretation of T2 mass intensity evolutions, especially those of the (intra- and extra-granular) aqueous phases, was discussed drawing on complementary techniques such as microscopy, Rapid Visco Analyser (RVA), differential scanning calorimetry (DSC) and swelling factor (SF) and solubility index (SI) measurements. Results show that the T2 assignments usually proposed in the literature are dependent on starch origin. The differences in T2 evolutions (value and mass intensity) observed between wheat and tapioca starches at intermediate hydration levels could be linked to the different gelatinization behaviour of tapioca starch involving the latter's higher granule rupture level, higher gelatinization temperature and greater swelling power above its gelatinization temperature., (© 2022 John Wiley & Sons, Ltd.)

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.)

The seeds of Arabidopsis thaliana become encapsulated by a layer of mucilage when imbibed. This polysaccharide-rich hydrogel is constituted of two layers, an outer layer that can be easily extracted with water and an inner layer that must be examined in situ in order to study its properties and structure in a non-destructive manner or disintegrated through hydrolysis or physical means in order to analyze its constituents. Mucilage production is an adaptive trait and we have exploited 19 natural accessions previously found to have atypical and varied outer mucilage characteristics. A detailed study using biochemical, histological and Time-Domain NMR analyses has been used to generate three related datasets covering 33 traits measured in four biological replicates. This data will be a rich resource for genetic, biochemical, structural and functional analyses investigating mucilage constituent polysaccharides or their role as adaptive traits.

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.)

This research aimed to study the effects of using a partial vacuum for bread baking on macromolecules and water distribution in gluten-free bread. Bread baking under partial vacuum results in greater oven rise and a larger gas fraction in the crumb. Because water's boiling point decreases under reduced pressure, it was expected that its distribution within the dough and its interactions with the others dough's constituents (mainly starch) would differ from those in bread baked under atmospheric pressure. Time-domain nuclear magnetic resonance was used, as it has the rare capacity to quantify both gelatinization and retrogradation of starch. Complementary rheological measurements made it possible to show that crumb Young's modulus was mostly influenced by the gas fraction whereas there was little change in starch gelatinization and retrogradation when dough was baked under partial vacuum. When insufficiently hydrated (48%), the volume of breads was practically the same whatever the baking process. Meanwhile, the nuclear magnetic resonance results suggested that amylose short-term crystallization (on cooling) is dependent on water content. In addition, crumb Young's modulus during storage at room temperature correlated with an increase in free induction decay signal intensity., (© 2019 John Wiley & Sons, Ltd.)

The traditional way to enhance signal-to-noise ratio (SNR) of nuclear magnetic resonance (NMR) signals is to increase the number of scans. However, this procedure increases the measuring time that can be prohibitive for some applications. Therefore, we have tested the use of several post-acquisition digital filters to enhance SNR up to one order of magnitude in time domain NMR (TD-NMR) relaxation measurements. The procedures were studied using continuous wave free precession (CWFP-T 1 ) signals, acquired with very low flip angles that contain six times more noise than the Carr-Purcell-Meiboom-Gill (CPMG) signal of the same sample and experimental time. Linear (LI) and logarithmic (LO) data compression, low-pass infinity impulse response (LP), Savitzky-Golay (SG), and wavelet transform (WA) post-acquisition filters enhanced the SNR of the CWFP-T 1 signals by at least six times. The best filters were LO, SG, and WA that have high enhancement in SNR without significant distortions in the ILT relaxation distribution data. Therefore, it was demonstrated that these post-acquisition digital filters could be a useful way to denoise CWFP-T 1 , as well as CPMG noisy signals, and consequently reducing the experimental time. It was also demonstrated that filtered CWFP-T 1 method has the potential to be a rapid and nondestructive method to measure fat content in beef and certainly in other meat samples., (© 2018 John Wiley & Sons, Ltd.)

In foodstuffs, physico-chemical interactions and/or physical constraints between spores, inhibitors and food components may exist. Thus, the objective of this study was to investigate such interactions using a model emulsion as a microbial medium in order to improve bacterial spore control with better knowledge of the interactions in the formulation. Emulsions were prepared with hexadecane mixed with nutrient broth using sonication and were stabilized by Tween 80 and Span 80. The hexadecane ratio was either 35% (v/v) or 50% (v/v) and each emulsion was studied in the presence of organic acid (acetic, lactic or hexanoic) at two pH levels (5.5 and 6). Self-diffusion coefficients of emulsion components and the organic acids were measured by Pulsed Field Gradient-Nuclear Magnetic Resonance (PFG-NMR). The inhibition effect on the spore germination and cell growth of Bacillus weihenstephanensis KBAB4 was characterized by the measure of the probability of growth using the most probable number methodology, and the measure of the time taken for the cells to germinate and grow using a single cell Bioscreen® method and using flow cytometry. The inhibition of spore germination and growth in the model emulsion depended on the dispersed phase volume fraction and the pH value. The effect of the dispersed phase volume fraction was due to a combination of (i) the lipophilicity of the biocide, hexanoic acid, that may have had an impact on the distribution of organic acid between hexadecane and the aqueous phases and (ii) the antimicrobial activity of the emulsifier Tween 80 detected at the acidic pH value. The interface phenomena seemed to have a major influence. Future work will focus on the exploration of these phenomena at the interface., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The behavior upon immersion in water of two types of starchy materials of biomedical relevance, amorphous potato starch and glycerol-plasticized potato starch, is analyzed in depth. Synchrotron X-ray scattering, specifically wide-angle X-ray scattering (WAXS), and magnetic resonance microimaging (MRμI) are used as very precise and nondestructive quantitative methods to monitor water transfers and structure changes in the samples, with refined spatial and kinetics results. The ingress of water in the cylinder-shaped samples can be inferred from both techniques, and from this, a diffusion mechanism is deduced for each sample type. Qualitatively, scattering and imaging give comparable results: plasticized samples are shown to behave close to a Fickian diffusion case, amorphous samples close to a case II. WAXS results also provide an in-depth knowledge of the crystalline structures associated to each step of the water ingress, and these are in turn correlated to water diffusion. To refine these observations, a recrystallized starch sample is also analyzed via WAXS. This study gives better insight into the structure of a material with a huge biomedical potential (as implants, for example), and for such applications, the behavior upon immersion in water is particularly relevant.

Composite films made with Arabinoxylans (AXs) (with high, middle and low level of substitution by arabinose) and (1 → 3)(1 → 4)-β-D-glucans (BGs) extracted from cereal cell walls have been prepared and analyzed using microscopy (SEM and LSCFM), DSC, mechanical tests and TD-NMR spectroscopy. The objectives were to correlate molecular and physico-chemical properties of films with mechanical and hydration properties of wheat cell walls. A phase separation phenomenon was observed for films made with highly substituted AXs and BGs at a ratio AX/BG of 60/40. This phase separation was correlated with lower dipolar interactions between polysaccharide chains and a decrease of ultimate strain and stress of films. Highly substituted AX and BG composite films exhibited very weak mechanical properties in agreement with weaker interactions between the polymer chains. This effect was supported by NMR results showing that interactions between AXs and BGs decreased with increased substitution of AXs in composite films. Lower dipolar interactions between polysaccharides favored the water mobility in relation with a higher specific surface area of polysaccharides in films but also higher distances between polysaccharide chains so larger nanopores in composite films made within highly substituted AXs. These multiscale characterizations agreed with the structural changes observed in wheat grain during its development., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The dynamics of rigid dendrimer and flexible PEG probes in sodium caseinate dispersions and acid gels, including both translational diffusion and rotational diffusion, were studied by NMR. Above the onset of the close-packing limit (C ∼ 10 g/100 g H2 O), translational diffusion of the probe depended on its flexibility and on the fluctuations of the matrix chains. The PEG probe diffused more rapidly than the spherical dendrimer probe of corresponding hydrodynamic radius. The greater conformational flexibility of PEG facilitated its motion through the crowded casein matrix. Rotational diffusion was, however, substantially less hindered than the translational diffusion and depended on the local protein-probe friction which became high when the casein concentration increased. The coagulation of the matrix led to the formation of large voids, which resulted in an increase in the translational diffusion of the probes, whereas the rotational diffusion of the probes was retarded in the gel, which could be attributed to the immobilized environment surrounding the probe. Quantitative information from PFG-NMR and SEM micrographs have been combined for characterizing microstructural details in SC acid gels., (© 2014 Wiley Periodicals, Inc.)

Arabidopsis seeds rapidly release hydrophilic polysaccharides from the seed coat on imbibition. These form a heavy mucilage layer around the seed that makes it sink in water. Fourteen natural Arabidopsis variants from central Asia and Scandinavia were identified with seeds that have modified mucilage release and float. Four of these have a novel mucilage phenotype with almost none of the released mucilage adhering to the seed and the absence of cellulose microfibrils. Mucilage release was modified in the variants by ten independent causal mutations in four different loci. Seven distinct mutations affected one locus, coding the MUM2 β-D-galactosidase, and represent a striking example of allelic heterogeneity. The modification of mucilage release has thus evolved a number of times independently in two restricted geographical zones. All the natural mutants identified still accumulated mucilage polysaccharides in seed coat epidermal cells. Using nuclear magnetic resonance (NMR) relaxometry their production and retention was shown to reduce water mobility into internal seed tissues during imbibition, which would help to maintain seed buoyancy. Surprisingly, despite released mucilage being an excellent hydrogel it did not increase the rate of water uptake by internal seed tissues and is more likely to play a role in retaining water around the seed.