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The soft flesh problem is associated with an early loss of rigor within 24 hrs after slaughtering. The results obtained in the investigation of the slaughtering procedure on the progress of rigor and the tissue structure modification, conducted with the help of magnetic resonance imaging, are discussed.

The aim of this study was to determine whether exogenous glucose metabolism influences the pH in superfused EDL muscle from growing rats fed or starved for 48 h (body weight 55 and 45 g, respectively). Energy state and intracellular pH of muscle were repeatedly monitored by 31P-nuclear magnetic resonance spectroscopy (31P-NMRS); glycogen and other energy metabolites were assayed enzymatically in muscle extracts at the end of the experiment. In EDL muscles from starved rats superfused with glucose for 4 h, intracellular pH was elevated (7-7.3), lactate concentration low, glycogen repletion very intense and citrate synthase activity high. We conclude that glucose was routed mainly toward both oxidative phosphorylation and glycogen synthesis in EDL muscles after food deprivation of rats. In contrast, the major pathway in muscles from fed rats may be glycolysis because the glycogen pool remained constant throughout the experiment. The additional and minor pH component (in the range of 6.5 to 6.8) seen in muscles from fed rats, even in the presence of exogenous glucose, might be due to impaired glucose utilization because this component appears also in muscles from starved rats superfused without glucose or with a nonmetabolizable analog of glucose. Consequently, direct pH measurement by 31P-NMR may be considered to be a precise criterion for evaluation of differences in metabolic potentialities of muscle studied ex vivo in relation to the nutritional state of rats. [ABSTRACT FROM AUTHOR]

To investigate the incubation conditions encountered by enzymes in cereal-based product transformation processes, this study aims to provide comprehensive information on the effect of low (18 %) to high (72 %) solid loading on the behavior of bacterial and fungal xylanases towards wheat grain fractions, i.e. white flour, ground whole grain and bran. Both enzymes are effective from 30 % water content. A water content of 50 % appears as the threshold for optimal arabinoxylan solubilisation. The specificity of enzymes was influenced by low hydration conditions, particularly in wheat bran, which contains arabinoxylan with diverse structures. Especially the bacterial xylanase became more tolerant to arabinose substitution as the water content decreased. Time Domain-NMR measurements revealed four water mobility domains in all the fractions. The water populations corresponding to 7.5 nm to 15 nm pores were found to be the most restrictive for enzyme activity. These results define the water content limits for the optimal xylanase action in cereal products., 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 © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Apple cider juice yield at harvest and after 15 and 30 days of storage durations was studied by analyzing the mechanical properties of fresh and plasmolyzed flesh, water distribution, cell wall polysaccharide composition and organization of the apples; in this study, the apple varieties used were Avrolles, Douce coetligne, Douce moen, Judor, Petit jaune. Juice yield mainly depended on the apple variety and the storage duration. Cellulose organization and cell wall pectin hydration were affected by ripening and are related to fruit firmness. Flesh viscoelastic mechanical properties were not general indications of juice yields. However, these properties helped distinguish the varieties according to flesh damage caused by ice crystals upon freezing. Cell encapsulation of the juice in the flesh contributed to lower yields. The apple variety and harvesting mode are recommended as a means to better control juice yield variations., 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 © 2023 Elsevier Ltd. All rights reserved.)

This work aimed to establish the relationships between flour components, dough behaviour and changes in water distribution at mixing. TD NMR was used to track water distribution in dough during mixing for different mixing times and hydration levels. Four commercial wheat flours with distinct characteristics were expressly selected to exhibit various dough behaviours at mixing. TD NMR measurements of mixed dough samples revealed four to five water mobility domains depending on the flour type and the mixing modality. A classification tree procedure was used to identify characteristic patterns of water mobility in dough, called hydration states (HS). The HS changes with experimental conditions are highly dependent on flour characteristics, and HS were assigned to physical/chemical changes in the gluten network during dough formation. This study proposes an interpretation of the water distribution in dough based on gluten network development. This will help to adapt the mixing process to the flour characteristics., 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 © 2022 Elsevier Ltd. All rights reserved.)

This study was to investigate the distribution of water and arabinoxylan structures in growing wheat grain using two complementary imaging techniques, magnetic resonance microimaging (μMRI) and mass spectrometry imaging (MSI). μMRI showed an inhomogeneous water distribution, particularly at early stages. This heterogeneity revealed histological differences that corresponded, within the limits of resolution of μMRI, to tissues with specific physiological functions, including the vascular bundles, the cavity and the endosperm periphery. All of these tissues had a higher water content than the central endosperm. MSI revealed distinct xylan structures in these regions with high levels of Araf substitution around the cavity and acetylated xylans concentrated at the endosperm periphery. For the first time, acetylation and Araf substitution of arabinoxylans were found by image processing to spatially correlate with water distribution in planta. Acetylation and Araf substitution of xylans, which alter chain-chain interactions and increase wall porosity, decreased as the grain matured., (Copyright © 2022. Published by Elsevier Ltd.)

Fibre bundles are groups of elementary fibres glued together thanks to the middle lamella, and are the main fraction in plant fibre composites. In this study, relationship between the mechanical properties of flax fibre bundles, chemical composition and cellulose structure were investigated. To do so, a sequential biopolymer extraction was implemented. Fibre bundles were first depectinated by oxalate extraction, and then the hemicelluloses were extracted by LiCl/dimethyl sulfoxide (DMSO) and KOH. The oxalate extract consisted of homogalacturonans and type I rhamnogalacturonans, while the LiCl extract was composed mainly of glucomannans and the KOH extract of xyloglucans. The KOH stage resulted in the appearance of cellulose II in flax bundles. The extraction of pectin and hemicelluloses led to the disappearance of the middle lamella concomitant with a decrease in the tensile Young's modulus and maximum strength. Finally, the fibre bundle composition, ultrastructure and mechanical properties are discussed together in view of the thin middle lamella., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Biomass recalcitrance is governed by various molecular and structural factors but the interplay between these multiscale factors remains unclear. In this study, hot water pretreatment (HWP) was applied to maize stem internodes to highlight the impact of the ultrastructure of the polymers and their interactions on the accessibility and recalcitrance of the lignocellulosic biomass. The impact of HWP was analysed at different scales, from the polymer ultrastructure or water mobility to the cell wall organisation by combining complementary compositional, spectral and NMR analyses., Results: HWP increased the kinetics and yield of saccharification. Chemical characterisation showed that HWP altered cell wall composition with a loss of hemicelluloses (up to 45% in the 40-min HWP) and of ferulic acid cross-linking associated with lignin enrichment. The lignin structure was also altered (up to 35% reduction in β-O-4 bonds), associated with slight depolymerisation/repolymerisation depending on the length of treatment. The increase in [Formula: see text], [Formula: see text] and specific surface area (SSA) showed that the cellulose environment was looser after pretreatment. These changes were linked to the increased accessibility of more constrained water to the cellulose in the 5-15 nm pore size range., Conclusion: The loss of hemicelluloses and changes in polymer structural features caused by HWP led to reorganisation of the lignocellulose matrix. These modifications increased the SSA and redistributed the water thereby increasing the accessibility of cellulases and enhancing hydrolysis. Interestingly, lignin content did not have a negative impact on enzymatic hydrolysis but a higher lignin condensed state appeared to promote saccharification. The environment and organisation of lignin is thus more important than its concentration in explaining cellulose accessibility. Elucidating the interactions between polymers is the key to understanding LB recalcitrance and to identifying the best severity conditions to optimise HWP in sustainable biorefineries., (© 2021. The Author(s).)

Cereal grains provide a substantial part of the calories for humans and animals. The main quality determinants of grains are polysaccharides (mainly starch but also dietary fibers such as arabinoxylans, mixed-linkage glucans) and proteins synthesized and accumulated during grain development in a specialized storage tissue: the endosperm. In this study, the composition of a structure localized at the interface of the vascular tissues of the maternal plant and the seed endosperm was investigated. This structure is contained in the endosperm cavity where water and nutrients are transferred to support grain filling. While studying the wheat grain development, the cavity content was found to autofluoresce under UV light excitation. Combining multispectral analysis, Fourier-Transform infrared spectroscopy, immunolabeling and laser-dissection coupled with wet chemistry, we identified in the cavity arabinoxylans and hydroxycinnamic acids. The cavity content forms a "gel" in the developing grain, which persists in dry mature grain and during subsequent imbibition. Microscopic magnetic resonance imaging revealed that the gel is highly hydrated. Our results suggest that arabinoxylans are synthesized by the nucellar epidermis, released in the cavity where they form a highly hydrated gel which might contribute to regulate grain hydration., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Pectin plays a role in the recalcitrance of plant biomass by affecting the accessibility of other cell wall components to enzymatic degradation. Elimination of pectin consequently has a positive impact on the saccharification of pectin-rich biomass. This work thus focused on the behaviour of different pectin-degrading enzymes in the presence of low (5%) to high (35%) solid loading of lemon peel., Results: High solid loading of lemon peel affected pectin solubilisation differently depending on the pectinase used. Pectin lyase was less sensitive to a reduction of water content than was a mixture of endopolygalacturonase and pectin methylesterase, regardless of whether or not the latter's mode of action is processive or not. Marked changes in water mobility were observed along with enzymatic degradation depending on the enzyme used. However, the pectin lyase resulted in less pronounced shifts in water distribution than polygalacturonase-pectin methylesterase mixtures. At similar pectin concentration, pectin solutions hindered the diffusion of hydrolases more than the solid substrate. This can be attributed to the high viscosity of the highly concentrated pectin solutions while the solid substrate may provide continuous diffusion paths through pores., Conclusions: The increase in solid substrate loading reduced the efficiency of pectin-degrading enzymes catalysing hydrolysis more significantly than those catalysing β-elimination. LF-NMR experiments highlighted the impact of solid loading on water mobility. Compared to other enzymes and whatever the solid loading, pectin lyase led to longer relaxation times linked with the most destructuration of the solid substrate. This new information could benefit the biorefinery processing of pectin-rich plant material when enzymes are used in the treatment.

Background: Mass spectrometry imaging (MSI) is a family of acquisition techniques producing images of the distribution of molecules in a sample, without any prior tagging of the molecules. This makes it a very interesting technique for exploratory research. However, the images are difficult to analyze because the enclosed data has high dimensionality, and their content does not necessarily reflect the shape of the object of interest. Conversely, magnetic resonance imaging (MRI) scans reflect the anatomy of the tissue. MRI also provides complementary information to MSI, such as the content and distribution of water., Results: We propose a new workflow to merge the information from 2D MALDI-MSI and MRI images. Our workflow can be applied to large MSI datasets in a limited amount of time. Moreover, the workflow is fully automated and based on deterministic methods which ensures the reproducibility of the results. Our methods were evaluated and compared with state-of-the-art methods. Results show that the images are combined precisely and in a time-efficient manner., Conclusion: Our workflow reveals molecules which co-localize with water in biological images. It can be applied on any MSI and MRI datasets which satisfy a few conditions: same regions of the shape enclosed in the images and similar intensity distributions.

Background: The recalcitrance of lignocellulosics to enzymatic saccharification has been related to many factors, including the tissue and molecular heterogeneity of the plant particles. The role of tissue heterogeneity generally assessed from plant sections is not easy to study on a large scale. In the present work, dry fractionation of ground maize shoot was performed to obtain particle fractions enriched in a specific tissue. The degradation profiles of the fractions were compared considering physical changes in addition to chemical conversion., Results: Coarse, medium and fine fractions were produced using a dry process followed by an electrostatic separation. The physical and chemical characteristics of the fractions varied, suggesting enrichment in tissue from leaves, pith or rind. The fractions were subjected to enzymatic hydrolysis in a torus reactor designed for real-time monitoring of the number and size of the particles. Saccharification efficiency was monitored by analyzing the sugar release at different times. The lowest and highest saccharification yields were measured in the coarse and fine fractions, respectively, and these yields paralleled the reduction in the size and number of particles. The behavior of the positively- and negatively-charged particles of medium-size fractions was contrasted. Although the amount of sugar release was similar, the changes in particle size and number differed during enzymatic degradation. The reduction in the number of particles proceeded faster than that of particle size, suggesting that degradable particles were degraded to the point of disappearance with no significant erosion or fragmentation. Considering all fractions, the saccharification yield was positively correlated with the amount of water associated with [5-15 nm] pore size range at 67% moisture content while the reduction in the number of particles was inversely correlated with the amount of lignin., Conclusion: Real-time monitoring of sugar release and changes in the number and size of the particles clearly evidenced different degradation patterns for fractions of maize shoot that could be related to tissue heterogeneity in the plant. The biorefinery process could benefit from the addition of a sorting stage to optimise the flow of biomass materials and take better advantage of the heterogeneity of the biomass.

In wheat endosperm, mannan, is poorly documented. Nevertheless, this hemicellulosic polysaccharide might have a determinant role in wheat grain development since, in Arabidopsis thaliana, mutants with a reduced amount of mannan show an altered seed development. In order to gain knowledge about mannan in wheat, we have determined its biochemical structure in wheat endosperm where mannose content is about 0.2% (dry weight basis). We developed a method of enzymatic fingerprinting and isolated mannan-enriched fractions to decipher its fine structure. Although it is widely accepted that the class of mannan present in grass cell walls is glucomannan, our data indicate that, in wheat endosperm, this hemicellulose is only represented by short unsubstituted chains of 1,4 linked D-mannose residues and is slightly acetylated. Our study provides information regarding the interactions of mannan with other cell wall components and help to progress towards the understanding of monocot cell wall architecture and the mannan synthesis in wheat endosperm., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Flax retting is a major bioprocess in the cultivation and extraction cycle of flax fibres. The aim of the present study is to improve the understanding of the evolution of fibre properties and ultrastructure caused by this process at the plant cell wall scale. Initially, investigations of the mechanical performances of the flax cell walls by Atomic Force Microscopy (AFM) in Peak Force mode revealed a significant increase (+33%) in the cell wall indentation modulus with retting time. Two complementary structural studies are presented here, namely using X-Ray Diffraction (XRD) and solid state Nuclear Magnetic Resonance (NMR). An estimation of the cellulose crystallinity index by XRD measurements, confirmed by NMR, shows an increase of 8% in crystallinity with retting mainly due to the disappearance of amorphous polymer. In addition, NMR investigations show a compaction of inaccessible cell wall polymers, combined with an increase in the relaxation times of the C4 carbon. This densification provides a structural explanation for the observed improvement in mechanical performance of the secondary wall of flax fibres during the field retting process., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Relations between the apple cortex viscoelastic properties, water dynamics, histological, and chemical characteristics were investigated. Water mobility in four apple genotypes was studied by low-field NMR relaxometry prior and after plasmolysis of the cortex tissue. A discrete and a continuous method for decomposing the multi-exponential T 2 curves were implemented and compared. The results show that both methods of relaxation curve decomposition had close ability to discriminate genotypes before and after plasmolysis. Although the sensitivity of T 2 relaxometry allowed distinguishing microstructures among genotypes even after cellular fluids were mixed and diffused in plasmolyzed tissues, no relaxation component correlated with apple viscoelasticiy. Galactose and arabinose cell wall content were correlated with the storage modulus (E') prior and after plasmolysis though the correlation signs were opposite and pointed to a potential key role of pectin RGI side chains in regulating apple texture in turgid tissue., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Biomass recalcitrance to enzymatic hydrolysis has been assigned to several structural and chemical factors. However, their relative importance remains challenging to evaluate. Three representative biomass species (wheat straw, poplar and miscanthus) were submitted to four standard pretreatments (dilute acid, hot water, ionic liquid and sodium chlorite) in order to generate a set of contrasted samples. A large array of techniques, including wet chemistry analysis, porosity measurements using NMR spectroscopy, electron and fluorescence microscopy, were used in order to determine possible generic factors of biomass recalcitrance., Results: The pretreatment conditions selected allowed obtaining samples displaying different susceptibility to enzymatic hydrolysis (from 3 up to 98% of the initial glucose content released after 96 h of saccharification). Generic correlation coefficients were calculated between the measured chemical and structural features and the final saccharification rates. Increases in porosity displayed overall strong positive correlations with saccharification efficiency, but different porosity ranges were concerned depending on the considered biomass. Lignin-related factors displayed highly negative coefficients for all biomasses. Lignin content, which is likely involved in the correlations observed for porosity, was less detrimental to enzymatic hydrolysis than lignin composition. Lignin influence was highlighted by the strong negative correlation with fluorescence intensity which mainly originates from monolignols in mature tissues., Conclusions: Our results provide a better understanding of the factors responsible for biomass recalcitrance that can reasonably be considered as generic. The correlations with specific porosity ranges are biomass species-dependent, meaning that enzymes cocktails with fitted enzyme size are likely to be needed to optimise saccharification depending on the biomass origin. Lignin composition, which probably influences its structure, is the most important parameter to overcome to enhance enzymes access to the polysaccharides. Accordingly, fluorescence intensity was found to be a rapid and simple method to assess recalcitrance after pretreatment.

Lytic polysaccharide monooxygenases (LPMOs) are a class of powerful oxidative enzymes that breakdown recalcitrant polysaccharides such as cellulose. Here we investigate the action of LPMOs on cellulose fibers. After enzymatic treatment and dispersion, LPMO-treated fibers show intense fibrillation. Cellulose structure modifications visualized at different scales indicate that LPMO creates nicking points that trigger the disintegration of the cellulose fibrillar structure with rupture of chains and release of elementary nanofibrils. Investigation of LPMO action using solid-state NMR provides direct evidence of modification of accessible and inaccessible surfaces surrounding the crystalline core of the fibrils. The chains breakage likely induces modifications of the cellulose network and weakens fibers cohesion promoting their disruption. Besides the formation of new initiation sites for conventional cellulases, this work provides the first evidence of the direct oxidative action of LPMOs with the mechanical weakening of the cellulose ultrastructure. LPMOs can be viewed as promising biocatalysts for enzymatic modification or degradation of cellulose fibers.