Search

Our study investigated the impacts of starch botanical origin (tapioca versus wheat starch) and gluten addition on the water distribution and hydrothermal changes of starch in model dough systems compared to their pure starch counterparts. In it, we employed a combination of time-domain nuclear magnetic resonance (TD-NMR), wide angle X-ray diffraction (WAXD), solid state nuclear magnetic resonance (ssNMR) at variable temperature (VT) and differential scanning calorimetry (DSC) measurements. The results showed that at intermediate hydration levels, water ingress into starch granules, increase in glucan chain mobility, and dissociation of double helices (DH) of amylopectin occurred at lower temperatures than crystallite loss of order and melting. The inhibitory effect of gluten on wheat starch hydrothermal changes was explained by a higher water adsorption capacity of gluten compared to starch at this hydration level (50%, wb). However this effect was shown to be influenced by starch botanical origin, tapioca-based systems showing no hindrance effect of gluten on starch-water interaction. The study also provides additional evidence for the sensitivity and detection scales of the different techniques at 50% water content. [Display omitted] • Combined VT TD-NMR, WAXD, ssNMR, DSC for effective analysis of dough hydrothermal changes. • Multi-scale investigation of heat-induced transformation of starch and gluten in model dough systems. • Multi-scale study to probe the inhibitory effect of gluten on starch hydrothermal changes in model dough systems. [ABSTRACT FROM AUTHOR]

To establish a "green" biorefinery extraction of apple pomace pectin, a sequential pretreatment with three natural deep eutectic solvents (NADES, choline chloride (CC): glycerol (G); CC: lactic acid (LA); potassium carbonate (K): G) was used prior to hot water extraction. A synergistic effect of CC:G and CC:LA pretreatments was observed and led to the highest recovery of pectin. The sequential NADES/water extraction process also provided a mean to tailor pectin main structure. It was explained as resulting from ion exchange and individual NADES components effects. The 13C solid state NMR T 1ρ H and T HH parameters indicated a reorganization of cellulose in the residues following extraction of pectin, notably after alkaline K:G pretreatment/water extraction. Hence, sequential NADES pretreatments/water extraction represents a "green" alternative to mild mineral acid to extract pectin and to tailor its main structures, while the residual pomace can be further sources of valuable compounds and polymers. • Sequential NADES and water extractions give high pectin yield from apple pomace. • Sequential NADES pretreatments offered a mean to tailor pectin structure. • NADES and polysaccharides interactions are proposed to loosen the cell wall. • Residual cellulose fiber was reorganized by removal of alkaline-soluble pectin. • Close pectin-cellulose interaction was proved by 1H → 13C polarization transfer kinetic. [ABSTRACT FROM AUTHOR]

• The viscoelastic mechanical properties of fresh and plasmolyzed apple are reported. • Damping (tan∂) and storage modulus (E') are related. • Plasmolyzed apples are better distinguished by the relation between tan∂ and E'. • Cell wall galactose and arabinose relation with E' distinguish two groups of apples. • Cellulose C4 NMR mobility is related with E': firm apples have disordered cellulose. The viscoelastic mechanical properties are important quality traits for fleshy fruit uses. The contribution of cell wall polysaccharides chemistry and organization on their variability was studied in six varieties of apple. Correlation between damping and storage modulus of plasmolyzed tissue distinguished better apple varieties on their viscoelasticity than fresh samples. Galactose, arabinose and uronic acids correlated positively with the storage modulus of fresh apple samples (E' f). These corresponded to 4-linked galactan but no specific arabinose linkage. Galacturonic acid branched on O-3 and terminal rhamnose correlated negatively with E' f. These correlations formed two groups of fruit except for branched methyl-esterified galacturonic. Solid-state 13C NMR spectroscopy analyses showed that E' f correlated negatively with cellulose C4 T 1 ρ H relaxation and positively with pectin methyl esters T H H proton diffusion. The results point to the key roles of pectin structure and hydration and cellulose microfibrils distribution on apple mechanical properties. [ABSTRACT FROM AUTHOR]

Different amounts of cellulose nanocrystals (CNCs) were added to glycerol-plasticized thermoplastic starch (TPS) to obtain bio-based nanocomposites. First, nanocomposites are prepared by extrusion and their structure is studied at different scales using WAXS (Wide Angle X-ray Scattering) and solid-state NMR (Nuclear Magnetic Resonance) for local/crystalline organization, AF4 (Asymmetrical Flow Field-Flow Fractionation) for molecular weight and chain length, and SEM (Scanning Electron Microscopy) for the morphology at a larger scale. Then, relevant mechanical properties and behavior in physiological conditions (swelling, enzymatic degradation) are characterized. The results show that the incorporation of cellulose nanocrystals up to 2.5 wt% causes a mechanical reinforcement as determined by DMTA (Dynamic Mechanical Thermal Analysis) and reduces the swelling and the enzymatic degradation of the materials compared to reference TPS. This could be linked to the formation of starch-cellulose hydrogen and hydroxyl bonds. Conversely, above 5 wt% CNC content nanocrystals seem to aggregate which in turn worsens the behavior in physiological conditions. [ABSTRACT FROM AUTHOR]

• Mannan-enriched extracts were obtained from wheat endosperm and characterized. • In wheat endosperm, mannan is made of short unsubstituted chains of mannose. • Despite its linear structure, wheat mannan is (partly) water soluble. • No interaction between wheat mannan and other cell wall components were detected. 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. [ABSTRACT FROM AUTHOR]

Flax (Linum usitatissimum L.) is a plant of industrial importance, its fibres being presently used for high-value textile applications, composite reinforcements as well as natural actuators. Human interest in this fibre-rich plant dates back several millennia, including to Ancient Egypt where flax was used extensively in various quotidian items. While the recent technical developments of flax fibres continue to diversify through scientific research, the historical use of flax also has rich lessons for today. Through careful examination of ancient Egyptian and modern flax fibres, this study aims to conduct a multi-scale characterization from the yarn to the fibre cell wall scale, linking differences in structure and polysaccharide content to the mechanical performance and durability of flax. Here, a multi-scale biochemical study is enriched by scanning electron microscopy and nanomechanical investigations. A key finding is the similarity of cellulose features, crystallinity index and local mechanical performances between ancient and modern fibres. Biochemically speaking, monosaccharides analysis, deep-UV and NMR investigations demonstrate that ancient fibres exhibit less pectins but a similar hemicellulosic content, especially through uronic acids and galactose, suggesting the sensitivity of these non-crystalline components. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, benchmarking of methods used for assessing freeze damage in potatoes was carried out. Initially, the samples were frozen by subjecting them to three different temperatures (i.e. at – 18 °C, − 30 °C, and at − 74 °C). Then, different analytical techniques comprising of focused methods (i.e. cryo-Scanning elctron microscopy-cryo-SEM, confocal laser scanning microscopy-CLSM) and global methods (i.e. texture analysis, low field nuclear magnetic resonance (NMR), exudate loss and colour change) were used to assess the impact of the freezing treatment from the different point of view addressed by each method. As a result, each of these methods were able to distinguish significantly fresh samples from the frozen-thawed samples. Focused methods like cryo-SEM and CLSM methods could differentiate the impact of all three different protocols. Meanwhile, texture analysis (including conventional method and novel method based on a touchless laser puff firmness tester), NMR and exudate loss could only determine the quality difference between − 18 °C and − 74 °C freezing conditions. Colour analysis was found as an inappropriate parameter for comparing the three freezing protocols. Among all analytical techniques, cryo-SEM provides the most authentic information about the product as the analysis is performed in frozen state, while for other techniques the product is thawed prior to analysis. • Benchmarking of methods for accessing freeze damage in potatoes was carried out. • Three different freezing protocols have been compared. • Focused methods could differentiate the impact of all different freezing protocols. • Texture, NMR and exudate loss had limitations to differentiate freezing conditions. [ABSTRACT FROM AUTHOR]

Highlights • The impact of field retting time was studied on six flax fibres samples. • AFM measurements revealed a significant increase of cell wall stiffness with retting. • XRD and NMR investigations showed an increase of cellulose crystallinity with retting. • NMR evidenced a compaction of inaccessible polymers for most retted sample. • This densification can be a possible explanation of the indentation modulus increase. Abstract 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. [ABSTRACT FROM AUTHOR]

• Apple firmness is not a general indicator of juice yield. • Cell-encapsulated water in the apple matrix is related to low juice yield. • Flesh mechanics distinguish apples according to their susceptibility to ice damage. • Cell wall cellulose ordering and pectin hydration determine apple firmness. • Cider apple juice yields rely on both genetics and development. 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. [ABSTRACT FROM AUTHOR]

Deciphering the determinants of starch digestion from multiple interrelated properties is a challenge that can benefit from multifactorial data analysis. The present study investigated the digestion kinetic parameters (rate, final extent) of size-fractions from four commercial wheat starches with different amylose contents. Each size-fraction was isolated and characterized comprehensively using a large range of analytic techniques (FACE, XRD, CP-MAS NMR, time-domain NMR, DSC...). A statistical clustering analysis applied on the results revealed that the mobility of water and starch protons measured by time-domain NMR was consistently related to the macromolecular composition of the glucan chains and to the ultrastructure of the granule. The final extent of starch digestion was determined by the granule structural features. The digestion rate coefficient dependencies, on the other hand, changed significantly with the range of granule size, i.e. the accessible surface for initial binding of α-amylase. The study particularly showed the molecular order and the chains mobility predominantly limiting or accelerating the digestion rate depending on the accessible surface. This result confirmed the need to differentiate between the surface and the inner-granule related mechanisms in starch digestion studies. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, the properties of cellulose (CE)/xyloglucan (XG) biopolymer blends are investigated, taking inspiration from the outstanding mechanical properties of plant cell walls. CE and XG were first co-solubilized in an ionic liquid, 1-ethyl-3-methylimidazolium acetate, in order to blend these biopolymers with a varying CE:XG ratio. The biopolymers were then regenerated together using water to produce solid blends in the form of films. Water-soluble XG persisted in the films following regeneration in water, indicating an attractive interaction between the CE and XG. The final CE:XG ratio of the blends was close to the initial value in solutions, further suggesting that intimate mixing takes place between CE and XG. The resulting CE/XG films were found to be free of ionic liquid, transparent and with no evidence of phase separation at the micron scale. The mechanical properties of the blend with a CE:XG ratio close to one revealed a synergistic effect for which a maximum in the elongation and stress at break was observed in combination with a high elastic modulus. Atomic force microscopy indicates a co-continuous nanostructure for this composition. It is proposed that the non-monotonous variation of the mechanical performance of the films with XG content is due to this observed nanostructuration. [ABSTRACT FROM AUTHOR]

Currently, the effects of global warming are one of the most important topics on the agendas of all governments and international economic and scientific organisations on the planet. Temperatures and rainfall will be especially subjected to increasing deregulation, and thus crop yields will be affected according to geographic location. Cellulosic materials, such as bast fibres, are considered one solution to decrease human environmental impact: they are a renewable resource, biodegradable and have a lower carbon emission than synthetic materials. However, their quality, yield and mechanical properties depend on environmental conditions during plant growth. In this paper, we explored the possible impact of seasonal drought linked to future climate change on flax plants and fibre quality. Two batches of the same textile flax plant cultivar were grown under two different field environmental conditions in the same year, one taken as a control under regular climatic conditions and the second one grown under drought stress. Carbon isotopic discrimination reveal an increase in water stress plant of the fibre δ 13C, reflecting that plants are indeed suffering from drought stress from a physiological point of view. We characterized the mechanical properties, biochemistry and morphology parameters at both the stem and technical fibre scales. Our results showed that the plants of the two batches were morphologically different and that the drought-stressed plants were smaller, mainly in terms of the height of the stem (−28%) and diameter (−16%). Biochemical analyses highlighted a contrasting lignin content between the two batches. A difference in protein content was also measured, with an increased amount in stressed flax plants, with contrasting distributions revealed by tyrosine and tryptophan monitored by synchrotron UV fluorescence. In addition, polysaccharide composition was also quantified with an increase in mannose and an important decrease in glucose in the drought-stressed technical fibres. Surprisingly, despite the difference in biochemistry composition and morphological parameters, the mechanical properties of elementary flax fibres extracted from the two batches were not significantly different. This suggests that drought can affect the yield and biochemistry of the extracted technical flax fibres but does not necessarily impact the longitudinal mechanical performance of single fibres. • The flax cell wall composition after drought do change markedly. • Synchrotron imaging shows contrasted protein and hydroxycinnamate in drought stem. • Drought affect the yield and biochemistry of the individual flax fibres. • Drought affect biochemistry but does not necessarily impact the tensile performances. [ABSTRACT FROM AUTHOR]

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. [Display omitted] [ABSTRACT FROM AUTHOR]

Heteroxylans (HX) from vitreous and floury parts of maize endosperm were isolated. Structural analysis showed a xylan backbone with few unsubstituted xylose residues (<9%) demonstrating the high content in side chains in both fractions. HX from floury endosperm contained more arabinose and galactose than vitreous HX. The mono-substitution rate was 15% higher in the vitreous endosperm HX. Similar amounts of uronic acids were present in both fractions (~7% DM). Galactose in the floury endosperm HX was present exclusively in terminal position. A xylanase preparation solubilized more material from floury (40.5%) than from vitreous endosperm cell walls (15%). This could be a consequence of the structural differences between the two fractions and/or of the impact of structure on the interaction abilities of these fractions with other cell wall polysaccharides. Our study advances the understanding of cell wall polysaccharides in maize endosperm and their role in enzymatic susceptibility of maize grain. • Heteroxylans (HX) from vitreous and floury endosperm of maize were characterized. • The floury endosperm contains more cell wall components than the vitreous one. • Vitreous HX contains 15% more mono-substituted xylose than floury HX. • Xylanases solubilized ~2.5 more matter from floury than from vitreous cell walls. • The results will allow improving the enzymatic preparations used in animal feeding. [ABSTRACT FROM AUTHOR]

The relationship between fruit and puree's characteristics is still poorly understood. In particular, it is not understood how pectin solubilisation and degradation alter the texture of plant-cell dispersions and how a targeted application of processing conditions can be used to design naturally textured food products. Systematic combinations of thermal and mechanical treatments with three different temperatures (70, 83, 95 °C) and grinding speeds (300, 1000, 3000 rpm), applied on one-month (T1) and six-months stored (T6) apples, were used to generate apple purees with contrasted structural and textural characteristics. For T1, serum viscosity increased with increasing temperature (8–104 mPa.s) with a marked increase in pectin solubilisation (1–6 mg/g serum). Pectin macromolecular size and (arabinose + galactose)/rhamnose ratio, estimating pectin side chain branching, decreased with temperature. For T6, pectin showed decreased galactose, leading to facilitated cell separation, low serum viscosity (~16 mPa.s) and restricted impact of process conditions on pectin composition and structure. Grinding had limited impact on pectin solubilisation for T1 and T6 but strongly impacted particle size (498–1096 μm for T1 or 320–1068 μm for T6) and puree's viscosity (871–1475 mPa.s for T1 or 853–1453 mPa.s for T6). Tissue fragmentation was favoured by temperature increase for T1 and by the maturation of raw apples. Process parameters induced differences in the puree's structure and texture depending on the maturation level of raw apples. The observed changes were linked to pectin degradation and substantial side chain loss. [Display omitted] • Elevated temperature and apple maturation induced pectin degradation. • Pectin degradation and solubilisation enhanced cell separation during processing. • The interaction storage duration × temperature had a major impact on pectins. • Mechanical processes altered pectin composition and structure only slightly. • Mechanical treatments highly affected puree's texture but not serum viscosity. [ABSTRACT FROM AUTHOR]

[Display omitted] • High yield extraction of hydroxy-fatty acids from agro-industrial byproducts. • Bioinspired polyesters are formed by co-polymerization of fatty acid and glycerol. • Tuning the level of esterified glycerol modifies the polymer's structure. • Resulting in modified elastomer's mechanical properties (up to 200 % elongation). • With significant impact on O 2 permeability and anti-biofouling properties. By mimicking the cutin natural polyester networks of plant cuticles, we produced hydrophobic elastomers by a sustainable process, i.e., using a catalyst- and solvent-free polycondensation of glycerol and hydroxy fatty acids, two by-products of the agro-food industry. The hydroxy fatty acid fraction was obtained by ethanolic alkaline hydrolysis of cuticle from industrial tomato. This industrial-like fatty acid fraction contained more than 90 wt%. of 9(10),16 dihydroxyhexadecanoic acid (diOHC16). The co-polyesters were designed by increasing the ratio of esterified glycerol/diOHC16 in a range observed in plant cutins (up to 6 wt%). Their structure and functional properties (thermal, mechanical, gas permeability, interaction with bacterial cells) were characterized. Increasing the glycerol contents induced a significant decrease in the crosslink density of the polyesters and the formation of crystalline domains with a hexagonal organization. These structural modifications were related to a marked increase of elastomeric extensibility (up to 217 %). While water vapor permeability was not impacted, the increase of glycerol content induced a significant decrease in oxygen permeability. None of the polyesters displayed biocide activity, but an increase of glycerol content significantly reduced the adhesion of bacterial cells, potentially giving rise to antifouling applications. [ABSTRACT FROM AUTHOR]

• A novel double dielectric barrier discharge plasma reactor with a liquid interface has been designed. • It is possible to totally convert inulin into 100 % fructose and glucose. • No degradation products are generated. • Combined analytical results evidenced the acidic attack of the glycosidic bond leading to depolymerization. We report the complete conversion of inulin in gas/liquid media by a dielectric barrier discharge plasma at atmospheric pressure. Depending on the plasma treatment time (from 1 to 30 min) and the chemical nature of the gases (air, oxygen, nitrogen), it was possible to depolymerize inulin into fructo-oligosaccharides with a degree of polymerization under 5 or to achieve a total conversion of inulin into its two monomeric constituents, fructose and glucose in 20 min, without any degradation products. Combined results from liquid chromatography (HPLC), solid state Nuclear Magnetic Resonance (ssNMR) and mass spectroscopy revealed that the breakage of the β 1-4-bridged oxygen occurs by an acidic attack, following the oxidation of the polymer. Infrared spectroscopy revealed the oxidation and breakage of the polymer and also adsorption of nitrate species. Non thermal plasma treatment appears as a promising technology for the efficient production of mono and oligosaccharides from various sources for the added value molecules in food and pharmaceutical application domains. [ABSTRACT FROM AUTHOR]