The study focuses on hydration during immersion of extruded starch foams and thermomoulded starch films. A collection of starch foam samples from 1% to 70% amylose (99%-30% amylopectin) processed under various extrusion conditions has been used. The alveolar structures of foams are characterized by various densities (from 98 to 465 kg/m(3)), cell size, and median cell wall thickness. The kinetics of water uptake are measured and fitted by using the Peleg model. It is shown that the larger the size of the alveoli and the thinner the walls, the greater the water uptake, whatever the amylose-amylopectin composition of the walls. The water uptake of films is controlled by the thickness of films (from 0.25 to 1 mm) and the amylose-amylopectin composition, with a threshold value of amylose content between 40% and 50%.

There is growing interest in turning the by-products of agricultural processes into biobased and biodegradable materials. The complexity of composition and structure of biomass makes it difficult to understand the mechanisms involved in its transformation into materials, requiring model systems. In this study, solid materials were obtained from model cellulosic fibers (modulus of 5.5-5.8 GPa) and biomass from brewery co-products (modulus of 2.2-2.6 GPa) using uniaxial compression. Their properties were comparable to or exceeded those reported for conventional binderless cellulosic materials processed at higher temperatures (similar to 200 degrees C), thus highlighting the efficiency of our low-temperature process. The effect of the fiber size and composition, of the processing temperature on the resulting samples mechanical properties was assessed. We show that longer initial fibers, with higher aspect ratio, led to improved flexural modulus and strength due to a higher degree of fiber entanglement, which translated into better performance for the less transformed biomass. While purely cellulosic samples displayed better mechanical properties than those prepared from biomass at a pressing temperature of 100 degrees C, the increase to 140 degrees C closed the gap between the two biomasses particularly in terms of water resistance due to a reduced porosity. Finally, model cellulosic polymers improved the water resistance of the cellulosic samples due to the formation of water tight matrix. This low temperature, binder-free method is promising for the green transformation of biomass coproducts.

This study investigates the influence of proteins and arabinoxylans contents of wheat grain on the dough extensional properties, critical determinants of bread quality. Thirty-seven wheat samples (37) were selected from an initial set of 150 wheats, according to technological criteria, including water absorption (WA), to assess the impact of natural variability of several protein and arabinoxylan (AX)-related features on dough behaviour. Dough were prepared at the hydration level determined by the WA Farinograph tests. TD-NMR results showed that, for all samples, the dough reached an optimal hydration state, reflected by a four-peak time distribution. Rheological tests were performed on dough samples at low deformation with Dynamic Mechanical Thermal Analysis (DMTA), and at large deformation, using Lubricated Squeezing Flow test (LSF). Results indicate that the maximum storage moduli E'max determined by DMTA, at temperature close to 70 degrees C, is primarily influenced by initial gluten network cross-linking. E'max decreased between 1.1 MPa and 0.6 MPa, with increasing wet gluten content from 17.2 to 40 g/100g. At large deformation, the extensional viscosity of all doughs followed a power law, from which was derived the consistency index K. Surprisingly, K increased from 11,100 to 22,200 Pa.sn when the intrinsic viscosity of water extractable arabinoxylans increased from 420 to 820 mL/g, n being the flow index of the dough. Results showed that the extensional viscosity is more closely affected by the AX characteristics than by protein characteristics. These results were interpreted in terms of supramolecular distribution of the gluten network and the entangled arabinoxylans in the liquid phase, and discussed for their possible impact on bread making for a wide range of wheats.

Lentils are gaining attention with the rise of plant-based diets, yet their consumption remains limited, partly due to poor canning quality. To identify the factors affecting canning performance in Anicia lentils, three seed batches differing in quality were analysed in the dry state, during soaking, and during cooking. Assessments included seed appearance, morphology, histology, composition, mechanical properties, and hydration behaviour. High-quality seeds had a lower initial hydration rate during soaking and a lower moisture equilibrium during cooking (140 % vs. 180 %), linked to greater deformability. They contained less amorphous starch (10 % vs. 15 %), more pectic homogalacturonans (1.3 % vs. 1.1 %) in cotyledons, and fewer intercellular spaces. These findings clarify the roles of the lentil seed coat and cotyledons, particularly with regard to pectin and starch, in water absorption and texture loss during cooking.

Additive Manufacturing by Molten material Extrusion (AM-ME) of biocompatible and edible parts based on natural biopolymers, such as zein, a protein extracted from corn, opens prospects for applications in the pharmaceutical field. Cohesion between deposited layers requires filament spreading and diffusion of macromolecules at the interface. Viscous sintering has to be characterized and modelled in the case of zein, to better control its processing in the molten state. Sintering kinetics of polymer melts is generally assessed in an instrumented furnace and modelled using the Frenkel-Eshelby approach. It is based on the evaluation of the growth rate of the bonding neck between two circular parts, linked to the melt's surface tension (Gamma), the driving force, and viscosity (eta). It was recently completed by the acquisition of 3D scans by dynamic X-ray tomography (5.2 mu m pixel size, 1 scan/s) on the ANATOMIX beamline of Synchrotron SOLEIL, to follow the hot-melt sintering of 4 filaments (L-Filament=5 mm, (sic)(Filament)=2 mm) disposed in two layers. The analysis of the reconstructed volumes leads to assess the decreasing size of the central pore during sintering. 2D modelling is carried out by FEM combined to Level Set with COMSOL Multiphysics (R). It requires a simplification of the geometry according to an axial symmetry and an adaptive time-stepping. At 120 degrees C, a typical temperature to process plasticized zein, simulated and experimental sintering are similar, with a decrease rate of the central pore at about 1%/s. Increasing sintering rates are obtained as the temperature and surface tension increase.

Dough extensional properties obtained from 14 wheat flours hydrated at 50 ε̇_̇ḃ = 0.25 s−1 (R2 = 0.99 ± 0.01 for 14 flours). The flow index (n = 0.36) and strain hardening index (SHI = 1.73) are kept constant. The model is validated by comparing the stress values calculated from the alveogram to those measured in LSF for wheat flour doughs hydrated at 50 ε̇_̇ḃ < 2.5 s−1. Therefore, the Alveograph, which allows classifying flours according to several dough stretching properties, also provides access to the model of dough extensional behavior. Determining dough extensional properties for alveograph test and validating by comparison with resutls obtained by LSF

Wheat flour doughs were prepared from four commercial wheat flours at different mixing times and hydration levels in order to obtain variations in their rheological properties and gluten network structure. Their rheological behavior was assessed by Dynamic Mechanical Analysis (DMA) for their viscoelastic properties and by Lubricated Squeezing Flow (LSF) for their extensional properties. Gluten network structure was determined by quantitative analysis of confocal microscopy (CLSM) images. Among the rheological properties, the consistency index (k) derived from the extensional viscosity and the elastic modulus ratio (E ' Max/E ' Min) varied between 10 and 42 kPa. sn, and 4 and 26, respectively. They were found to be consistently linked to the gluten network structure. This structure was primarily described by the morphological descriptor, "protein width", which defines the thickness of protein strands, the average value of which varied between 1.7 and 2.5 mu m. Both rheological properties and morphological criteria were significantly influenced by dough hydration rather than by mixing time, whereas the flour characteristics did not play a major role. Interpretation of these results, supported by previous 1H time domain nuclear magnetic resonance (TD-NMR) results concerning water distribution profiles, showed that an optimal dough is defined by a high dough consistency index (k) and a highly cross-linked gluten network (low E'Max/E'Min ratio), presenting thin protein strands.

The development of porous, water-resistant cellulose-based materials with shape-recovery performance requires control of the swelling behaviour of these materials. In this context, TEMPO-oxidized CNF (CNFt) cryogels, were prepared by non-directional (ND) and unidirectional (UD) freezing step followed by freeze-drying to obtain lightweight porous materials (22.6 kg m -3 and 98% air content), CNFt-ND ou CNFt-UD, with different pore morphologies. Indeed, honeycomb-like or lamellar structures were obtained as evidenced by microscopy and X-ray tomography analysis. Determination of cryogels absorption capacities in water (pH 6) or HCl (pH 2) solution showed different swelling behaviours depending on the charge state of carboxyl groups, but also on pore morphology NFCt cryogels. Measurements of 1 H T 2 relaxation times using Low-Field (LF) NMR demonstrated the appearance of different population of water molecules characterized by different mobilities due to the structuration of NFCt gel during the freeze-casting procedure. Finally, tests of compression cycles on H 2 O- or HCl-swollen NFCt-ND and NFCt-UD cryogels demonstrated the higher compressive resistance of swollen-cryogels after protonation and a recovery shape performance of about 87% was obtained after 50 compression cycles.

Zein, a biopolymer from corn, was plasticized by glycerol and an Active Pharmaceutical Ingredient-Ionic Liquid (API-IL) for its melt processing at 130 degrees C. In order to enhance the rheological properties of the formulation for 3D printing, the ratio of glycerol to API-IL was adjusted while maintaining a consistent addition of 20% plasticizer. A 50/50 ratio allowed obtaining an initial melt viscosity suitable for extrusion-based processes, at approximately 1 kPa.s at a shear rate of 10 s-1, with a shear thinning behavior. This viscosity remained stable during a processing window of about 6 min, before zein proteins start to aggregate, leading to an apparent gelation phenomenon for long residence times. The processability of this formulation containing API-IL for the printing of tablets for potential therapeutic applications was confirmed by tests on a 3D printer. Nonetheless, in comparison to a reference formulation containing only glycerol, the printing accuracy experienced a decrease. This was ascribed to slower viscous sintering kinetics in presence of API-IL, evidenced by monitoring fusion-bonding during dynamic X-ray tomography trials carried out at Synchrotron SOLEIL.

An in vitro approach is proposed to study the release of an Active Pharmaceutical Ingredient-Ionic Liquid (API-IL) from a natural biopolymer matrix based on zein, a maize storage protein. Zein can be processed in the molten state with 20 w% [Lidocainium][Ibuprofenate] added as API-IL also acting as plasticizer and potentially co-plasticized by glycerol. The thermal stability of the matrix is checked, as well as the in vivo biological activity of the API-IL confirming anesthetic and anti-inflammatory activities. Model tablets are thermomolded at 130 °C (∅20 mm, 0.2 mm thick) and submitted to simulated digestion based on the INFOGEST static protocol of gastrointestinal food digestion at 37 °C (2 h under gastric conditions followed by 2 h under intestinal ones). The release of the API-IL is evaluated by HPLC-UV to dissociate lidocainium, that shows a progressive release (35 % after 2 h and 60 % after 4 h digestion), from ibuprofenate, that is mainly released under intestinal conditions due to low solubility in acidic conditions. The monitoring of the tablets reveals release mechanisms based on diffusion without noticeable erosion of the matrix. These results demonstrate the interest of this thermoplastic material to provide a relevant drug delivery system.

The viscous sintering kinetics of thermoplastic polymers is generally studied by monitoring the evolution of the bonding neck between two particles (spherical, or cylindrical) and using a refined Frenkel-Eshelby’s model. Recently, we showed that the entire contour of sintering filaments could be modelled by lemniscates as figure-eight shape curves to assess bonding abilities of a 3D-printable plasticized biopolymer. Using COMSOL Multiphysics® software, we set up a 2D finite element model of thermoplastic filaments’ viscous sintering with flow front tracking by the level set method. This leads to contrasted images of the two phases, i.e. air and polymer, allowing the prediction of the shape of the interface corresponding to the filaments’ contour. An image analysis procedure is applied to the simulated sequences and the ones acquired during sintering trials of extruded filaments based on zein, a corn protein plasticized by 20w% glycerol. This method is based on the assessment of the coordinates of sintered filaments’ edge pixels and their fitting by lemniscates of Booth. We show that the 2D FEM approach combined with level set method allows simulating the hot melt viscous sintering of a 3D-printable thermoplastic biopolymer as a two-phase flow. Furthermore, the image analysis is successfully applied to simulated and experimental sequences, thanks to the monitoring of the filaments’ contour, to assess their bonding kinetics and check its modelling.

A method for image analysis was implemented to determine the edge pixels of two biopolymer-based thermoplastic filaments during their hot melt isothermal sintering at 120 °C. Successive inverted ellipses are adjusted to the contour of the sintered filaments and lead to the identification of the parameters of the corresponding lemniscates of Booth. The different steps of the morphological image analysis are detailed, from 8-bit coded acquired images (1 frame/s), to the final fitting of the optimized mathematical functions describing the evolution of the filaments envelope. The complete sequence is composed of an initial pure viscous sintering step during the first minute, followed by viscoelastic swelling combined with melt spreading for a longer time, and then the stabilization of the sintered filaments shape for over 2 min at high temperatures. Using a master curve obtained from Hopper's abacus, the characteristic viscous sintering time is assessed at tvs = 78 s, confirming the one previously found based on the measurement of the bonding neck length alone. Then, the full description of the evolution of the thermoplastic filaments envelope is assessable by image analysis during sintering trials as a result of its digital modeling as successive lemniscates of Booth, reflecting geometry changes in the molten state.

Viscous sintering kinetics of thermoplastic polymers has been studied for powders using models refining the Frenkel-Eshelby approach. It is usually based on the measurement of the bonding neck between two molten particles submitted to thermo-microscopy trials. Recently, specific experimental setups have been described for studying the viscous sintering of filaments used in additive manufacturing by FDM. The description of their coalescence by models developed for particles is a rough approximation. However, the evolution of the shape of their section can be modelled by lemniscate curves. In the present work, we present an advanced image analysis approach allowing the fitting of the contour of the filaments by a Lemniscate of Booth. It is based on the automatic assessment of the coordinates of their edge pixels and the adjustment of lemniscates to match their evolving shape as a succession of inverse ellipses. We apply this procedure to a model-biopolymer recently shown as 3D-printable, the plasticized zein, a corn protein extruded as cylindrical filaments. Their sintering is recorded at 120°C as 8-bits coded raw images. After segmentation, a numerical mask is applied to follow the filaments outline. Using Matlab® as computer algebra system, the adjustment and the identification of lemniscates parameters leads to determine the viscous sintering characteristic time, similar to those of standard polymers. Then, the full monitoring of sintering kinetics is achievable and makes possible a better modelling of such experimental trials and their application to enhance the control of the welding between layers in additive manufacturing.