The development of novel plant-based meat alternatives that closely mimic the anisotropic structure of animal meat offers a solution to mitigate the adverse effects of animal meat consumption. The currently most widely adopted production route is shear processing through high-moisture extrusion (HME). The complex structure formation mechanisms that determine the final fibrous texture of extrudates have yet to be fully understood. The main obstacle is the lack of multiscale studies investigating the principles governing structure formation from the nano- to the macro-structural level. This work aims to address this knowledge gap by studying materials, collected after a dead-stop operation of an industrial pilot-plant scale extruder, with multiple characterisation techniques, such as Magnetic Resonance Imaging (MRI) and Small-Angle Scattering (SAS). We demonstrate that the nm- to μm-scale structure is formed already within the extruder barrels, and that sub-mm-scale anisotropy develops within the cooling die. Furthermore, we show that diffuse light reflectance (DR) probes the size and coarseness of the lamellar phase-separated regions.

Soy protein isolates (SPIs) and concentrates (SPCs), which primarily consist of glycinin (11S globulin) and β[jls-end-space/]-conglycinin (7S globulin), are the dominant ingredients in the production of plant-based meat products using high-moisture extrusion (HME). Yet the links between their gelation and structure formation under HME are not fully understood. In this work, we employ small-angle scattering (SAS) techniques, complemented by rheology, on heat-set gels to elucidate the multiscale aggregation pathways of fractionated 11S and 7S globulins, and relate these to the extrudate structure. Heat-set gels revealed a three-level structural hierarchy: compact protein units that persist after heating; aggregates whose mid-scale size and morphology vary with pH; and networks characterised by clustering strength. Near the isoelectric point (pI), both globulin-enriched fractions formed particulate gels. Under these conditions, 7S globulin-enriched gels were stiffer because their smaller aggregates created a higher density of contacts per unit volume, resulting in a higher clustering strength. Away from the pI, fibrillar aggregation dominated, and 11S globulin-enriched gels became stiffer as a result of forming thicker and more tightly connected strands. At pH 7, blending experiments revealed that even small additions of 7S globulin weaken the gels; however, under HME, the same additions enhance anisotropy. Specifically, 7S globulin promotes deformability and alignment, while 11S globulin contributes to network strengthening through covalent crosslinks. Together, these results establish parallels between heat-induced gelation and extrusion, highlighting the complementary roles of 11S and 7S globulins in structuring high-moisture extrudates of soy proteins.

Acid and rennet gelation are essential processing steps for dairy products such as cheese and yoghurt. The coagulation and gel properties of these gels differ depending on whether unheated or heated milk was used. However, these heat-induced effects occur to a different extent in goat and cow milk gels, and have yet to be determined on a micro- and nanoscale structural level. To obtain a better understanding of heat-induced structural changes, this study investigates non-heated and heated casein micelle solutions from goat and cow milk and their derived rennet and acid-induced gels by a multi-technique approach, combining rheology, confocal scanning laser microscopy, and spin-echo small-angle neutron scattering (SESANS). This work is thereby the first to describe heat-induced changes of caseins and casein gels using SESANS. Modeling casein micelles as sticky hard spheres shows that goat caseins are larger and less hydrated than their cow counterparts. SESANS data reveal that structural changes observed in rennet and acid gels follow opposite trends when milk was pre-heated. Modeling gels as fractal gels suggests a connection between heat treatment and changes in the arrangement of caseins to form more loose or compact aggregates. Cow milk gels showed larger heat-induced changes in SESANS and corresponding larger rheological changes than goat milk counterparts. This work shows that rennet and acid gels respond differently to pre-heat treatment, and that they differ in the compactness of their casein network. The findings from this study can contribute to the design and characterization of dairy products of different animal species.

Spin-echo small-angle neutron scattering (SESANS) is a unique method to measure structures of materials in real space with length scales from ∼ 30 μm to ∼20 µm [1]. As shown in Figure 1, the accessible length scale of SESANS is given by its ability to encode the momentum transfer into the Larmor phase, namely Φ = →δ . →Q, where →Q is the momentum transfer and →δ is the encoding vector of the setup and its projection along Q (δQ) is called spin-echo length (SEL). [...]

High-moisture extrusion (HME) is a proven industrial food processing technique used to create textured plant-protein materials that can serve as alternatives for animal meat. The required multiscale anisotropic structure of the extrudate can be achieved by selecting suitable HME process conditions, as well as by pH-shifting. In this work, we explored pH-shifting via the water feed, which is an attractive industrially-scalable approach. Soy protein concentrate (SPC) was extruded on lab-scale and extrudates were characterized ex situ, from molecular to mm scale, using Diffuse Reflectance (DR), Magnetic Resonance Imaging (MRI), Small-Angle-Scattering of Neutrons (SANS) or X-rays (SAXS). pH-shifting had a non-monotonic effect on extrudate hardness and anisotropic structure at both sub-mm (MRI) and μm (DR) scale. At the sub-μm scale, SANS and SAXS data indicated that, at pH > pI, the radius of protein nano-aggregates monotonically increases, accompanied by a transition from particulate to fibrillar protein aggregation. When pH was further shifted to alkaline conditions, the decrease in clustering strength and nematic order parameter pointed to an increase in intra- and inter-fibrillar repulsion, respectively. Protein extractability experiments indicated that the effects of pH-shifting on anisotropic structure formation could not be attributed to covalent intermolecular crosslinking. Thus, repulsive non-covalent electrostatic protein-protein interactions play a dominant role in the formation of multiscale anisotropic structure during SPC extrusion. The formation of an optimal anisotropic SPC extrudate structure is determined by the pH-dependent balance between fibrillar nano-aggregate clustering and electrostatic repulsion. Alkalization or acidification via the water feed implies that protein charge and structure may not be in equilibrium yet with the imposed pH conditions. The transient nature of pH-shifting via the water feed results in an intricate interplay with extrusion conditions. Therefore, control of anisotropic structure formation, via the water feed, in SPC extrudates, is extruder specific.

Since macroemulsions are only kinetically stable, characterizing their behavior as they change over time is relevant to their application. Time-of-flight spin-echo small-angle neutron scattering (SESANS) enables time-resolved measurement of the bulk evolution of concentrated, opaque emulsions without perturbing the system. Here, we present time-of-flight SESANS measurements of an n-decane-in-DMSO emulsion stabilized by Pluronic P-123, where changes in the system as it ripened were resolved. The radius of emulsion droplets were shown to grow over time with a rate of 25 μm3 h–1, suggesting that Ostwald ripening is the dominant aging process. Furthermore, SANS measurements revealed the presence of a stable population of swollen surfactant micelles, providing an additional mechanism for mass transfer between particles. Since time-of-flight SESANS can be used to obtain information about particle sizes, ripening rates, and associated processes, it is uniquely suited for studying the behavior of dense colloidal systems over time.

This study treats a detached homogenous low-crested structure (HLCS) made of Cubipod concrete elements placed seaward of a vertical wall (forming a basin in between) to reduce overtopping. Assessing the complex hydrodynamics and effects of changing the geometry of such a system in relation to overtopping reduction is challenging. The numerical model OpenFOAM was applied to this end. Forchheimer coefficients for wave transmission and the flow through the HLCS were calibrated and validated using existing physical modeling data (α = 500 and β = 1.0, with varying porosity based on the Cubipod shape), while the effect of the basin and vertical seawall was determined fully numerically. The crest freeboard (R_c), crest width (B), and basin length (L_B) were the main geometrical parameters that influenced the performance of the HLCS in reducing overtopping. An exponential decay was observed in the overtopping discharge when the values of these geometrical parameters increased. As L_B increased, this decay was primarily due to the dissipation of the broken-wave bores. The largest gradient in the predicted overtopping discharge was noted at R_c/H_s,i ≈ 0, B/H_s,i ≈ 4.5, and L_B/L_p ≈ 1.2, where H_s,i is the incident significant wave height and L_p is the peak wavelength in the basin.

Sustainability, health and animal welfare concerns drive consumers to plant-based meat alternatives, but their mouthfeel is still lacking. Mimicking the complex fibrous meat structure is key for alternative whole-cut products to be accepted by meat lovers. A recent study, published in Food Hydrocolloids, shows what neutrons and X-rays tell us about hierarchical structure formation of soy-based meat alternatives. This is a multi-institutional study by scientists from the Delft University of Technology, Wageningen University & Research, ISIS Neutron and Muon Source and the European Synchrotron Radiation Facility. [...]

Plant-based meat alternatives are seeing considerable interest due to their potential to reduce environmental burden and enhance population health. The food industry, therefore, seeks routes to provide the consumer with whole-cut plant-based products that closely resemble meat products. High-moisture extrusion (HME) of plant proteins enables the industrial manufacturing of meat-like products with highly hierarchical structural organisation of fibres. The major bottleneck in serving the growing market for these products is a lack of insight into
how multiscale structures evolve during shear processing. Furthermore, it remains an open question of how two biopolymers, one being a plant protein and the other being a polysaccharide, contribute to the anisotropic structure formation during HME. This study shows how the complementary use of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) can add clarity to these matters, benefiting from the different contrasts in scattering length density (SLD) encountered with each of these methods. It is demonstrated that two
biopolymers have differences in the development of structural anisotropy. The protein fibril alignment starts in the extruder section with its further development along the cooling die. On the other hand, for polysaccharide fibres, the strongest local alignment has been found in the transition zone.

Waterborne polyurethane (WPU) has attracted significant interest as a promising alternative to solvent-based polyurethane (SPU) due to its positive impact on safety and sustainability. However, significant limitations of WPU, such as its weaker mechanical strength, limit its ability to replace SPU. Triblock amphiphilic diols are promising materials to enhance the performance of WPU due to their well-defined hydrophobic-hydrophilic structures. Yet, our understanding of the relationship between the hydrophobic-hydrophilic arrangements of triblock amphiphilic diols and the physical properties of WPU remains limited. In this study, we show that by controlling the micellar structure of WPU in aqueous solution via the introduction of triblock amphiphilic diols, the postcuring efficiency and the resulting mechanical strength of WPU can be significantly enhanced. Small-angle neutron scattering confirmed the microstructure and spatial distribution of hydrophilic and hydrophobic segments in the engineered WPU micelles. In addition, we show that the control of the WPU micellar structure through triblock amphiphilic diols renders WPU attractive in the applications of controlled release, such as drug delivery. Here, curcumin was used as a model hydrophobic drug, and the drug release behavior from WPU-micellar-based drug delivery systems was characterized. It was found that curcumin-loaded WPU drug delivery systems were highly biocompatible and exhibited antibacterial properties in vitro. Furthermore, the sustained release profile of the drug was found to be dependent on the structure of the triblock amphiphilic diols, suggesting the possibility of controlling the drug release profile via the selection of triblock amphiphilic diols. This work shows that by shedding light on the structure-property relationship of triblock amphiphilic diol-containing WPU micelles, we may enhance the applicability of WPU systems and move closer to realizing their promising potential in real-life applications.

By introducing hydrophilic polymers into silicone medical devices, highly beneficial biomedical properties can be realized. An established solution to introduce hydrophilic polymers is to form an interpenetrating polymer network (IPN) by performing the hydrogel synthesis in the presence of silicone swollen in supercritical carbon dioxide. The precise distribution of the two polymers is not known, and determining this is the goal of this study. Neutron scattering and microscopy were used to determine the distribution of the hydrophilic guest polymer. Atomic force microscopy revealed that the important length scale on the surface of these materials is 10–100 nm, and spin-echo small-angle neutron scattering (SESANS) on IPNs submerged in D₂O revealed structures of the same scale within the interior and enabled quantification of their size. SESANS with hydration by D₂O proved to be the only scattering technique that could determine the structure of the bulk of these types of materials, and it should be used as an important tool for characterizing polymer medical devices.