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.

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.

Hypothesis: Pea proteins can act not only as interfacial stabilizers of oil-in-water emulsions but also as gelling agents in the continuous phase. Protein gelation, rather than droplet jamming, may be the main mechanism of emulsion stability, providing a physical explanation for the creaminess of high-protein plant-based emulsions. Experimental: Spin-echo small angle neutron scattering (SESANS) with D₂O/H₂O contrast variation was used to study 15% pea protein dispersions and emulsions with 40–60% rapeseed oil, 7.5% protein at pH 3 to 6.5. SESANS investigates length scales up to tens of micrometres, enabling simultaneous analysis of protein networks and oil droplets without dilution. Complementary small angle X-ray/neutron scattering were used to validate protein aggregate size, and hydration. Findings: Protein dispersions at neutral pH formed mass fractal networks with small individual building blocks (radius ∼38 Å, hydration ∼70%). Emulsions consisted of oil droplets embedded in these networks, with droplet radii decreasing at higher oil fractions due to an effective higher protein concentration in the continuous phase, creating a denser network. Dispersions and emulsions at lower pH contained aggregated clusters of denatured proteins. These coarse and inhomogeneous networks gave increasing droplet radii at lower pH. Contrast variation enabled the separation of protein and oil droplet scattering, demonstrating that protein gelation rather than droplet jamming is the main mechanism of stability. This gives a physical explanation of the high viscosity of high-protein plant-based emulsions and is promising for these plant materials to be used as gelling agents in food applications.

Capillary suspensions are unique materials, in which the rheological properties can be tuned by controlling the particle network through capillary interactions. To gain insights into the influence of particle properties on the network formation and accompanying gel strength for water-absorbing, biopolymeric particles, protein particles of two different sizes and water absorption capacities (WACs) were prepared. Utilizing SESANS, we describe a novel approach towards detecting changes in water distribution between and within particles. While effects of WAC seemed to be overpowered by concurrent variations in surface roughness, a larger particle size or lower roughness led to a lower initial gel strength and a subsequent much larger relative increase in gel strength upon water addition. Even though similar maximum gel strengths were obtained, indicating that particle properties had a comparably small influence once capillary forces dominated the systems, particle size played a critical role for network collapse with increasing particle clustering at larger water volumes. The results pinpoint subsequent knowledge gaps in the existing literature and demonstrate the tunability of biopolymer-based capillary suspensions over a wide gel strength range by adjustment of particle properties. These insights offer exciting opportunities for application of capillary-force controlled systems in the food, pharmaceutical and cosmetic industries.

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.

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.

We conduct simulations of Spin Echo Small Angle Neutron Scattering (SESANS) by employing Monte Carlo methods to a setup using four magnetic Wollaston prisms. Our primary focus involves the validation of these models, encompassing monochromatic scenarios across various neutron wavelengths to ascertain the reliability of the simulations. Subsequently, we extend this validation to encompass simulations in time-of-flight mode. Our model consistently and precisely predicts the scattering patterns emanating from dilute spheres in both monochromatic and time-of-flight modes. Notably, it also accurately reproduces the intricate encoding associated with scattering occurring between the third and fourth magnetic Wollaston prism, which provides us with another approach to increase the solid angle coverage of a SESANS instrument. This validation process conclusively demonstrates the efficacy of our simulation methods. Importantly, it paves the way for simulating more intricate and realistic instrumental configurations, broadening the horizons for future research endeavours.

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. [...]

We have used spin-echo small-angle neutron scattering (SESANS) to probe the hierarchy of structures present in polymer–carbon nanocomposites, with length scales spanning over three orders of magnitude, from 10 nm to 16 μm. The data processing and reduction show a unified approach across two SESANS instruments (TU Delft and Larmor at the ISIS neutron source) and yield consistent data that are able to be modelled using well-established hierarchical models in freely available software such as SasView. Using this approach, we are able to extend the measured length scales by over an order of magnitude compared to traditional scattering methods. This yields information about the structure in the bulk that is inaccessible with conventional scattering techniques (SANS/SAXS) and points to a way for interrogating and investigating polymer nanocomposites routinely across multiple length scales.

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.

The spin-echo small-angle neutron scattering (SESANS) technique utilises a series of inclined magnetic fields before and after the sample to encode the scattering angle into the polarisation to obtain a much higher resolution than in conventional SANS. The analogous technique (spin echo modulated SANS (SEMSANS)) implements spin manipulations before the sample only to encode the scattering into an intensity modulation. The technique can be combined with SANS to expand the length scale range probed from 1 nm to microns. Using McStas we show that using a series of four magnetic Wollaston prisms in two orthogonal pairs with a 90° rotation can be utilised to create SEMSANS modulations in 2-D. These modulations can also be of different periods in each encoding direction. This method can be applied to anisotropic scattering samples. Also this allows for the simultaneous measurement at two orthogonal independent spin-echo lengths. This technique yields directly information about the structure of oriented structures.

Interactive Textbook.

Het boek is een algemene introductie in het elektromagnetisme, zoals in de meeste Amerikaanse universiteiten in het eerste jaar wordt gegeven. Uiteindelijk worden de wetten van Maxwell in integraal-vorm gegeven. De begrippen elektrische lading, krachten en velden worden beschreven. Hieruit wordt het begrip potentiaal gedefinieerd, met als toepassing de condensator. Vervolgens wordt er een link gelegd tussen het macroscopische en microscopische beeld van elektrische stroom. De relatie tussen stroom en magnetisch veld wordt gelegd en geïllustreerd aan de hand van spoelen. Het gedrag van condensatoren en spoelen in wisselstroomschakelingen wordt afgeleid. Tot slot laten we zien dat elektromagnetische golven voldoen aan de wetten van Maxwell.

De studenten leren de wetten van Maxwell toe te passen in eenvoudige problemen. Ze leren grootheden uit te rekenen en eenvoudige afleidingen te maken. Ze passen symmetrie toe om een probleem wiskundig sterk te vereenvoudigen.

The organization of chromatin in the nuclei of rat lymphocyte was studied by time-of-flight spin-echo small-angle neutron scattering (ToF-SESANS). The procedures of the measurements in ToF and monochromatic SESANS modes were compared. It is shown that the sensitivity of the ToF method is significantly higher than that of the monochromatic mode. As a result, the SESANS correlation function can always be extracted from the ToF measurement of polarization, while this is not always the case with the monochromatic mode. The applicability of SESANS to fractal objects at the micrometre scale is demonstrated. The SESANS correlation function is well fitted by the exponential decay G(z) = exp(−z/ξ) with the correlation length ξ = 3.7 ± 0.1 µm. The exponential decay of the SESANS correlation function can be connected to the logarithmic correlation function γ(r) = ln(r/ξ) and the cubic law of the scattering intensity I(Q) = Q−3, which is in agreement with the concept of scattering from fractal objects. This finding is interpreted as evidence of a very specific logarithmic fractal structure of the large-scale organization of chromatin. The model of the logarithmic fractal is visualized as a hierarchical object obeying the volume-conservation principle at different scales.

A round-robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions and two from powders. Most of the 46 participants correctly identified the number of populations in the dilute dispersions, with half of the population mean entries within 1.5% and half of the population width entries within 40%. Due to the added complexity of the structure factor, far fewer people submitted answers on the powder datasets. For those that did, half of the entries for the means and widths were within 44 and 86%, respectively. This round-robin experiment highlights several causes for the discrepancies, for which solutions are proposed.

A novel spin echo small-angle neutron scattering (SESANS) concept based on a rotationally symmetric magnetic field geometry is introduced. The proposed method is similar to the conventional linear SESANS technique but uses
longitudinal precession fields and field gradients in a radial direction, as typically found in neutron spin echo (NSE) spectrometers. Radial SESANS could thus be implemented as an add-on to NSE setups. The neutron trajectory through the
instrument is encoded with the help of radial gradients generated by radial shifters, which are coils placed in the beam area similar to Fresnel coils. The present work introduces the setup of the instrument and explores its performance and the relationship between the encoded momentum transfer and the precession angle. The results indicate that radial SESANS is only sensitive to scattering along the radial direction and thus measures the projected correlation function along this direction as a function of the spin echo length, defined similarly to linear SESANS. For an evaluation of the performance of the setup, the case of scattering from solid spheres is considered and the results calculated for the radial and linear SESANS cases are compared. Also discussed is the implementation of the radial magnetic field geometry in spin echo modulated small-angle neutron scattering.

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.

For the further development of spin-echo techniques to label elastic scattering it is necessary to perform simulations of the Larmor precession of neutron spins in a magnetic field. The details of some of these techniques as implemented at the reactor in Delft are simulated. First, the workings of the magnetized foil flipper are simulated. A full virtual spin-echo small-angle neutron scattering instrument is built and tested without and with a realistic scattering sample. It is essential for these simulations to have a simulated sample that also describes the transmitted beam of unscattered neutrons, which usually is not implemented for the simulation of conventional small-angle neutron scattering (SANS) instruments. Finally, the workings of a spin-echo modulated small-angle neutron scattering (SEMSANS) instrument are simulated. The simulations are in good agreement with theory and experiments. This setup can be extended to include realistic magnetic field distributions to fully predict the features of future Larmor labelling elastic-scattering instruments. Configurations can now be simulated for more complicated combinations of SANS with SEMSANS.

Functionalized biomass waste sources of cellulose have drawn attention due to their high availability and sustainability properties. In this work we characterize the structural and flow properties of high-pressure homogenized citrus fiber cellulose dispersions, employing SAXS, rheology and rheo-MRI techniques. The high-pressure treatment disrupts the microfibrillar network within the citrus fibers, but leaves the individual microfibrils intact. Under moderate shear (0.1-100 s^-1) in a confined (<1 mm) geometry, these functionalized citrus fiber cellulose dispersions exhibit thixotropic shear-banding behavior accompanied by cooperative flow of microfibril flocs with correlation lengths ξ ~ 100 μm. The presented findings form a basis towards understanding and manipulating the structural and rheological properties of non-wood biomass cellulose microfibrils under industrially-relevant conditions.

Spin-echo small-angle neutron scattering (SESANS) yields structural information on length scales from 30 nanometres up till 20 micrometres. These length scales match nicely those of colloids, protein networks and fat droplets, which are present in many food materials. This makes SESANS an excellent probe to study food materials. An interesting feature of SESANS is the real space character of the raw data. Several examples of quantitative neutron scattering studies on food materials are shortly reviewed.