Small Amplitude Oscillatory Shear Tests Research Articles

On the linear viscoelastic behavior of semidilute polydisperse bubble suspensions in Newtonian media

In this work, we investigated the linear viscoelasticity of semidilute polydisperse bubble suspensions via small amplitude oscillatory shear (SAOS) tests performed in a rheo-optical setup. For all tested suspensions, the measured viscoelastic moduli (G′, G″) aligned with the theoretical predictions of the Jeffreys model for average dynamic capillary numbers (⟨Cd⟩) greater than unity. But at lower ⟨Cd⟩ values, experimental G′ values exceeded theoretical predictions. To investigate this, we considered the effects of suspension polydispersity and various SAOS measurement artifacts, including bubble rise, coalescence, and changes in suspension microstructure over time. Polydispersity could not cause the observed deviation, because the viscoelastic trends deviate from those of classic single-mode relaxation only for bimodal bubble size distributions with equal volume fractions of very small and very large bubbles; in any other case, the polydisperse suspension behaves as monodisperse with a bubble radius equal to the volume-weighted mean radius. Furthermore, bubble rise proved to play a minor role, while SAOS rheo-optical experiments revealed that bubble size and organization varied negligibly during our measurements. The G′ deviation at low ⟨Cd⟩ values was linked to bubble fluid dynamic interactions induced by the bubble spatial distribution. Image analysis showed that at low bubble volume fractions, stronger and prolonged preshearing reduces these interactions by increasing the average interbubble distance. But this effect is negligible in denser suspensions, which show similar G′ trends for any applied preshearing. Finally, a multimode Jeffreys model fitted to the experimental data showed that bubble interactions complicate the relaxation process, introducing multiple relaxation modes.

Acid-induced gels from mixtures of micellar casein and pea protein: Effect of protein ratio and preheating route

Enhancing the sustainability of dairy products through the partial substitution of dairy proteins with plant proteins requires exploring formulation and processing strategies. This study investigates the gluconic-δ-lactone (GDL)-induced hybrid gels from commercial micellar casein isolate (M) and pea protein isolate (P) dispersions (5% w/w protein content). Variations in the M/P ratios (3:1, 2:2, and 1:3) and preheating routes (Route 1: preheating M and P dispersions together; Route 2: preheating them separately) impacted the physical/conformational properties of protein dispersions as well as the rheological/structural features of resulting gels. Small and large amplitude oscillatory shear (SAOS and LAOS) tests revealed that lower M/P ratio led to earlier gelling points and increased the stiffness and elasticity of hybrid gels in the linear viscoelastic (LVE) region. All gels transitioned from elastic to plastic behavior in the non-linear viscoelastic (NLVE) region, with lower M/P ratio showing reduced stretchability and faster structural breakdown. Regardless of routes, the preheating step (95 °C, 30 min) disintegrated inherent aggregates/agglomerates in these commercial protein ingredients, leading to smaller particle size, but higher protein solubility, surface hydrophobicity, and |ζ-potential|. Pea proteins formed soluble aggregates during preheating, but the presence of micellar caseins (Route 1) hindered this process. Consequently, mixtures with lower M/P ratio and from preheating route 2, possessed higher quantities of pea protein soluble aggregates, forming a compact gel network with low water mobility, as observed by CLSM, STED, and LF-NMR. These findings show the potential for using pea proteins in acid-induced gel foods like yogurt and paneer-type cheeses.

Melt flow characterization of highly loaded cooper filled poly(acrylonitrile-co-butadiene-co-styrene)

The knowledge of the rheological behavior of hybrid polymer melts is essential to develop fused deposition modeling (FDM) filaments to print metal and ceramic goods. In this contribution, we performed an in-depth analysis of the morphology and the rheological behavior in the linear elastic domain of poly(acrylonitrile-co-butadiene-co-styrene) (ABS) highly filled with copper microparticles functionalized by bioinspired polydopamine, containing polyethylene waxes (PEW) as lubricant agent. The composite systems have potential applicability in manufacturing FDM filaments for the 3D printing of metallic parts. Small amplitude oscillatory shear (SAOS) tests, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) demonstrate complex relationships among polydopamine coating, filler content, morphology, and rheological properties of the ABS/PEW/Cu system. Furthermore, PEW affects the interface adhesion and shear transmission between the ABS copolymer and the copper filler coated with polydopamine. Also, the polydopamine influences the rheological parameters of the polymer composites, namely retardation and relaxation times, melt flow, and cohesive energy density (Ec).

A potential active rheology control approach for 3D printable cement-based materials: Coupling of temperature and viscosity modifiers

Recently, the active rheology control for 3D printable cement-based materials (3DPCM) has gained increasing attention due to the challenging rheological requirements during printing. Inspired by the influences of polymers on the temperature sensitivity of rheological properties, here we propose a concept of active rheology control for 3DPCM coupling temperature control with the utilization of viscosity modifiers. Firstly, the rheological properties associated with 3D printing in response to a temperature range from 5 °C to 45 °C were investigated through flow curve, stress growth and small-amplitude oscillatory shear tests. Subsequently, total organic carbon and isothermal calorimetry tests were performed to further analyze the mechanism. Finally, validation 3D printing tests were conducted. Results indicate that increasing temperature improves the efficacy of hydroxypropyl methylcellulose and polycarboxylate ether-based superplasticizer through accelerated dissolution and adsorption, and enhanced chain stretching, thus allowing for an intensified or a suppressed response to temperature in the apparent viscosity, thixotropic area, static yield stress and storage modulus of 3DPCM. Increasing temperature also compensates for the delay in cement hydration due to the addition of polymers. Printing experiments provide preliminary evidence of the feasibility of active rheology control for 3DPCM through coupling between temperature and viscosity modifiers to improve the printability. The thickness ratio and width ratio of top layers to bottom layers of 3DPCM with HPMC were 1.46 and 0.84 when printed at 25 °C, which are 14.1% lower and 58.3% higher compared to that printed at 15 °C.

Effects of different salt ions on the structure and rheological behavior of sulfated cellulose nanocrystal hydrogel

Cellulose nanocrystal (CNC) hydrogels are increasingly used in various applications. Here, CNC hydrogels were formed by adding four salt ions (NaCl, KCl, MgCl2, and CaCl2) to sulfated CNC suspensions. NaCl and KCl are monovalent salt ions and MgCl2 and CaCl2 are divalent salt ions; each pair has similar cation charges but different cation radii. This study compared the effects of four salt ions on the structure and rheological behavior of CNC hydrogels. At the same ion concentration, compared with NaCl and KCl, the addition of MgCl2 and CaCl2 significantly reduced the distance between the CNC particles, forming pronounced aggregates and denser network structures. Furthermore, the G′ and G″ of the CNC hydrogels with salt ions followed the order NaCl < KCl < MgCl2 < CaCl2 in the small-amplitude oscillatory shear (SAOS) test, and more viscoelastic hydrogels exhibited relatively lower deformability in the creep-recovery test. Under large-amplitude oscillatory shear (LAOS) conditions, the CNC hydrogels with salt ions exhibited LAOS type III behavior, and the change in yield stress followed the same order as the SAOS results. Among them, CNC hydrogel with CaCl2 exhibited stronger nonlinear response and enhanced strain-stiffening behavior (higher I3/I1 and e3/e1) to resist deformation before 20% strain, as well as an enhanced softening effect (higher |v3/v1|) as the structure was destroyed and rearranged at strains ranging from 20% to 100%. Such CNC hydrogels with different salt ions, which can regulate structural and rheological properties, provide basis for designing hydrogels and meet potential requirements in food and biomedicine fields.

Effect of cellulose ether emulsion and oleogel as healthy fat alternatives in cream cheese. Linear and nonlinear rheology, texture and sensory properties

The suitability of oil-in-water (o/w) hydroxypropyl methylcellulose (HPMC)-based emulsions and oleogels to reduce total fat and saturated fat content in cream cheese was studied. The effect of HPMC emulsions and oleogels on spreadability, viscoelasticity, and sensory acceptability of cream cheese was evaluated. Small-amplitude oscillatory shear (SAOS) and large-amplitude oscillatory shear (LAOS) tests were performed to investigate linear and nonlinear rheology. All cheeses showed a predominance of G’ versus G” with a light dependence of both moduli with frequency in the linear viscoelastic region (LVR). Fat replacement with emulsion or oleogel significantly reduces the values of G’ and G” at the LVR, yield point, and flow point, and increases spreadability. This effect was greatest for the oleogel substitution. However, incorporation of emulsion or oleogel did not significantly affect tan δ, yield stress, yield strain, flow stress, and flow strain. The elastic and viscous evolution during the transition from SAOS to LAOS was similar in all cheeses, despite their differences in spreadability. At large deformation, all samples showed strain-stiffening and shear-thinning behavior. Similar sensory acceptability was found among the oleogel and emulsion cheeses and the control. The similar nonlinear rheological properties among cheeses do not explain the differences in spreadability properties, but explain their similar sensory acceptability. Furthermore, the purchase intention for oleogel and emulsion cheeses increases when consumers receive information on the type and amount of fat.

Rheological Characterization of Gofio and Aloe Vera Blended Juice

Considering that gofio (Gf) and aloe vera juice (AVJ) have very good nutritional qualities, their combination is proposed because it is indicated as an easy and fast source of basic bio-elements. The texture of a food must be accepted by customers. This means that the rheological characteristics of the product must be known and controlled. Therefore, the influence of Gf concentration on the rheological behavior of Gf/AVJ suspensions must be determined. With continuous shear experiments, the purely viscous response of a material can be obtained. AVJ and Gf/AVJ suspensions showed shear-thinning behavior. The ability of Gf particles and aggregates to distort the flow field was quantified determining the intrinsic viscosity η of the suspensions at several shear rates using Krieger–Dougherty equation. The results indicated that the shape and size of Gf aggregates is not affected by the mechanical action due to shear. The power law (Ostwald–de Waele) model fitted the experimental steady viscosity versus shear rate values (steady viscosity curves). The flow index was less than 1, which corresponded to shear-thinning behavior. It was obtained that the flow index of AVJ maintained unaltered despite the presence of Gf particles. However, the viscosity value increased with the increasing amount of Gf as it was expected. The viscoelastic behavior of the microstructure at rest of the AVJ and Gf/AVJ suspensions was studied using oscillatory shear tests. First, linear viscoelastic response was confirmed in the relatively low amplitude shear region γ0&lt;0.001 using an amplitude sweep shear test. After that, frequency sweep shear tests were conducted in the region where Gf/AVJ suspensions showed linear viscoelastic behavior. Varying the frequency, the response of the microstructure at rest of the suspensions when the mechanical action lasts from short to long time interval can be characterized. Jeffreys mechanical model was used for the analysis of the LVE response of Gf/AVJ suspensions. Using small amplitude oscillatory shear (SAOS) tests, it was obtained that Gf/AVJ suspensions are viscoelastic liquids that change their texture from chewy to creamy when the Gf concentration increases.

Rheology and 3D printing characteristics of heat-inducible pea protein-carrageenan-glycyrrhizic acid emulsions as edible inks

Protein-based emulsion gels, especially those induced by heat, have been widely used in food 3D printing. However, the rheology and texture of protein-based gels are important factors restricting 3D printing. In this study, glycyrrhizic acid (GA) was used to improve the rheology properties of pea protein (PP)-Kappa carrageenan (κCA) composite emulsion inks, and the suitability of these inks for extrusion 3D food printing was investigated. The results showed that all emulsion inks have shear thinning behavior and could be smoothly extruded during 3D printing. Herschel-Bulkley model fitting results proved that with the increase of PP concentration (from 5% to 10%), the yield stress (σ0) increased from 15.4 to 28.19 Pa, and the consistency coefficient (k) increased from 1.09 to 2.66 Pa.sn. The objects printed with 10% PP-GA0.3 inks showed excellent self-supporting capability, a smooth surface texture, and high printing accuracy. Emulsion inks had good temperature stability and could form emulsion gels following heat induction. The results of small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) tests confirmed that the addition of GA improved the strength of the gels. This research provides valuable insights for the advancement of food 3D printing inks.

The rheology of saltwater taffy

Saltwater taffy, an American confection consisting of the main ingredients sugar, corn syrup, water, and oil, is known for its chewy texture and diverse flavors. We use a small amplitude oscillatory shear test to probe the linear viscoelastic properties of commercial taffy. At low frequencies, self-similar relaxation behavior characteristic of a critical gel is observed. The storage and loss moduli are power-law functions, with the same exponent, of the frequency. Such self-similarity arises from the distribution of air bubbles and oil droplets in the taffy, where air is incorporated and oil is emulsified through an iterative folding process known as “taffy-pulling.” Taffy obeys the time–temperature superposition principle. Horizontally shifting the dynamic moduli obtained at different temperatures yields a master curve at a chosen reference temperature. As a sufficiently high frequency is exceeded, taffy transitions from a critical gel-like state to an elastic solid-like state. The master curve can be described by the fractional Maxwell gel (FMG) model with three parameters: a plateau modulus, a characteristic relaxation time, and a power-law exponent. The master curves for taffy of different flavors can all be described by the FMG model with the same exponent, indicating that minor ingredients like flavorings and colorings do not significantly affect the rheology of taffy. Scaling the master curves with the plateau modulus and relaxation time results in their collapse onto a supermaster curve, hinting at a more fundamental time–temperature–taffy superposition principle. Guided by this principle, we hand-pull lab-made model taffies successfully reproducing the rheology of commercial taffy.

Effect of nano-metakaolin on establishment of internal structure of fly ash cement paste

The study aims to enhance the viscosity and establishment of internal structure of fly ash (FA) cement paste through the addition of nano-metakaolin (NMK). Various tests, including apparent viscosity test, small amplitude oscillatory shear test, and calorimetric test, were conducted to investigate the effects of FA content, NMK content, superplasticizer content, and test temperature. The results showed that NMK increased the apparent viscosity of FA cement paste while weakening its shear thinning behavior. Specifically, incorporating 5 wt% NMK increased the apparent viscosity of cement paste containing 30 wt% FA by 60%. Furthermore, NMK accelerated the growth of storage modulus (G') and facilitated the rapid establishment of internal structure in FA cement paste, the optimal amount of NMK admixture in a 30 wt% FA cement paste is determined to be 5 wt%. However, the presence of superplasticizer hindered the increase in G' and delayed the establishment of internal structure in NMK/FA cement pastes. For cement paste containing 5 wt% NMK and 30 wt% FA, the growth rate of G' within 60 min decreased to 26% when 0.12 wt% superplasticizer was added compared to the cement paste without superplasticizer. Temperature had a significant impact on the establishment process of internal structure in NMK/FA cement pastes within 90 min but had minimal effect on the final state at 90min. For N5FA30 cement paste hydrated for 30 min and 90 min respectively, G' at 10 °C was approximately 7.3% and 66.7% compared to that at 40 °C. Moreover, a power function correlation was observed between G' and cumulative hydration heat per gram of cement (Hc) in NMK/FA cement pastes. The inclusion of superplasticizer decreased both G' and Hc in the cement paste. Notably, the influence of superplasticizer on G' was more pronounced than its impact on Hc during the hydration process.

Viscoelastic behavior of oral mucosa. A rheological study using small-amplitude oscillatory shear tests

The purpose of this work was to determine the viscoelastic behavior of porcine and human oral mucosa under physiological conditions of temperature, hydration and chewing. The linear elastic and viscous shear moduli of these soft tissues were determined by small-amplitude oscillatory shear (SAOS) tests at masticatory frequency using a stress-controlled rheometer equipped with an immersion cell on punched biopsies 8 mm in diameter. Non physiological conditions of temperature were also used to access other parameters such as the denaturation temperature of collagen.First, the different parameters such as normal force, frequency and maximal strain were adjusted to obtain reliable data on porcine mucosa. The optimal normal force was 0.1N and the linear viscoelastic limit was found for a strain amplitude of 0.5% for both 0.1 and 1 Hz. The storage moduli of porcine mucosa, ranging from 5 to 16 kPa, were in the same range as cutaneous tissues determined by SAOS at equivalent frequencies. The storage modulus, superior to the loss modulus G″, indicates a predominant elastic contribution to shear stress in chewing conditions.Second, this protocol evidenced an influence of the anatomic site of the mouth on the viscoelastic behavior of porcine mucosa, mandibular biopsies having higher storage moduli than maxillary biopsies. Temperature scans showed the mechanical manifestation of collagen denaturation in the 60–70 °C range as previous calorimetric analyses. Finally, this mechanical protocol was successfully adapted to characterize human mucosa in an elderly population. It was shown that the elastic modulus is impacted by local inflammation (gingivitis), decreasing significantly from 6 ± 1.4 kPa to 2.5 ± 0.3 kPa.

Rheological Performance of High-Temperature-Resistant, Salt-Resistant Fracturing Fluid Gel Based on Organic-Zirconium-Crosslinked HPAM

Development of low-cost, high-temperature-resistant and salt-resistant fracturing fluids is a hot and difficult issue in reservoir fluids modification. In this study, an organic zirconium crosslinker that was synthesized and crosslinked with partially hydrolyzed polyacrylamide (HPAM) was employed as a cost-effective polymer thickener to synthesize a high-temperature-resistant and salt-resistant fracturing fluid. The rheological properties of HPAM in tap water solutions and 2 × 104 mg/L salt solutions were analyzed. The results demonstrated that addition of salt reduced viscosity and viscoelasticity of HPAM solutions. Molecular dynamics (MD) simulation results indicated that, due to electrostatic interaction, the carboxylate ions of HPAM formed an ionic bridge with metal cations, curling the conformation, decreasing the radius of rotation and thus decreasing viscosity. However, optimizing fracturing fluids formulation can mitigate the detrimental effects of salt on HPAM. The rheological characteristics of the HPAM fracturing fluid crosslinking process were analyzed and a crosslinking rheological kinetic equation was established under small-amplitude oscillatory shear (SAOS) test. The results of a large-amplitude oscillation shear (LAOS) test indicate that the heating effect on crosslinking is stronger than the shear effect on crosslinking. High-temperature-resistant and shear-resistant experiments demonstrated good performance of fracturing fluids of tap water and salt solution at 200 °C and 180 °C.

Super stable Melaleuca alternifolia essential oil Pickering emulsions stabilized with cellulose nanofibrils: Rheological aspects

Melaleuca alternifolia essential oil (MaEO) has attracted technological interest in the pharmaceutical, cosmetic and food sectors for its outstanding and broad antimicrobial spectra. However, its active components are highly susceptible to oxidation due to weathering. Therefore, stabilization of the MaEO components is essential. In this work, we evaluated the stability and rheology of MaEO-in-water Pickering emulsions using cellulose nanofibrils (CNF) as an eco-friendly and sustainable stabilizing agent. Small amplitude oscillatory shear (SAOS) tests brought exciting information about the relationship between internal microstructure strength and the relaxation processes, retardation processes, and viscous flow behavior of the emulsions. Measurements of oil droplet diameter distribution and steady-state rheological tests indicate that the emulsions have super stability under static environmental conditions within 28 storage days. Also, the emulsions present steady-state viscosity suitable for applications in dysphagic foods, presenting a pronounced shear-thinning behavior appropriate to developing cream and lotion skin-care eco-friendly products for the human body.

Effect of the Welan Gum Concentration on the Rheological and Structural Behaviour of Biocomposite Hydrogels with Sepiolite as Filler.

A very positive and effective approach to tuning the mechanical properties of polymers has been the development of composites. This paper deals with novel biocomposite hydrogels composed by two biocompatible materials: welan gum as biopolymer matrix and sepiolite as filler. Welan gum content was studied as a tuning parameter to control the rheological properties of the developed biocomposites. The rheological and microstructural behaviour of the composites was investigated by mean of steady-state flow curves, creep-recovery tests, small amplitude oscillatory shear tests, and electron microscopy. An increase in welan gum content provoked the progressive disappearance of the shear-thinningzero-shear-thinning behaviour with a yield point which was clearly defined, characteristic of sepiolite gels, leading to a conventional shear-thinning behaviour, typical of polymeric systems. Also, a higher content of biopolymer in the mixtures led to a more elastic and compact structure characterized by higher values of both G' and G". The fundamental novelty was based on taking the flowability provided by the biopolymer as the main objective and reinforcing the viscosity yielded by welan gum with sepiolite, which contributed to increasing the biocomposite consistency. Thus, rheological properties can be adjusted, taking into account the balance of the components to adapt them to the requirements of each application.

Hemicellulose-bacterial cellulose ribbon interactions affect the anisotropic mechanical behaviour of bacterial cellulose hydrogels

The aim of this study is to investigate the effect of hemicellulose-cellulose interactions on the anisotropic structure of the bacterial cellulose (BC) ribbon network. BC-arabinoxylan (BC-AX) and BC-mixed linkage glucan (BC-MLG) composites were prepared. The mechanical/rheological behaviour was evaluated by compression combined with small amplitude oscillatory shear (SAOS) and stress-relaxation tests. Microscopy revealed that the BC ribbons tended to orient parallel to the liquid/air interface. AX and MLG gathered on the surface of cellulose ribbons but had limited influence on the crystallinity of BC. BC hydrogels showed direction-dependent mechanical properties in compression and stress-relaxation tests. The peak compressive modulus of the tangential BC sample (compressed towards the side of the sample) was over 1000 kPa, whereas for the normal sample (compressed towards the top of sample) the value was only 280 kPa. The relaxation ability of the tangential sample was 48% lower than the normal sample at 1% compression ratio. AX and MLG reduced the anisotropic behaviour of the native BC in normal/tangential compression and stress-relaxation tests, especially in the highly-compressed composites. However, the rheological behaviour of BC and the composites was comparatively isotropic in SAOS. This study is beneficial for further understanding of the contribution of hemicelluloses to the mechanical properties of BC hydrogels, and may promote the application of BC-based materials in food and medical industries.

Influence of Type and Concentration of Biopolymer on β-Carotene Encapsulation Efficiency in Nanoemulsions Based on Linseed Oil.

Many lipophilic active substances, such as β-carotene, are sensitive to chemical oxidation. A strategy to protect these ingredients is encapsulation using nanoemulsions. This work analyzes the relationship between the physical stability and encapsulation efficiency of nanoemulsions based on linseed oil. The role of two different polysaccharides, Advanced Performance xanthan gum (APXG) or guar gum (GG) as stabilizers at different concentrations were studied to reach the required physical stability of these systems. This was investigated by means of droplet size distributions, steady-state flow curves, small amplitude oscillatory shear tests, multiple light scattering, and electronic microscopy. The overall results obtained reveal a depletion flocculation mechanism in all the APXG nanoemulsions, regardless of the concentration, and above 0.3 wt.% for GG nanoemulsions. Moreover, it has been demonstrated that enhanced physical stability is directly related to higher values of encapsulation efficiency. Thus, the nanoemulsion formulated with 0.2 wt.% GG, which presented the lowest creaming degree conditioned by depletion flocculation, showed a relative β-carotene concentration even above 80% at 21 days of aging time. In conclusion, the adequate selection of polysaccharide type and its concentration is a key point for the application of stable nanoemulsions as vehicles for active ingredients.

Insights into the viscoelastic properties of cement paste based on SAOS technique

Understanding the viscoelastic properties of cement paste is beneficial to pumping, formwork casting and 3D printing of cement-based materials. This paper presents new insights into the viscoelastic properties of cement paste with various compositions. Several parameters, including critical strain, storage modulus and viscoelastic yield stress obtained from small amplitude oscillatory shear (SAOS) test, are selected to characterize the viscoelasticity of fresh cementitious paste. Results reveal that increasing water-to-cement (w/c) ratio reduces the storage modulus at linear viscoelastic region (LVER) and viscoelastic yield stress of cement paste, whereas higher w/c increases the critical strain. The replacement of cement by fly ash has no significant influence on the critical strain of cement paste. Due to the improvement of cohesive bonding between cement particles by nanoparticles, the incorporation of nano-Fe3O4 particles results in an increase in the storage modulus at LVER, critical strain and viscoelastic yield stress. The critical strain of cement paste gradually increases with the concentration of polycarboxylate ether (PCE) superplasticizer, which possibly can be attributed to the interactions and entanglement of PCE molecules adsorbed onto the solid particles. By contrast, cement pastes with low PCE additions exhibit an increase in the viscoelastic yield stress, while higher PCE additions significantly decrease the storage modulus at LVER and viscoelastic yield stress of cement paste.

Influence of protein ratios on the structure and gel properties of soybean-wheat co-precipitated proteins

Co-precipitation is a method of combining proteins that can improve the defects of a single protein while also improving its functional properties. The effect of protein ratios on the structure and gelation of co-precipitated prepared with soy protein isolate (SPI) and wheat protein (WP) was investigated in this study. Structural analysis revealed that co-precipitation triggered sheet-helix transitions of SPI and WP, exposing hydrophilic groups and embedding hydrophobic moieties. The water dispersibility of the soybean-wheat co-precipitated protein (SWCP) was significantly improved (p < 0.05). Furthermore, when compared to the protein blend, the effect of co-precipitation was more significant. Small amplitude oscillatory shear tests revealed that the interaction between SPI and WP altered the gel formation temperature and increased gel elasticity. Co-precipitated protein resulted in denser and more homogenous gel networks with very strong inter-floc links, as well as increased water holding capacity and gel strength. According to the findings, co-precipitation may be a simple and practical method for modifying proteins to improve their functional properties.

Development of soy protein isolate emulsion gels as extrusion-based 3D food printing inks: Effect of polysaccharides incorporation

Soy protein isolate (SPI) emulsion gel inks with polysaccharides of guar gum (GG) or xanthan gum (XG) for extrusion-based three-dimensional (3D) printing were investigated. The effects of the polysaccharide type and concentration on the printability, rheological properties, and microstructure of inks were discussed. Results indicated that the 3D printed products of SPI-GG0.5 inks demonstrated low dimensional printing deviation with great self-supporting capability and smooth and slightly flawed surface texture, while SPI-XG0.5 inks had the highest hardness and rough surface texture. The results of small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) test proved that SPI-XG0.5 inks exhibited the maximal gel strength, providing its 3D printed products with highest hardness. Secondary loops of Lissajous plots wouldn't emerge in SPI-XG0.5 inks, indicating decreased network flexibility and slightly larger dimensional printing deviation. The microstructure and fourier transform infrared (FTIR) analysis suggested the interaction of SPI with XG was stronger than that of GG due to hydrogen bonding and electrostatic interactions. When the XG concentration reached 0.5%, the network structure of the inks was changed, resulting in a rough surface texture of the 3D printed product. There are few studies on 3D printing of SPI emulsion gels, and this research offers more possibilities for the development of 3D printing inks.

Enhanced dispersion stability and interfacial damping of POSS-functionalized graphene oxide in PDMS nanocomposites

Polyhedral oligomeric silsesquioxane (POSS) functionalized graphene oxide (GO) is prepared to improve the dispersity of GO nanofillers in a polydimethylsiloxane matrix. Improved interfacial affinity of the GO-POSS with a polymer matrix is characterized by a small amplitude oscillatory shear test. We confirm that the POSS-functionalized GO induces better filler dispersibility and less filler aggregation in the matrix, resulting in enhanced elasticity in the solution. After curing, the POSS interface works as a soft and lubricating layer at the interface, which enhances interfacial damping within the nanocomposites.