Design of a Functional Pea Protein Matrix for Fermented Plant-Based Cheese

The production of a fermented plant-based cheese requires understanding the behavior of the selected raw material prior to fermentation. Raw material processing affects physicochemical properties of plant protein ingredients, and it determines their ability to form fermentation-induced protein gels. Moreover, the addition of oil also influences structure formation and therefore affects gel firmness. This study focuses on identifying and characterizing an optimal pea protein matrix suitable for fermentation-induced plant-based cheese. Stability and gel formation were investigated in pea protein matrices. Pea protein isolate (PPI) emulsions with 10% protein and 0, 5, 10, 15, and 20% olive oil levels were produced and further fermented with a starter culture suitable for plant matrices. Emulsion stability was evaluated through particle size, ζ-potential, and back-scattered light changes over 7 h. Gel hardness and oscillation measurements of the fermented gels were taken after 1 and 7 days of storage under refrigeration. The water-holding capacity of the gels was measured after 7 days of storage and their microstructure was visualized with confocal microscopy. Results indicate that all PPI emulsions were physically stable after 7 h. Indeed, ζ-potential did not change significantly over time in PPI emulsions, a bimodal particle size distribution was observed in all samples, and no significant variation was observed after 7 h in any of the samples. Fermentation time oscillated between 5.5 and 7 h in all samples. Higher oil content led to weaker gels and lower elastic modulus and no significant changes in gel hardness were observed over 7 days of storage under refrigeration in closed containers. Water-holding capacity increased in samples with higher olive oil content. Based on our results, an optimal pea protein matrix for fermentation-induced pea protein gels can be produced with 10% protein content and 10% olive oil levels without compromising gel hardness.

Effects of High-Intensity Ultrasound Pretreatment on Structure, Properties, and Enzymolysis of Walnut Protein Isolate

The purpose of this paper was to investigate the effect of high-intensity ultrasonication (HIU) pretreatment before enzymolysis on structural conformations of walnut protein isolate (WPI) and antioxidant activity of its hydrolysates. Aqueous WPI suspensions were subjected to ultrasonic processing at different power levels (600–2000 W) and times (5–30 min), and then changes in the particle size, zeta (ζ) potential, and structure of WPI were investigated, and antioxidant activity of its hydrolysates was determined. The particle size of the particles of aqueous WPI suspensions was decreased after ultrasound, indicating that sonication destroyed protein aggregates. The ζ-potential values of a protein solution significantly changed after sonication, demonstrating that the original dense structure of the protein was destroyed. Fourier transform infrared spectroscopy indicated a change in the secondary structure of WPI after sonication, with a decrease in β-turn and an increase in α-helix, β-sheet, and random coil content. Two absorption peaks of WPI were generated, and the fluorescence emission intensity of the proteins decreased after ultrasonic treatment, indicating that the changes in protein tertiary structure occurred. Moreover, the degree of hydrolysis and the antioxidant activity of the WPI hydrolysates increased after sonication. These results suggest that HIU pretreatment is a potential tool for improving the functional properties of walnut proteins.

Interaction of surfactants with poloxamers 338 and its effect on some properties of cream base

The aim. Study of the interaction of surfactants with poloxamer 338 (P338) and the effect of P338 on the properties of cream bases. Materials and methods. Solutions of the surfactants and P338 as well as cream bases were under study. The average hydrodynamic diameter (Dh) and zeta potential (ζ‑potential) were determined by the light scattering intensity and electrophoretic mobility of micelles. The electron paramagnetic resonance (EPR) spectra of spin probes in micelles, solvents and bases were obtained; the type of spectrum, isotropic constant (AN), rotational correlation times (τ) and anisotropy parameter (ε) were determined. Liquids and cream bases were studied by capillary and rotational viscometry; the flow behaviour and yield stress (t0), dynamic and apparent viscosity (η) as well as the hysteresis (thixotropic) area (AH) were determined. The microstructure of the bases was examined by optical microscopy. The strength of adhesion (Sm) was assessed by the pull-off test, and the absorption of water was studied by dialysis. Results. Under the impact of P338 the hydrodynamic diameters of micelles formed by cationic, anionic and nonionic surfactants decreased as well as the absolute values of their ζ‑potential became lower, but the microviscosity of the micelle nuclei increased. There was also a change in the structure of the aggregates of surfactant with fatty alcohols; EPR spectra, which were superpositions characteristic for the lateral phase separation, converted into triplets that indicated the uniform distribution of lipophilic probes in the surfactant phase. When the content of P338 increased to 17 %, the rheological parameters of the bases increased drastically, the flow behaviour and the microstructure changed. The bases had the consistency of cream within temperature range from 25 °C to 70 °C and completely restored their apparent viscosity, which had decreased under shear stress. P338 enhances the adhesive properties of the bases. Due to their microstructure, cream bases have a lower ability to absorb water compared to a solution and gel containing 17 % and 20 % P338, respectively. Conclusions. The structure of surfactant micelles and aggregates of surfactants with fatty alcohols changed under impact of P338 due to the interaction of surfactants with P338. As a result of this interaction, at a sufficiently high concentration of P338, the microstructure and flow behaviour of bases changed, their rheological parameters, which remain high at temperatures from 25 °C to 70 °C, increased significantly, and water absorption parameters decreased. The bases with P338 were more adhesive

Advancement of Measurement Techniques for Tunable Resistive Pulse Sensing

<p>Tunable resistive pulse sensing (TRPS) is a particle-by-particle analysis technique combining the Coulter principle with size-tunable pores. TRPS can be used to characterize biological and synthetic particles 50 nm - 20 µm in diameter. Information is obtained from the resistive pulse signal, a transient change in ionic current observed when a particle passes through the pore. TRPS has been shown to provide excellent resolution and accuracy for measuring particle size and concentration as well as providing information about particle charge. TRPS is therefore applicable to many industrial and fundamental research areas involving aptamers, drug delivery particles, extracellular vesicles and other biological particle types. Advancement of this technology requires a better understanding of the technique, particularly in the area of particle surface charge measurement and this Thesis helps to provide that understanding. In this work, firstly particle ζ-potential measurement using TRPS was investigated. A number of different measurement methods are presented and the uncertainties associated with each method are outlined. The ζ-potential for a variety of particles with different surface charges were measured in a range of electrolytes. Particle ζ-potential measurements were then improved upon with the addition of streaming potential measurements to measure the pore surface charge. The ζ-potential of the pore surface, which makes a significant contribution to particle ζ-potential calculations, was measured using a set up which works alongside the qNano. Streaming potential measurements were also used to investigate changes in the pore surface charge following application of number of different chemical coatings. The volume of data collected and detail of analysis in this work (including uncertainties) is unprecedented in TRPS ζ potential measurements. Biphasic pulses arising from the charge on the particles were investigated. The pulse is conventionally resistive, but biphasic pulses which include both resistive and conductive components are significant for less than 50 mM salt concentrations when measuring 200 nm particles. The experimental variables investigated include the concentration of the electrolyte, particle charge, pore size, applied voltage, and the direction of particlemotion. Conductive pulse size was seen to decrease with increasing electrolyte concentration and pore size and increase with applied voltage. A linear relationship was found between conductive pulse magnitude and particle surface group density. The influence of direction of motion on conductive pulses was consistent with concentration polarization of an ion selective pore. Biphasic pulses were also seen to affect conventional TRPS particle size measurements. Finally, size distribution broadening due to varying particle trajectories was investigated. Pulse size distributions for monodisperse particles became broader when the pore size was increased and featured two distinct peaks. Relatively large pulses are produced by particles with trajectories passing near to the edge of the pore. Other experiments determined that pulse size distributions are independent of applied voltage but broaden with increasing pressure applied across the membrane.</p>

Advancement of Measurement Techniques for Tunable Resistive Pulse Sensing

<p>Tunable resistive pulse sensing (TRPS) is a particle-by-particle analysis technique combining the Coulter principle with size-tunable pores. TRPS can be used to characterize biological and synthetic particles 50 nm - 20 µm in diameter. Information is obtained from the resistive pulse signal, a transient change in ionic current observed when a particle passes through the pore. TRPS has been shown to provide excellent resolution and accuracy for measuring particle size and concentration as well as providing information about particle charge. TRPS is therefore applicable to many industrial and fundamental research areas involving aptamers, drug delivery particles, extracellular vesicles and other biological particle types. Advancement of this technology requires a better understanding of the technique, particularly in the area of particle surface charge measurement and this Thesis helps to provide that understanding. In this work, firstly particle ζ-potential measurement using TRPS was investigated. A number of different measurement methods are presented and the uncertainties associated with each method are outlined. The ζ-potential for a variety of particles with different surface charges were measured in a range of electrolytes. Particle ζ-potential measurements were then improved upon with the addition of streaming potential measurements to measure the pore surface charge. The ζ-potential of the pore surface, which makes a significant contribution to particle ζ-potential calculations, was measured using a set up which works alongside the qNano. Streaming potential measurements were also used to investigate changes in the pore surface charge following application of number of different chemical coatings. The volume of data collected and detail of analysis in this work (including uncertainties) is unprecedented in TRPS ζ potential measurements. Biphasic pulses arising from the charge on the particles were investigated. The pulse is conventionally resistive, but biphasic pulses which include both resistive and conductive components are significant for less than 50 mM salt concentrations when measuring 200 nm particles. The experimental variables investigated include the concentration of the electrolyte, particle charge, pore size, applied voltage, and the direction of particlemotion. Conductive pulse size was seen to decrease with increasing electrolyte concentration and pore size and increase with applied voltage. A linear relationship was found between conductive pulse magnitude and particle surface group density. The influence of direction of motion on conductive pulses was consistent with concentration polarization of an ion selective pore. Biphasic pulses were also seen to affect conventional TRPS particle size measurements. Finally, size distribution broadening due to varying particle trajectories was investigated. Pulse size distributions for monodisperse particles became broader when the pore size was increased and featured two distinct peaks. Relatively large pulses are produced by particles with trajectories passing near to the edge of the pore. Other experiments determined that pulse size distributions are independent of applied voltage but broaden with increasing pressure applied across the membrane.</p>

Adsorption Capacities of Iron Hydroxide for Arsenate and Arsenite Removal from Water by Chemical Coagulation: Kinetics, Thermodynamics and Equilibrium Studies

Arsenic (As)-laden wastewater may pose a threat to biodiversity when released into soil and water bodies without treatment. The current study investigated the sorption properties of both As(III, V) oxyanions onto iron hydroxide (FHO) by chemical coagulation. The potential mechanisms were identified using the adsorption models, ζ-potential, X-ray diffraction (XRD) and Fourier Transform Infrared Spectrometry (FT-IR) analysis. The results indicate that the sorption kinetics of pentavalent and trivalent As species closely followed the pseudo-second-order model, and the adsorption rates of both toxicants were remarkably governed by pH as well as the quantity of FHO in suspension. Notably, the FHO formation was directly related to the amount of ferric chloride (FC) coagulant added in the solution. The sorption isotherm results show a better maximum sorption capacity for pentavalent As ions than trivalent species, with the same amount of FHO in the suspensions. The thermodynamic study suggests that the sorption process was spontaneously exothermic with increased randomness. The ζ-potential, FT-IR and XRD analyses confirm that a strong Fe-O bond with As(V) and the closeness of the surface potential of the bonded complex to the point of zero charge (pHzpc) resulted in the higher adsorption affinity of pentavalent As species than trivalent ions in most aquatic conditions. Moreover, the presence of sulfates, phosphates, and humic and salicylic acid significantly affected the As(III, V) sorption performance by altering the surface properties of Fe precipitates. The combined effect of charge neutralization, complexation, oxidation and multilayer chemisorption was identified as a major removal mechanism. These findings may provide some understanding regarding the fate, transport and adsorption properties onto FHO of As oxyanions in a complex water environment.

Colloidal characteristics of gelatin-treated clay: Intercalation, stability, wettability, and rheological properties

In this paper, sodium montmorillonite was modified with gelatin of different concentrations, and various colloidal characteristics of the gelatin-treated clays were measured and analyzed in detail. First, the influence of gelatin on the interlayer space of Mt layers was investigated by X-ray diffraction analysis. Moreover, the aggregation of Mt particles was examined using a combination of electron microscopy and particle size distribution experiments, while the variation of the electrical property of Mt was measured using ζ potential test. Gelatin of different concentrations can increase the particle size of Mt in different degrees. The addition of 4% gelatin could improve the ζ potential of Mt from −30.65 to −15.55 mV. The wettability change of modified Mt induced by the adsorption of gelatin was followed by measurements of water contact angle and observations of the morphology of Mt/gelatin membrane through SEM images. 4% gelatin could improve the water contact angle of Mt to 81.3°. Finally, the rheological properties of Mt/gelatin dispersion including shear viscosity and shear stress were measured using a stress-controlled rheometer. All of the results were consistent by showing that the overall colloidal characteristics and behavior of the gelatin-treated Mt strongly varied depending on the gelatin concentration used in the modification process. These results can provide a deep and comprehensive understanding of the colloidal properties of clay/gelatin systems and give important guidance for the performance design and improvement of Mt/gelatin composite materials. Furthermore, this study can also be expanded the application of gelatin and its composites to other fields.

An Experimental Study of Improving Viscous Oil Recovery by Using Hybrid Enhanced Oil Recovery Techniques: A Case Study of Alaska North Slope Reservoir

Summary Shallow reservoirs on the Alaska North Slope (ANS), such as Ugnu and West Sak-Schrader Bluff, hold approximately 12 to 17 × 109 barrels of viscous oil. Because of the proximity of these reservoirs to the permafrost, feasible nonthermal enhanced oil recovery (EOR) methods are highly needed to exploit these oil resources. This study proposes three hybrid nonthermal EOR techniques, including high-salinity water (HSW) injection sequentially followed by low-salinity water (LSW) and low-salinity polymer (LSP) flooding (HSW-LSW-LSP), solvent-alternating-LSW flooding, and solvent-alternating-LSP flooding, to recover ANS viscous oils. The oil recovery performance of these hybrid EOR techniques has been evaluated by conducting coreflooding experiments. Additionally, constant composition expansion (CCE) tests, ζ potential determinations, and interfacial tension (IFT) measurements have been conducted to reveal the EOR mechanisms of the three proposed hybrid EOR techniques. Coreflooding experiments and IFT measurements have been conducted at reservoir conditions of 1,500 psi and 85°F, while CCE tests have been carried out at a reservoir temperature of 85°F. ζ potential determinations have been conducted at 14.7 psi and 77°F. The coreflooding experiment results have demonstrated that all of the three proposed hybrid EOR techniques could result in much better performance in reducing residual oil saturation than waterflooding and continuous solvent flooding in viscous oil reservoirs on ANS, implying better oil recovery potential. In particular, severe formation damage or blockage at the production end occurred when natural sand was used to prepare the sandpack column, indicating that the natural sand may have introduced some unknown constituents that may react with the injected solvent and polymer, resulting in a severe blocking issue. Our investigation on this is ongoing, and more detailed studies are being conducted in our laboratory. The CCE test results demonstrate that more solvent could be dissolved into the tested viscous oil with increasing pressure, simultaneously resulting in more oil swelling and viscosity reduction. At the desired reservoir conditions of 1,500 psi and 85°F, as much as 60 mol% of solvent could be dissolved into the ANS viscous oil, resulting in more than 31% oil swelling and 97% oil viscosity reduction. Thus, the obvious oil swelling and significant viscosity reduction resulting from solvent injection could lead to much better microscopic displacement efficiency during the solvent flooding. The ζ potential determination results illustrate that LSW resulted in more negative ζ potential than HSW on the interface between sand and water, indicating that lowering the salinity of injected brine could result in the sand surface being more water-wet, but adding polymer to the LSW could not further enhance the water wetness. The IFT measurement results show that the IFT between the tested ANS viscous oil and LSW is higher than that between the tested viscous oil and HSW, which conflicts with the commonly recognized IFT reduction effect by LSW flooding. Thus, the EOR theory of the LSW flooding in our proposed hybrid techniques may be attributed to low-salinity effects (LSEs) such as multi-ion exchange, expansion of electrical double layer, and salting-in effect, while water wetness enhancement may benefit the LSW flooding process to some extent. The LSP’s viscosity is much higher than the viscosities of LSW and solvent, so LSP injection could result in better mobility control in the tested viscous oil reservoirs, leading to improvement of macroscopic sweep efficiency. Combining these EOR theories, the proposed hybrid EOR techniques have the potential to significantly increase oil recovery in viscous oil reservoirs on ANS by maximizing the overall displacement efficiency.

Redox/pH-Responsive Biodegradable Thiol-Hyaluronic Acid/Chitosan Charge-Reversal Nanocarriers for Triggered Drug Release

Biodegradable nanoparticles and micelles are promising nanosystems for the targeted delivery of potent anticancer drugs. By using specialized polymers as nanocarriers, targeted drug delivery and release can be developed. We developed thiol-hyaluronic acid (HA-SH)/chitosan (CS) nanoparticles with redox/pH dual-responsiveness via electrostatic self-assembly followed by spontaneous chemical cross-linking. The nanoparticle surface charges were reversible through different HA-SH and CS mass ratios. Doxorubicin (DOX) was used as a model drug. Dual cross-linked nanoparticles with diameters of approximately 300 nm exhibited superior stability under physiological conditions compared with nanoparticles without disulfide cross-linking. DOX was loaded more efficiently into negative nanoparticles (45.7 wt%) than positive nanoparticles (14.2 wt%). Drug release from negative nanoparticles (ζ potential of approximately −20) was higher (87.8 wt%) at pH 4.5 and in the presence of 10 mM glutathione. Positive nanoparticles (ζ potential of approximately +20) showed the same trend, but the release rate was slower than that of negative nanoparticles. DOX-loaded HA-SH/CS particles were taken up by human breast cancer cells (SKBR3), and the loaded drug was released, exhibiting potential antitumor efficacy. The HA-SH/CS nanoparticles in this study were stable under physiological conditions and are promising candidates for the targeted delivery and release of anticancer drugs.

Functional and technological properties of food additive "Magnetofood" in production of shaped jelly marmalade on agar and pectin

Jelly and marmalade products are "lyophilic colloids" – lyophilic colloidal-dispersed, ie microheterogeneous (multi- or polyphasic) systems based on high molecular weight compounds (gelatin, pectin, agar, etc.). Therefore, the problem of stabilizing their polyphasic structure is relevant. In addition, the expansion and improvement of the production of jelly and marmalade products requires the search for simplified resource- and energy-saving technology, increasing the stability of the colloidal disperse system, improving the quality and extending the shelf life of finished products. Promising technological applications have food additives in the nanometer range, due to specific and stable physical and chemical parameters, a wide range of functional and technological properties. The paper proposes the solution of the problem of stabilization of the polyphase structure of jelly-marmalade products and the formation of their quality by using the food additive "Magnetofood" (based on double oxide of divalent and trivalent iron: FeO×Fe2O3). "Magnetofood" - highly dispersed powder with a particle size (70–80) nm, which has a fairly diverse functional and technological potential: high ζ-potential and surface activity; clusterophilicity and amphiphilicity; complexing, thickening, structuring, stabilizing, thixotropic properties. This allows us to recommend "Magnetofood" as a food additive of complex action to improve the quality and prolong the shelf life of jelly-marmalade products, in particular jelly-shaped marmalade. The surface-active properties of nanoparticles of the food additive "Magnetofood" are determined: a rather significant value of ζ-potential (34-44) mV, amphiphilicity (marginal wetting angle Q<90o by polar-nonpolar medium) - show signs of stability and stability on polyphasic colloidal-dispersed systems , which increases in acidic environments, in solutions of polysaccharides, proteins on average by (55±)%, which is due to clusterophilicity and self-organization of nanoparticles "Magnetofood" into electrostatic complexes with proteins, polysaccharides and their spatial structuring. It was found that the addition of "Magnetofood" in the mass fraction (0,10–0,20)% to the mass of the structurant increases the viscosity of aqueous solutions of gelling agents in (1,22–1,27) times for agar and in (1,24–1,29) times for pectin and the rate of structuring of gel masses in (1,73±0,01) times for agar and in (1,67±0,01) times for pectin due to the structure-forming action of nanoparticles "Magnetofood". In addition, the ability of the gel structure to thixotropy increases by (1,4–1,5) times and the mechanical strength of the gel well by (1,32–1,80) times for agar and (1,49–1,57) times for pectin due to the stabilizing action of Magnetofood nanoparticles, which allows to reduce the amount of gelling agent by (9.0–11.0)% for agar and by (7.0–9.0)% for pectin.