Search Results (13)

This study investigates how molecular weight, ionic strength, and ionic composition influence the performance of sodium lignosulfonate as a dispersant for titanium dioxide (TiO₂) suspensions. Adsorption behavior was quantified using a quartz crystal microbalance with dissipation monitoring (QCM-D), while dispersion efficiency was assessed in concentrated suspensions via particle analysis (LUMiSizer) and in pastes through rheological measurements. In salt-free conditions, no adsorption occurs; however, the observed low particle size and viscosity can be attributed to depletion stabilization by non-adsorbing lignosulfonates. Both low- and high-molecular-weight fractions exhibit dispersing performance, but high-molecular-weight lignosulfonate provides the greatest stability across electrolyte variations. Increasing ionic strength enhances adsorption, leading to elastic particle network formation and higher viscosity due to reduced Debye length. With divalent ions, this effect is stronger and promoted by divalent cation bridging. These findings underscore the importance of tailoring lignosulfonate molecular weight and dosage to operating conditions, supporting formulation strategies for mineral-rich suspensions and industrial effluents. Future work should address long-term stability, temperature effects, and behavior on hydrophobic surfaces. Full article

This study aimed to investigate the interactions between soluble soybean polysaccharides (SSPS) and milk proteins, namely, casein and whey protein, and to evaluate their effects on the stability of acidified milk beverages under different degrees of thermal denaturation. Casein, whey protein, and SSPS were used as raw materials to prepare mixed solutions under varying pH conditions. A combination of analytical techniques, including centrifugal sedimentation rate, particle size distribution, ζ-potential measurement, differential scanning calorimetry (DSC), size-exclusion chromatography (SEC), and LUMisizer stability analysis, was employed to systematically examine the interactions between SSPS and the two proteins, as well as the influence of thermal treatment at 120–140 °C (casein) and 65–78 °C (whey protein). The results demonstrated that under acidic conditions (pH 3.5–4.5), SSPS formed compact complexes with casein, effectively stabilizing casein dispersions through steric hindrance and electrostatic repulsion. In contrast, SSPS exhibited a limited stabilizing ability toward whey protein due to its strong tendency to aggregate, which hindered the formation of uniform complexes. Regarding thermal denaturation, casein heated at 140 °C for more than 40 min showed pronounced κ-casein dissociation and aggregation, resulting in reduced stability of the SSPS–casein system. For whey protein, increasing thermal denaturation (complete denaturation at 78 °C for 30 min) led to the formation of larger aggregates, with particle size increasing from 198.23 nm to 213.33 nm and ζ-potential decreasing from −3.77 mV to −2.01 mV, thereby diminishing the stability of the SSPS–whey protein system. Overall, this study elucidates the interaction mechanisms of SSPS with casein and whey protein, and highlights the role of thermal denaturation, thereby providing theoretical guidance for the effective application of SSPS in acidified milk beverages. Full article

This study aimed to elucidate the effect of pH on the stability of soluble soybean polysaccharide (SSPS)-stabilized dairy beverages. A single-factor experimental design was employed using model systems containing 1.0% (w/v) protein and 0.4% (w/v) SSPS, with pH values adjusted from 3 to 7. System stability was comprehensively evaluated through centrifugation sedimentation rate, particle size distribution, ζ-potential, viscosity, and LUMisizer analysis. As pH increased from 3 to 7, the stability first decreased and then increased, showing the lowest stability at pH 5 and the highest stability at pH 6–7. At pH 5, large SSPS–protein aggregates formed due to the proximity to the isoelectric point (pI) of milk proteins, resulting in increased viscosity (6.83 mPa·s) and reduced ζ-potential (−5.8 mV). Conversely, at pH 6–7, strong electrostatic repulsion and steric stabilization led to small, uniformly dispersed particles and minimal transmittance change (<5%) in LUMisizer analysis. These findings clarify the stabilizing mechanism of SSPS and provide practical guidance for pH regulation in the formulation of dairy beverages. Full article

Soybean Soluble Polysaccharide (SSPS) is a natural anionic polysaccharide with protein content extracted from soybean residue. However, the impact of molecular weight and degree of esterification (DE) of soybean polysaccharides on protein stabilization remains a topic of debate. This study aimed to clarify the composition, macromolecular structure, and protein stabilization mechanism of SSPS and its various fractions with differing DEs and molecular weights (MWs). Nine polysaccharide fractions were isolated from three types of SSPSs with varying DEs and MWs using membrane ultrafiltration treatment. The analysis of monosaccharide composition and protein content reveals that the first component of soybean polysaccharides with high (847 kDa) molecular weight and low DE(SSPS20I) possesses the highest (7.25%) concentration of galacturonic acid (GalA) and a lower (0.83%) protein content compared to high-esterification SSPS. Meanwhile, the analysis of amino acids revealed that glutamic acid and aspartic acid were the primary amino acids across all protein components. It was also evident that alkaline treatment influenced the amino acid composition of SSPS. Atomic Force Microscopy (AFM) further substantiated that the components of SSPS exhibit distinct morphological and structural characteristics. The effects of SSPS fractions on the stability of Acidic Milk Drinks (AMDs) were investigated and evaluated using LUMi-Sizer. The results suggest that SSPS20I provided better stabilization in AMDs. This work establishes critical structure–property correlations, revealing that both DE and MW govern SSPS stabilization efficacy through synergistic effects of electrostatic repulsion, steric hindrance, and interfacial adsorption capacity. Full article

The stability of ceramic suspensions is a key factor in the preparation and shaping of ceramic bodies. The presented work offers an experimental determination of ceramics suspensions stability using the LUMiSizer analytical centrifuge, focusing on kinetic behaviour using transmission profiles and instability indexes. Multiple ceramic systems comprising corundum, metakaolin, and zirconia suspensions were experimentally examined under varying solid contents, dispersant dosages, and additive concentrations. Results showed that highly loaded corundum suspensions with dispersant (Dolapix CE64) achieved excellent stability, with an instability index below 0.05. Compared to classical sedimentation tests, which are time-consuming and not highly sensitive, LUMiSizer offers a suitable alternative by guaranteeing correct kinetic data and instability indexes indicating suspension behaviour using centrifugal force. Comparisons of the LUMiSizer results and data obtained using the modified Stokes law confirmed increased terminal velocities in experiments with metakaolin suspensions, indicating the sensitivity of the centrifuge to the effect of dispersion medium shape. The influence of porogen (waste coffee grounds) on the stability of corundum suspensions was also investigated, followed by slip casting to create and characterize a ceramic body, confirming the possibility of shaping based on stability results. Furthermore, instability indices are suggested as a rapid, quantitative method for comparing system stability and as an auxiliary criterion to the rheological measurements. Optimal dispersant concentration for zirconia-based photocurable suspensions was identified as 8.5 wt.%, which minimized viscosity and, at the same time, assured maximal kinetic stability. Integrating the LUMiSizer analytical centrifuge with standard methods, including sedimentation tests and rheological measurements, highlights its value as a powerful tool for characterizing and optimizing ceramic suspensions. Full article

Colloidal behavior of kaolinite particles in water was investigated in this manuscript, without and with the addition of a polymer flocculant (non-anionic polyacrylamide (PAM)), using diverse imaging techniques in addition to LUMisizer. The addition of PAM was found to be causing the formation of bridges among particles thus increasing their settling rates to the bottom of the container. To assess the size of flocs and the potential morphology of PAM around particles and their clusters, the state of flocs formation and polymer distribution was analyzed through various microscopical techniques, namely scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM results revealed that, in the absence of PAM, the floc structure of the sediment was loose and irregularly distributed, while the presence of PAM made the sediment structures greatly denser. Later, using LUMisizer, dynamic light scattering (DLS) and the zeta potential of kaolinite, sedimentation, and colloidal behavior of suspension came under scrutiny. Using LUMisizer, the maximum packing and settling rates of the particles were experimentally obtained as roughly 44 vol%; settling rates were estimated in 63–352 µm/s when centrifugal force varied and, using maximum packing values, compressive yield was estimated to vary between 48–94 kPa. The results of this study are instructive in choosing appropriate polymers and operating conditions to settle clay minerals in tailing ponds. Additionally, the maximum packing of kaolinite particles was simulated with spherical particles with varied polydispersity to connect DLS data to the maximum packing values obtained using LUMisizer; the little discrepancy between simulation and experimental values was found to be encouraging. Full article

Developing uniform ceramic-coated separators in high-energy Li secondary batteries has been a challenging task because aqueous ceramic coating slurries have poor dispersion stability and coating quality on the hydrophobic surfaces of polyolefin separators. In this study, we develop a simple but effective strategy for improving the dispersion stability of aqueous ceramic coating slurries by changing the mixing order of the ceramic slurry components. The aqueous ceramic coating slurry comprises ceramics (Al₂O₃), polymeric binders (sodium carboxymethyl cellulose, CMC), surfactants (disodium laureth sulfosuccinate, DLSS), and water. The interaction between the ceramic slurry components is studied by changing the mixing order of the ceramic slurry components and quantitatively evaluating the dispersion stability of the ceramic coating slurry using a Lumisizer. In the optimized mixing sequence, Al₂O₃ and DLSS premixed in aqueous Al₂O₃-DLSS micelles through strong surface interactions, and they repel each other due to steric repulsion. The addition of CMC in this state does not compromise the dispersion stability of aqueous ceramic coating slurries and enables uniform ceramic coating on polyethylene (PE) separators. The prepared Al₂O₃ ceramic-coated separators (Al₂O₃–CCSs) exhibit improved physical properties, such as high wettability electrolyte uptake and ionic conductivity, compared to the bare PE separators. Furthermore, Al₂O₃–CCSs exhibit improved electrochemical performance, such as rate capability and cycling performance. The half cells (LiMn₂O₄/Li metal) comprising Al₂O₃–CCSs retain 90.4% (88.4 mAh g⁻¹) of initial discharge capacity after 150 cycles, while 27.6% (26.4 mAh g⁻¹) for bare PE. Furthermore, the full cells (LiMn₂O₄/graphite) consisting of Al₂O₃–CCSs exhibit 69.8% (72.2 mAh g⁻¹) of the initial discharge capacity and 24.9% (25.0 mAh g⁻¹) for bare PE after 1150 cycles. Full article

The effects of molecular weight (MW) and degree of esterification (DE) of soluble soybean polysaccharide (SSPS) on the stability of casein under acidic conditions were investigated. The ability of SSPS to stabilize casein was characterized by the content of SSPS–casein complex, the LUMiSizer instability index, average particle size, zeta potential, and storage experiments. The long-term storage stability of the mixtures was related to their ability to combine casein and the stability of the complexes. At the same DE, SSPSs with medium MW formed more complexes with casein than SSPSs with high or low MW; and at the same MW, SSPSs with medium or low DE formed more complexes than SPSSs with high DE. In addition, SSPSs with higher MW had a better stabilizing behavior due to the large steric repulsion between complexes. SSPSs with high MW and low DE showed the best ability to stabilize casein under acid conditions. Full article

The influence of the amount of inulin addition (3%, 6%, 9%, 12% or 15% w/w) on the physicochemical properties of natural yogurt was analyzed. The acidity (titration; pH), texture parameters (penetration test), viscosity curves (rotational rheometer), microrheology (macroscopic viscosity index, MVI; elasticity index, EI; solid-liquid balance—SLB; multi-speckle diffusing-wave spectroscopy, MS-DWS) and physical stability (syneresis; LUMiSizer test) of yogurts were investigated. All samples were non-Newtonian pseudoplastic liquids. The sample with 15% inulin content presented an approx. 4% higher pH value (4.34), 3-fold greater MVI and almost 5-fold higher penetration force, compared to the control sample (0% of inulin). In turn, the use of inulin addition in the range of 3–15% w/w resulted in a reduction of syneresis (p < 0.05). A linear decrease in the values of instability indexes and sedimentation velocities was noted in the function of inulin content increase (LUMiSizer test). The application of inulin (in the range of 3–15% w/w) as a functional additive to yogurts significantly contributed to enhancement of their physical stability. Summing up, the possibility of obtaining natural yogurts with a high content of this prebiotic has been demonstrated, thus such products can be classified as functional foods and a health claim can be put on the label. Full article

Coconut oil-in-water emulsions were prepared using three polysaccharides: Dendrobium officinale polysaccharide (DOP), propylene glycol alginate (PGA), gum arabic (GA) and their polysaccharide complexes as emulsifiers. The effects of the ratio of the compounded polysaccharides on their apparent viscosity and interfacial activity were explored in this study. The average particle size, zeta potential, microstructure, rheological properties, and physical stability of the emulsions prepared with different compound-polysaccharides were studied. The results showed that mainly DOP contributed to the apparent viscosity of the compound-polysaccharide, while the interfacial activity and zeta potential were mainly influenced by PGA or GA. Emulsions prepared with compound-polysaccharides exhibited smaller average particle sizes, and microscopic observations showed smaller droplets and less droplet aggregation. In addition, the stability analysis of emulsions by a dispersion analyzer LUMiSizer showed that the emulsion prepared by compounding polysaccharides had better physical stability. Finally, all of the above experimental results showed that the emulsions prepared by PGA:DOP = 2:8 (total concentration = 1.5 wt%) and 2.0% GA + 1.5% DOP were the most stable. Full article

Polyelectrolyte nanocomposites rarely reach a stable state and aggregation often occurs. Here, we report the synthesis of nanocomposites for the oral delivery of insulin composed of alginate, dextran sulfate, poly-(ethylene glycol) 4000, poloxamer 188, chitosan, and bovine serum albumin. The nanocomposites were obtained by Ca²⁺-induced gelation of alginate followed by an electrostatic-interaction process among the polyelectrolytes. Chitosan seemed to be essential for the final size of the nanocomposites and there was an optimal content that led to the synthesis of nanocomposites of 400–600 nm hydrodynamic size. The enhanced stability of the synthesized nanocomposites was assessed with LUMiSizer after synthesis. Nanocomposite stability over time and under variations of ionic strength and pH were assessed with dynamic light scattering. The rounded shapes of nanocomposites were confirmed by scanning electron microscopy. After loading with insulin, analysis by HPLC revealed complete drug release under physiologically simulated conditions. Full article

The encapsulation of bicyclic monoterpene α-pinene into solid lipid nanoparticles (SLN) is reported using experimental factorial design, followed by high-end dispersion analyzer LUMiSizer^®. This equipment allows the characterization of the α-pinene-loaded SLN instability phenomena (e.g., sedimentation, flotation or coagulation), as well as the determination of the velocity distribution in the centrifugal field and the particle size distribution. In this work, SLN were produced by hot high-pressure homogenization technique. The influence of the independent variables, surfactant and lipid ratio on the physicochemical properties of SLN, such as mean particle size (Z-Ave), polydispersity index (PDI) and zeta potential (ZP), was estimated using a 2²-factorial design. The Z-Ave and PDI were analyzed by dynamic light scattering, while ZP measurements were recorded by electrophoretic light scattering. Based on the obtained results, the optimal SLN dispersion was composed of 1 wt.% of α-pinene, 4 wt.% of solid lipid (Imwitor^® 900 K) and 2.5 wt.% of surfactant (Poloxamer 188), depicting 136.7 nm of Z-Ave, 0.170 of PDI and 0 mV of ZP. Furthermore, LUMISizer^® has been successfully used in the stability analysis of α-pinene-loaded SLN. Full article

The increasing development of resistance of Candida species to traditional drugs represents a great challenge to the medical field for the treatment of skin infections. Essential oils were recently proposed to increase drug effectiveness. Herein, we developed and optimized (2³ full factorial design) Mediterranean essential oil (Rosmarinus officinalis, Lavandula x intermedia “Sumian”, Origanum vulgare subsp. hirtum) lipid nanoparticles for clotrimazole delivery, exploring the potential synergistic effects against Candida spp. Small sized nanoparticles (<100 nm) with a very broad size distribution (PDI < 0.15) and long-term stability were successfully prepared. Results of the in vitro biosafety on HaCaT (normal cell line) and A431 (tumoral cell line), allowed us to select Lavandula and Rosmarinus as anti-proliferative agents with the potential to be used as co-adjuvants in the treatment of non-tumoral proliferative dermal diseases. Results of calorimetric studies on biomembrane models, confirmed the potential antimicrobial activity of the selected oils due to their interaction with membrane permeabilization. Nanoparticles provided a prolonged in vitro release of clotrimazole. In vitro studies against Candida albicans, Candida krusei and Candida parapsilosis, showed an increase of the antifungal activity of clotrimazole-loaded nanoparticles prepared with Lavandula or Rosmarinus, thus confirming nanostructured lipid carriers (NLC) containing Mediterranean essential oils represent a promising strategy to improve drug effectiveness against topical candidiasis. Full article