Search Results (171)

Protein-polyphenol-based delivery vehicles are effective strategies for encapsulating bioactive compounds, thereby enhancing their solubility and bioaccessibility. In this study, dihydromyricetin/soy protein isolate (DHM/SPI) complexes were used as emulsifiers to prepare Pickering emulsions for DHM delivery. The results show that DHM and SPI form negatively charged complexes through hydrogen bonding, and the complex size decreases and stabilizes with increasing DHM addition. The size of the emulsion droplets was inversely related to the concentration of DHM addition (c), particle concentration (w), and ionic strength (i). Conversely, the increasing oil phase concentration (φ) was positively correlated with droplet size. The CLSM results confirmed the expected oil-in-water emulsion, while the rheological behavior of the Pickering emulsion highlighted its elastic, gel-like network structure and non-Newtonian fluid properties. Moreover, DHM effectively slowed lipid oxidation in the emulsion, and the bioaccessibility of DHM reached 33.51 ± 0.31% after in vitro simulated digestion. In conclusion, this emulsion system shows promising potential for delivering DHM and harnessing its bioactive effects. Full article

Natural polymer-based nanoparticles have emerged as promising stabilizers for Pickering emulsions, offering biocompatibility, environmental sustainability, and improved protection of active compounds. This study developed chitosan/gum arabic (CH/GA) nanoparticles as solid stabilizers for quercetin-loaded Pickering emulsions to enhance the stability and antioxidant bioactivity of quercetin (QE), a plant-derived flavonoid known for its potent radical-scavenging activity but limited by oxidative degradation. A systematic formulation strategy was employed to evaluate the effects of CH/GA concentration (0.5–2.0% w/v), oil type (olive, soybean, sunflower, and coconut), and oil volume fraction (ϕ = 0.5–0.7) on emulsion stability. The formulation containing 1.5% CH/GA and olive oil at ϕ = 0.6 exhibited optimal physical and interfacial stability. Quercetin (0.1% w/w) was incorporated into the optimized emulsions and characterized for long-term stability, particle size, droplet morphology, rheology, antioxidant activity (DPPH), cytocompatibility, and intracellular reactive oxygen species (ROS) protection using HaCaT keratinocytes. The olive oil-based formulation (D1-QE) exhibited greater viscosity retention and antioxidant stability than its soybean-based counterpart (E2-QE) under both room temperature (RT) and accelerated heating–cooling (H/C) storage conditions. Confocal microscopy confirmed the accumulation of CH/GA nanoparticles at the oil–water interface, forming a dense interfacial barrier and enhancing emulsion stability. HPLC analysis showed that D1-QE retained 92.8 ± 0.5% of QE at RT and 82.8 ± 1.5% under H/C conditions after 30 days. Antioxidant activity was largely preserved, with only 4.7 ± 1.7% and 14.9 ± 4.8% loss of DPPH radical scavenging activity at RT and H/C, respectively. Cytotoxicity testing in HaCaT keratinocytes confirmed that the emulsions were non-toxic at 1 mg/mL QE and effectively reduced H₂O₂-induced oxidative stress, decreasing intracellular ROS levels by 75.16%. These results highlight the potential of CH/GA-stabilized Pickering emulsions as a polymer-based delivery system for maintaining the stability and functional antioxidant activity of QE in bioactive formulations. Full article

Due to its gelling and thickening properties, sweet potato starch (Ipomoea batatas L.) could be a promising ingredient to improve characteristics such as the viscosity and consistency of foods like dressings. The objective of this study was to use sweet potato starch by adding it to salad dressing-type emulsion formulations. Sweet potato starch was characterized (microscopic appearance, granule size, and thermal properties). Four formulations (F1–F4) were developed incorporating different amounts of sweet potato starch (2 and 4%), and were characterized by particle size, emulsion stability, rheology, and sensory analysis. The starch granules were oval shaped, with a size range of 10–33 μm, and a temperature and enthalpy gelatinization (ΔH) of 69.08 °C and 10.72 J/g, respectively. The formulations were evaluated for 30 days, the particle size had a range of 2.18–13.88 μm, the emulsion stability was 98.89–100%, all formulations presented a creaming index at 0%, and the coalescence rate obtained values between −2.33 × 10⁻⁸ and 7 × 10⁻⁸Kc (s⁻¹) showing a significant difference. The consistency coefficient (K) was obtained, 2.477–35.207 Pa·sⁿ, and there was no significant difference between F1 and F2 with respect to a commercial dressing. In the sensory analysis, F2 presented greater acceptance. The values obtained suggest that sweet potato starch could be used in this type of food, showing similarities to the commercial brand. Full article

This work focuses on the stability analysis of water-in-oil macroemulsions with a crude oil from the Sacha Field in Ecuador. This field is an important hydrocarbon resource in Ecuador with a typical bottom freshwater drive. The comprehensive stability analysis includes coalescence, water resolution or phase separation, and water–oil interfacial tension and interfacial dilatational viscoelastic modulus measurements over time. Two main parameters, due to their relevance, were controlled in these experiments: water salinity and temperature. The analysis reported here is the first focused on this important resource in Ecuador. Findings shed light on which mechanisms more likely control the stability of these water-in-oil macroemulsions. Results herein suggest that regardless of temperature, low-salinity water favors emulsion stability, likely due to the tendency of a stiffer interface formation at low-ionic strength, as interfacial viscoelasticity measurements show. This implies that the low-ionic strength water from the aquifer can enable the formation of stable emulsions. In contrast, water resolution depends significantly on temperature, possibly due to higher sedimentation rates. The implication is that if emulsions do not break up before cooling off, the emulsion can become more stable. Finally, analysis of the interface buildup rates could explain the observed increase in emulsion stability over time. Full article

Periodontitis is a prevalent oral condition worldwide. Azithromycin, a conventional lipophilic drug for periodontal treatment, often causes systemic side effects when administered orally. To address this, azithromycin-loaded nano-emulgels were developed using olive oil as a carrier within a xanthan gum aqueous gel phase. This oil-in-aqueous gel emulsion was actuated into a foam for localized drug delivery in gingival and periodontal disease. The solubility of azithromycin in various vehicles was tested, with olive oil showing the best solubility (0.347 mg/mL). Thermodynamic stability testing identified viable nano-formulations, with encapsulation efficiencies ranging from 98 to 100%. These formulations exhibited rapid drug release within 2–8 h. Muco-adhesion studies and ex vivo permeability tests on porcine buccal mucosa highlighted the beneficial properties of xanthan gum for local drug retention within the oral cavity. Antimicrobial efficiency was assessed using minimum inhibitory concentrations against various oral pathogens, where the formulation with equal surfactant and co-surfactant ratios showed the most potent antibacterial activity, ranging from 0.390 to 1.56 µg/mL. This was supported by the shear-thinning, muco-adhesive, and drug-retentive properties of the xanthan gel base. The study also examined the influence of the oil phase with xanthan gum gel on foam texture, rheology, and stability, demonstrating a promising prototype for periodontitis treatment. Full article

Previous coreflooding results and wettability analyses in our group show that injection of naphthenic-acid-enriched water can improve oil recovery over traditional waterflooding. This observation is still a subject of research efforts without a definitive explanation. Naphthenic acids (NA) have been reported to drive wettability alteration and increase the water–oil interface elasticity. These alterations depend on the NA carbon number and aqueous-phase salinity, among other conditions, as reported in the literature. Smart-water flooding (SWF) research often links recovery to the initial wettability condition, being higher for initially oil-wet rock. SWF refers to a technique in which the aqueous-phase ion composition or/and salinity are changed to maximize oil recovery. Given NAs’ complex solution behavior, selecting acid combinations that prompt oil recovery is a difficult objective. The aim of this research is to determine the effects of select naphthenic acids on the oil–water interfacial rheology and wettability alteration and how these interfacial effects are associated with oil recovery under spontaneous imbibition. NAs were selected based on their carbon number, molecular structure, and solubility in the saline solution used in this research. We aimed at exploring which NAs should be used to regulate interfacial properties so as to either increase oil recovery or accelerate production. Time-domain nuclear magnetic resonance, interfacial dilatational rheology, and liquid-bridge experiments, i.e., proxy of snap-off, were conducted. A baseline was established using results obtained with a previously tested sulfate-rich aqueous phase, shown to be effective in recovering oil. Results show that NA14 and N18 increase the water–oil interfacial viscoelasticity and induce interfacial healing but led to different recovery factors. N10, while effective at inducing water wetness in oil-wet rock, is ineffective at increasing the recovery factor. We concluded that wettability and oil–water interfacial rheology are not exclusive, and instead they can synergistically favor EOR benefits. Moreover, oil recovery benefits under spontaneous imbibition are shown to depend strongly on the initial wettability conditions. Full article

In this study, we investigate the flow behavior of oil-in-water Pickering emulsions stabilized with bovine serum albumin (BSA). Through the use of a phase transition analogy and scaling parameters previously applied to surfactant-stabilized emulsions, we successfully describe the flow behavior, suggesting remarkable similarity in the rheology of these emulsion categories. Additionally, we explore the possibility of extending this modeling framework to the oscillatory mode. Above the jamming fraction, the scaled data in the oscillatory regime present a similar trend as the rotational rheology curves. However, upon closer examination of the scaling conditions, it becomes evident that the rescaling does not accurately describe the behavior of $\left|{\mathrm{G}}^{\mathrm{*}}\right|$. Despite this, our findings shed light on the universality of scaling parameters and provide valuable insights into the rheological behavior of these complex fluids. Full article

We developed highly stable shellac-based emulsions that incorporated alginate (Al) and κ-carrageenan (Kcar), two anionic polysaccharides capable of undergoing in situ crosslinking for various applications. The stability, droplet size distribution, and microstructure of these emulsions were assessed. Fluorescence microscopy confirmed nanoparticle accumulation at the oil–water interface, which enhanced stability. By leveraging the crosslinking potential of the polysaccharides, we created Pickering emulsion hydrogels (PEH) loaded with curcumin, a model food supplement with poor water solubility, and evaluated their release profiles in an in vitro gastrointestinal model. The results demonstrated two distinct release behaviors: full release in the small intestine and targeted release in the large intestine. Further study revealed fundamental differences in how Al and Kcar influence creaming, which led to a deeper investigation into the mechanisms behind these differences. Rheology measurements showed that a more complex mechanism governs the system’s viscosity. Small angle X-ray scattering (SAXS), Fourier transform infrared spectroscopy (FTIR), and further viscosity measurements revealed that hydrogen bonding in the Kcar emulsions formed unique structures, which provided superior resistance to creaming. This study highlights the potential of tailoring emulsion hydrogels for specific applications in food and drug delivery systems and offers new insights into the structural dynamics of biopolymer-stabilized emulsions. Full article

Yeast protein (YP) is rich in nutrients, but its emulsifying properties, especially emulsifying stability, still need to be improved. In this study, cationic polysaccharide chitosan (CS) and anionic polysaccharide xanthan gum (XG) were selected to enhance the emulsifying properties of protein emulsions. The preparation conditions of the emulsions were optimized by calculating particle size, zeta potential, emulsifying activity index, emulsifying stability index, and emulsifying capacity index, as well as macroscopic observation. The optimized emulsions were characterized using confocal laser scanning microscopy, rheology, Raman spectroscopy, color difference analysis, and storage stability. The results showed that the stability of yeast protein/modified yeast protein–chitosan (YP/EYP–CS) emulsions was better at pH 5.5, with a protein:polysaccharide ratio of 1:1 and an oil phase addition of 40%, while the stability of yeast protein/modified yeast protein–xanthan gum (YP/EYP–XG) emulsions was better at pH 3.5, with a protein:polysaccharide ratio of 1:1 and an oil phase addition of 50%. Further analysis indicated that the emulsions with CS had smaller particle sizes and lower initial viscosities, but more hydrogen bonds and better encapsulation of Monascus pigment (MP), especially the EYP–CS emulsion (81.18%). In contrast, the emulsions with XG had uniform droplet sizes and high thermal stability and exhibited obvious shear thinning behavior with increasing shear rates. The network structure of the emulsions was mainly elastic, and the hydrophobic interaction was stronger. This study provides insights into the utilization of yeast protein in the food industry and the development of emulsification systems. Full article

Emulsions play a crucial part in the whole beauty and care market, especially in skin and hair care domains where, due to their extraordinary versatility, they represent most of the finite products. Being thermodynamically unstable, one key aspect of their formulation is the use of stabilizers that ensure a long lifetime under different conditions. In this framework a key role is related to rheology modifiers, which include all those raw ingredients added to achieve, among others, desirable inflow characteristics that would not be possible to gain in their absence. In this review, strong attention was dedicated to different polymers and formulation strategies to understand the key role of these ingredients, widely used in emulsion-based cosmetics formulations. Full article

This study explored how combining supercritical fluid extraction (SFE) and enzymatic hydrolysis influences the structure and functionality of peptides recovered from filter-pressed shrimp waste. Freeze-dried press cake (PC) was defatted via SFE and hydrolyzed using Alcalase (ALC) and trypsin (TRYP). ALC-treated PC achieved the highest protein recovery (63.49%), extraction yield (24.73%), and hydrolysis degree (18.10%) (p < 0.05). SFE-treated hydrolysates showed higher zeta potential (−47.23 to −49.93 mV) than non-SFE samples (−25.15 to −38.62 mV) but had larger droplet sizes, indicating lower emulsion stability. SC-ALC displayed reduced fluorescence intensity and a red shift in maximum wavelength. TRYP hydrolysates reduced interfacial tension (20 mN/m), similar to sodium caseinate (Na-Cas, 13 mN/m), but with lesser effects. Dilatational rheology showed TRYP hydrolysates formed stronger, solid-like structures. These results emphasize protease efficacy over SFE for extracting functional compounds, enhancing shrimp waste valorization. Full article

Lidocaine is an analgesic agent frequently incorporated in topical formulations intended for application in minor surgical procedures or relieving neuropathic pain associated with numerous conditions, including post-herpetic neuralgia or diabetic peripheral neuropathy. In this study, Pickering o/w emulsions with halloysite nanotubes as a stabilizing agent and lidocaine incorporated in the internal phase were formulated with the use of the Quality by Design (QbD) approach. The selected emulsions were transformed into semisolid gels with poloxamer 407 as a thickening agent, and investigated for rheological and textural properties, indicating the mechanical features of the obtained gels. Moreover, the obtained formulations were tested for lidocaine release with the use of vertical Franz diffusion cells in order to assess the relationship between the applied composition and potential clinical applicability of the analyzed gels. The obtained results indicate that the emulsion droplet diameter is affected mostly by the oil and halloysite contents. The yield stress points, hardness and cohesiveness values of the obtained gels increased with the oil content. The drug release rate seems to be affected mostly by the concentration of the active ingredient in the oil phase. Full article

This work provides a comprehensive review of experimental methods used to measure rheological properties of interfacial layers stabilized by surfactants, asphaltenes, and proteins that are relevant to systems with large interfacial areas, such as emulsions and foams. Among the shear methods presented, the deep channel viscometer, bicone rheometer, and double-wall ring rheometers are the most utilized. On the other hand, the main dilational rheology techniques discussed are surface waves, capillary pressure, oscillating Langmuir trough, oscillating pendant drop, and oscillating spinning drop. Recent developments—including machine learning and artificial intelligence (AI) models, such as artificial neural networks (ANN) and convolutional neural networks (CNN)—to calculate interfacial tension from drop shape analysis in shorter times and with higher precision are critically analyzed. Additionally, configurations involving an Atomic Force Microscopy (AFM) cantilever contacting bubble, a microtensiometer platform, rectangular and radial Langmuir troughs, and high-frequency oscillation drop setups are presented. The significance of Gibbs–Marangoni effects and interfacial rheological parameters on the (de)stabilization of emulsions is also discussed. Finally, a critical review of the recent literature on the measurement of interfacial rheology is presented. Full article

Aligning with sustainable green practices, this study examines the partial replacement of chickpea protein isolate with commercially available autotrophic Chlorella vulgaris (Auto-Chlorella) and heterotrophic Parachlorella kessleri (Hetero-Chlorella) to assess impacts on food emulsions’ properties and potential functional value. Rheology and texture analysis show that Chlorella biocompounds enhance emulsions by creating a synergistic network with chickpea proteins. The type of Chlorella used significantly influences emulsion characteristics due to differences in culture and processing conditions. Hetero-Chlorella contributed to more structured emulsions, revealed by higher values of the viscoelastic functions (G′, G″, and G⁰_N), indicating a complex three-dimensional network (p < 0.05), while Auto-Chlorella excelled in augmenting dietary elements (p < 0.05), leading to emulsions rich in antioxidants and allowing for a ’rich in iron’ claim. Both types contribute to smaller oil droplet size, improved firmness, adhesiveness, and appealing coloration (p < 0.05). Preliminary findings on Vitamin B12 content suggest promising bioavailability potential. However, the nutritional density of Chlorella emphasizes the need for careful microbiological stability. Produced on a lab scale without preservatives, these emulsions highlight the need for preservation strategies in large-scale production. This research supports the potential for industrial microalgae-based mayonnaise, addressing consumer demand for innovation while prioritizing safety. Full article

Hydroxypropyl cellulose (HPC) is a non-digestible water-soluble polysaccharide used in various food, cosmetic, and pharmaceutical applications. In the current study, the aqueous solutions of six HPC grades, with molecular mass ranging from 40 to 870 kDa, were characterized with respect to their precipitation temperatures, interfacial tensions (IFTs), rheological properties and emulsifying and stabilization ability in palm (PO) and sunflower (SFO) oil emulsions. The main conclusions from the obtained results are as follows: (1) Emulsion drop size follows a master curve as a function of HPC concentration for all studied polymers, indicating that polymer molecular mass and solution viscosity have a secondary effect, while the primary effect is the fraction of surface-active molecules, estimated to be around 1–2% for all polymers. (2) Stable emulsions were obtained only with HPC polymers with M_w ≥ 400 kDa at concentrations approximately 3.5 times higher than the critical overlap concentration, c*. At PO concentrations beyond 40 wt. % or when the temperature was 25 °C, these emulsions appeared as highly viscous liquids or non-flowing gels. (3) HPC polymers with M_w < 90 kDa were unable to form stable emulsions, as the surface-active molecules cannot provide steric stabilization even at c ≳ 4–5 c*, resulting in drop creaming and coalescence during storage. Full article