Opposite results of emulsion stability evaluated by the TSI and the phase separation proportion

Bifunctional performance of cellulose nanofibers grafted with polyhexamethylene guanidine in Pickering emulsion: Antibacterial activity and interfacial stability

This study developed the multifunctional cellulose nanofibers (CNFs) as emulsifier for preparation of antibacterial, ultrastable and non-toxic emulsion. To achieve these properties, CNFs were oxidated using sodium periodate to introduce aldehyde groups, which served as Schiff-base reaction sites for amino groups of polyhexamethylene guanidine (PHMG), yielding PHMG-grafted CNFs (PCNFs). The modified CNFs retained good emulsification ability while acquiring antibacterial properties. PCNFs were irreversibly absorbed onto the droplet surface, forming dense covering layers that prevented coalescence. Their strong entanglement and bridging flocculation capacities bonded adjacent droplets, creating stable droplet-fiber network structures. This enabled a creaming index of 90 % with only 4.0 % PCNFs. Emulsion stabilized by PCNFs achieved over 99 % antibacterial rate and 99 % cell viability, confirming their effective inactivation of bacteria and good biocompatibility. These findings showed the potential of PCNFs for developing antibacterial, ultrastable, and non-toxic emulsions for daily and biomedical applications.

Preparation of soluble starch/zinc oxide nanocomposites by solid-phase reaction and study of their antibacterial properties

Soluble starch/zinc oxide nanocomposites could be promising candidates for eco-friendly antimicrobial, food packaging, and a wide range of other utilization. In order to find a new way for the preparation of this kind of nanocomposites, an efficient and energy-saving reaction for the synthesis of soluble starch/zinc oxide nanocomposites has been investigated. The reaction was implemented in a solid state at room temperature without post-reaction calcination. In this process, the starting materials were ZnSO4·7H2O and KOH, while KCl served as the matrix and soluble starch was used as the surfactant. The prepared nanocomposites were characterized by Fourier infrared spectroscopy, X-ray diffraction spectrum, transmission electron microscope, scanning electron microscope, dynamic light scattering, and ultraviolet-visible absorbance spectroscopy. In addition, the UV-blocking effect and antimicrobial capability of the prepared nanocomposites were determined. The results showed that the nanocomposites were composed of soluble starch and ZnO nanoparticles. The mean diameter of ZnO nanoparticles was 12 nm. The results also showed that the suspension composed of nanocomposites were superior to that composed of simple zinc oxide nanoparticles in stability and inhibition of Escherichia coli and Staphylococcus aureus.

Structural modification of whey protein isolate via electrostatic complexation with Tremella polysaccharides and its effect on emulsion stability at pH 4.5

Emulsions play an important role in food systems by encapsulating and delivering active compounds, but maintaining their stability under various conditions can be challenging. This study explored how the concentrations of Tremella polysaccharides (TPs) (0-0.75 %) affects the structural of whey protein isolate (WPI) and the stability of their emulsions at pH 4.5. At this pH, electrostatic interactions between WPI and TPs exposed hydrophobic groups within the protein, increased β-sheet contents, and improved the hydrophilic-hydrophobic balance, which enhanced emulsifying performance. WPI-TPs complexes (WTS) showed a high emulsifying activity index (57.85 m2/g) and emulsion stability index (82.03 %). Compared to WPI-only emulsions, WTS emulsions had smaller particle sizes, lower Turbiscan Stability Index (TSI) values, and higher viscoelasticity, thermal stability, freeze-thaw stability, and re-emulsification capacity. Importantly, when the TPs concentration in WTS emulsions exceeded 0.375 %, the TSI value dropped below 1, showing no particle migration or peak thickness, indicating full emulsion stability. These findings suggest that TPs help stabilize WPI emulsions near their isoelectric point (pH 4.5) and offer a promising approach to improving WPI functionality in acidic environments. The WTS system provides a reliable way to stabilize emulsions under acidic conditions, supporting the development of natural, stable emulsifiers for food applications.

The use of heat-treated whey protein isolate as a natural emulsifier in fat-filled whey powder with a pre-emulsification process

BACKGROUND

Fat-filled whey powder is a type of whey powder that has been developed in recent years and is widely applied in the dry processing of infant formula milk powder. The addition of sodium caseinate, dextrin, or modified starch as emulsifiers can also improve the stability of fat-filled whey powders. However, regulations forbid the use of these substances as raw materials in powdered infant formulas. The development of new natural emulsifiers is therefore essential.

RESULTS

A pre-emulsification process (P-EP) with heat-treated whey protein (HWP) increased the solubility of fat-filled whey powders, reduced the Turbiscan stability index value, and reduced surface fat content. Microstructural analysis showed that the fat-filled whey powder in the experimental group (≤35 wt% fat in dry matter) exhibited a more uniform particle distribution in comparison with a control group.

CONCLUSION

The P-EP with HWP as a natural emulsifier can improve the stability and emulsifying effect in fat-filled whey powders. The use of P-EP with HWP was a promising method for producing fat-filled whey powder without artificial additives, relying solely on milk-derived ingredients for a clean label. © 2024 Society of Chemical Industry.

Free-radical-induced grafting of rice starch with gallic acid and evaluation of the reaction products' ability to stabilize Pickering emulsions

Pickering emulsions can be stabilized with native rice starch (NRS), but their hydrophobicity is low. Gallic acid (GA) has a simple molecular structure and a rich variety of functional groups. Pickering emulsions can be made more stable by hydrophobically modifying the esterification reaction of NRS with GA to improve its dual wetting properties. In this study, the free radical-induced grafting method was used to prepare rice starch-GA graft copolymer (NRS-g-GA). The addition of GA could improve the crystallinity and orderliness of NRS. The results of Fourier transform infrared spectroscopy and 1H NMR indicated that GA was successfully grafted onto NRS. After modification, the contact angle of NRS increased from 18.2° to 60.2° (NRS-g-GA; 1:1). The emulsion prepared from NRS-g-GA showed better stability than NRS, improving the emulsification of NRS. Its stable emulsion exhibited an emulsion system dominated by elasticity. Thus, GA could be grafted onto NRS to enhance its emulsifying properties, opening up new applications for GA and NRS and promoting the development of starch-based Pickering emulsions in the future.

A recyclable dispersant based on carbomer utilizing controllable viscosity for high-efficiency dispersion of carbon fibers

Good dispersion of carbon fibers is important for the carbon paper production, which is usually achieved using low carbon fiber concentrations and disposable dispersants. In this study, we developed carbomer as a recyclable and high-efficiency dispersant for carbon fibers. When the carbon fiber concentration was 0.1 wt%, carbon fiber suspension showed improved dispersion performance as increasing the carbomer dosage. It exhibited low Turbiscan Stability Index (TSI) of 0.41 and small change of delta backscattering between -0.5 to 0.8 % when using 0.5 wt% carbomer. However, the good dispersibility fade away when increasing the concentration of carbon fibers. Subsequently, the pH of the carbon fiber suspension was adjusted to 7.0 to improve the dispersibility by increasing the viscosity, but causing a worse flowability. Then the pH was further adjusted to 13.0 to ensure good flowability in the wet-forming process and good dispersibility at carbon fiber concentration of 0.5 wt%. More importantly, the dispersant was successfully recycled and still exhibited excellent dispersion effects for carbon fibers after 5 cycles. Notably, the high-efficiency dispersion of carbon fibers and the recyclability of dispersant were achieved simultaneously for the first time, which is suitable for the eco-friendly and sustainable production of carbon paper.

Co-encapsulation of curcumin and fucoxanthin in solid-in-oil-in-water multilayer emulsions: Characterization, stability and programmed sequential release

To enhance the bioavailability of bioactives with varying efficacy in the gastrointestinal tract (GIT), a co-delivery system of solid-in-oil-in-water (S/O/W) emulsion was designed for the co-encapsulation of two bioactives in this paper. S/O/W emulsions were fabricated utilizing fucoxanthin (FUC)-loaded nanoparticles (NPs) as the solid phase, coconut oil containing curcumin (Cur) as the oil phase, and carboxymethyl starch (CMS)/propylene glycol alginate (PGA) complex as the aqueous phase. The high entrapment efficiency of Cur (82.3-91.3%) and FUC (96.0-96.1%) was found in the CMS/PGA complex-stabilized S/O/W emulsions. Encapsulation of Cur and FUC within S/O/W emulsions enhanced their UV and thermal stabilities. In addition, S/O/W emulsions prepared with CMS/PGA complexes displayed good stability. More importantly, the formed S/O/W emulsion possessed programmed sequential release characteristics, delivering Cur and FUC to the small intestine and colon, respectively. These results contributed to designing co-delivery systems for the programmed sequential release of two hydrophobic nutrients in the GIT.

In Vitro Mucoadhesive Features of Gliadin Nanoparticles Containing Thiamine Hydrochloride

BACKGROUND

Gliadins have aroused significant interest in the last decade as suitable biomaterials for food and pharmaceutical applications. In particular, the oral route is the preferred method of administration for gliadin-based formulations, due to the affinity of this biomaterial for the gut mucosa. However, up to now, this has been demonstrated only by means of in vivo or ex vivo studies.

METHODS

This is why, in this study, various in vitro techniques were employed in order to evaluate the ability of polymeric nanoparticles, made up of a commercial grade of the protein and an etheric surfactant, to interact with porcine gastric mucin. The nanosystems were also used for the encapsulation of thiamine hydrochloride, used as a model of a micronutrient.

RESULTS

The resulting systems were characterized by a mean diameter of ~160-170 nm, a narrow size distribution when 0.2-0.6 mg/mL of thiamine was used, and an encapsulation efficiency between 30 and 45% of the drug initially employed. The incubation of the gliadin nanosystems with various concentrations of porcine gastric mucin evidenced the ability of the carriers to interact with the mucus glycoprotein, showing a decreased Zeta potential after a 4 h incubation (from ~-30 to -40 mV), while demonstrating that the encapsulation of the drug did not affect its bioadhesive features.

CONCLUSIONS

Altogether, these data support the conceivable application of gliadin nanoparticles as formulations for the oral administration of bioactive compounds.

Analyzing Emulsion Dynamics via Direct Visualization and Statistical Methodologies

Analytical centrifugation is a powerful technique that leverages the principles of centrifugal force and optical detection to characterize emulsion droplets in a label-free and high-throughput manner. Other advantages include minimal sample preparation effort and compatibility with a wide range of emulsion formulations. However, the resulting data can be rather complex and, thus, difficult to fully understand and interpret. To tackle this, we developed two analytical methodologies that enable an easy and intuitive understanding of the data as well as an objective, quantitative analysis and validated them using six model emulsions employing different surfactants. Through their application, insights with unprecedented clarity into dynamic emulsion behavior, stability mechanisms, and emulsion-based processes can be gained, facilitating advancements in fields such as food science, pharmaceuticals, and materials engineering.

Stability and 3D-printing performance of high-internal-phase emulsions based on ultrafine soybean meal particles

There are numerous studies on the application of soybean whey protein in three-dimensional (3D) printing. In this study, the effects of soybean meal particles (5%, 6%, 7%, 8%, 9%, and 10%) and oil-phase concentrations (70%, 72%, 74%, 76%, and 78%) on the stability and 3D-printing performance of a soybean-meal-based high-internal-phase emulsion were investigated. The results showed that the particle size of the emulsion decreased with increasing soybean meal particle concentration, and that increasing the concentration of the oil phase improved the viscoelasticity of the emulsion. Rheological tests further showed that the higher storage modulus of the emulsion indicated better support and stability. The emulsion with 8% soybean meal-particles and 76% oil-phase concentration exhibited the best printing effect. This study provides an effective solution for the preparation of stabilized high-internal-phase emulsions of soybean meal particles suitable for 3D printing.

Use of olive and sunflower protein hydrolysates for the physical and oxidative stabilization of fish oil-in-water emulsions

BACKGROUND

Olive and sunflower seeds are by-products generated in large amounts by the plant oil industry. The technological and biological properties of plant-based substrates, especially protein hydrolysates, have increased their use as functional ingredients for food matrices. The present study evaluates the physical and oxidative stabilities of 50 g kg-1 fish oil-in-water emulsions where protein hydrolysates from olive and sunflower seeds were incorporated at 20 g kg-1 protein as natural emulsifiers. The goal was to investigate the effect of protein source (i.e. olive and sunflower seeds), enzyme (i.e. subtilisin and trypsin) and degree of hydrolysis (5%, 8% and 11%) on the ability of the hydrolysate to stabilize the emulsion and retard lipid oxidation over a 7-day storage period.

RESULTS

The plant protein hydrolysates displayed different emulsifying and antioxidant capacities when incorporated into the fish oil-in-water emulsions. The hydrolysates with degrees of hydrolysis (DH) of 5%, especially those from sunflower seed meal, provided higher physical stability, regardless of the enzymatic treatment. For example, the average D [2, 3] values for the emulsions containing sunflower subtilisin hydrolysates at DH 5% only slightly increased from 1.21 ± 0.02 μm (day 0) to 2.01 ± 0.04 μm (day 7). Moreover, the emulsions stabilized with sunflower or olive seed hydrolysates at DH 5% were stable against lipid oxidation throughout the storage experiment, with no significant variation in the oxidation indices between days 0 and 4.

CONCLUSION

The results of the present study support the use of sunflower seed hydrolysates at DH 5% as natural emulsifiers for fish oil-in-water emulsions, providing both physical and chemical stability against lipid oxidation. © 2024 Society of Chemical Industry.

The Emulsification and Stabilization Mechanism of an Oil-in-Water Emulsion Constructed from Tremella Polysaccharide and Citrus Pectin

The objective of this study was to investigate the feasibility of the mixture of tremella polysaccharide (TP) and citrus pectin (CP) as an emulsifier by evaluating its emulsifying ability/stability. The results showed that the TP:CP ratio of 5:5 (w/w) could effectively act as an emulsifier. CP, owing its lower molecular weight and highly methyl esterification, facilitated the emulsification of oil droplets, thereby promoting the dispersion of droplets. Meanwhile, the presence of TP enhanced the viscosity of emulsion system and increased the electrostatic interactions and steric hindrance, therefore hindering the migration of emulsion droplets, reducing emulsion droplets coalesce, and enhancing emulsion stability. The emulsification and stabilization performances were influenced by the molecular weight, esterified carboxyl groups content, and electric charge of TP and CP, and the potential mechanism involved their impact on the buoyant force of droplet size, viscosity, and steric hindrance of emulsion system. The emulsions stabilized by TP-CP exhibited robust environmental tolerance, but demonstrated sensitivity to Ca2+. Conclusively, the study demonstrated the potential application of the mixture of TP and CP as a natural polysaccharide emulsifier.

Plant-Based Oil-in-Water Food Emulsions: Exploring the Influence of Different Formulations on Their Physicochemical Properties

The global focus on incorporating natural ingredients into the diet for health improvement encompasses ω-3 polyunsaturated fatty acids (PUFAs) derived from plant sources, such as flaxseed oil. ω-3 PUFAs are susceptible to oxidation, but oil-in-water (O/W) emulsions can serve to protect PUFAs from this phenomenon. This study aimed to create O/W emulsions using flaxseed oil and either soy lecithin or Quillaja saponins, thickened with modified starch, while assessing their physical properties (oil droplet size, ζ-potential, and rheology) and physical stability. Emulsions with different oil concentrations (25% and 30% w/w) and oil-to-surfactant ratio (5:1 and 10:1) were fabricated using high-pressure homogenization (800 bar, five cycles). Moreover, emulsions were thickened with modified starch and their rheological properties were measured. The physical stability of all emulsions was assessed over a 7-day storage period using the TSI (Turbiscan Stability Index). Saponin-stabilized emulsions exhibited smaller droplet diameters (0.11-0.19 µm) compared to lecithin (0.40-1.30 µm), and an increase in surfactant concentration led to a reduction in droplet diameter. Both surfactants generated droplets with a high negative charge (-63 to -72 mV), but lecithin-stabilized emulsions showed greater negative charge, resulting in more intense electrostatic repulsion. Saponin-stabilized emulsions showed higher apparent viscosity (3.9-11.6 mPa·s) when compared to lecithin-stabilized ones (1.19-4.36 mPa·s). The addition of starch significantly increased the apparent viscosity of saponin-stabilized emulsions, rising from 11.6 mPa s to 2117 mPa s. Emulsions stabilized by saponin exhibited higher stability than those stabilized by lecithin. This study confirms that plant-based ingredients, particularly saponins and lecithin, effectively produce stable O/W emulsions with flaxseed oil, offering opportunities for creating natural ingredient-based food emulsions.

Application of soybean isolate protein (SPI) and soy hull polysaccharide (SHP) complex in fermentation products

We investigated the stability of a soy protein isolate (SPI)/soy hull polysaccharide (SHP) composite and its effect on the quality of fermented products. Sonication contributed to a more stable SPI/SHP composite. Increasing SHP concentrations increased the viscoelasticity of the emulsions and decreased turbiscan stability index (TSI) values, indicating that SHP improved the emulsification and stability of the composite emulsions. The fermented products with SHP had an increased ability to bind to water. Hardness, gelling, chewiness, sourness, and astringency increased with polysaccharide addition. Additionally, SHP promoted acid production by lactic acid bacteria during storage. All groups had viscoelastic behavior (G' ˃ G″, tan δ < 1), with viscosity increasing and subsequently decreasing. TSI values were significantly lower in the treated groups than in the control group. The results revealed that SHP improved the sensory quality and storage stability of fermented products.

Assessing and Predicting Physical Stability of Emulsion-Based Topical Semisolid Products: A Review

The emulsion-based topical semisolid dosage forms present a high degree of complexity due to their microstructures which is apparent from their compositions comprising at least two immiscible liquid phases, often times of high viscosity. These complex microstructures are thermodynamically unstable, and the physical stability of such preparations is governed by formulation parameters such as phase volume ratio, type of emulsifiers and their concentration, HLB value of the emulsifier, as well as by process parameters such as homogenizer speed, time, temperature etc. Therefore, a detailed understanding of the microstructure in the DP and critical factors that influence the stability of emulsions is essential to ensure the quality and shelf-life of emulsion-based topical semisolid products. This review aims to provide an overview of the main strategies used to stabilize pharmaceutical emulsions contained in semisolid products and various characterization techniques and tools that have been utilized so far to evaluate their long-term stability. Accelerated physical stability assessment using dispersion analyzer tools such as an analytical centrifuge to predict the product shelf-life has been discussed. In addition, mathematical modeling for phase separation rate for non-Newtonian systems like semisolid emulsion products has also been discussed to guide formulation scientists to predict a priori stability of these products.

Acid emulsions stabilized by soy whey concentrates and soluble soybean polysaccharides: Role of biopolymer interaction strategies on stability against environmental stresses

This article focuses on the evaluation of different interaction strategies between soy whey concentrates (SWC) and soluble soybean polysaccharides (SSPS) at pH 3.0 on the emulsion stability against freeze-thawing and mechanical stirring. Emulsions were prepared from aqueous dispersions of both biopolymers (3.0% w/w SSPS and SWC, 1:1 mass ratio) and sunflower oil (10% w/w) by aqueous phase complexation (APC), interfacial complexation (IC) and interfacial complexation and sonication (ICS). SWC control emulsion was a poor emulsifying ability; SSPS addition, through the APC and ICS strategies, noticeably improved the SWC emulsifying properties. ICS emulsions showed the highest stability to environmental stresses, due a combination of low initial particle size, flocculation degree and steric hindrance promoted by the presence of SSPS chains at the interface. This study provides valuable information forthe utilization of whey soy proteins in acid dispersed systems stable to environmental stresses.

Composition, morphology, interfacial rheology and emulsifying ability of soy hull polysaccharides extracted with ammonium oxalate and sodium citrate as extractants

BACKGROUND

Soy hull, a by-product of crop processing, is rich in pectin-like polysaccharides that have potential for thickening, gelling and emulsifying applications. The effect of ammonium oxalate (SHPA) and sodium citrate (SHPS) on the conformation, physicochemical properties and emulsifying ability of soy hull polysaccharide (SHP) were investigated.

RESULTS

The composition analysis showed that SHPS had more polysaccharide, protein, and higher molecular weight than SHPA. Images of atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that SHPS molecules appeared spherical bodies with smooth and firm surfaces, while SHPA molecules appeared chain-like bodies with rough and wrinkled surface. At the oil-water interface, SHPS adsorbed faster and formed a more elastic interfacial layer than SHPA. The characterization of the prepared emulsions showed that the SHPS emulsion was a smaller particle size and more stable system within 30 days than SHPA emulsion, especially at the SHPS concentration of 9 mg mL^-1 . Images of cryo-scanning electron microscopy (cryo-SEM) also demonstrated SHPS formed clearer network structure on the surface of the oil droplets, compared to SHPA.

CONCLUSION

Overall, ammonium oxalate and sodium citrate significantly influenced the composition and properties of the SHP. SHPS exhibited a better emulsifying ability than SHPA, which was mainly due to the higher protein content of SHPS and the sodium ion (Na⁺ ) residue of sodium citrate. This study is useful for the extraction and application of SHP and other plant-based polysaccharides. © 2023 Society of Chemical Industry.

Strategical development of chrome-free tanning agent by integrating layered double hydroxide with starch derivatives

The development of sustainable and eco-friendly leather industry requires green tanning agents because of unbounded chromium (easily converted into hazardous Cr-VI) in chrome tanned leather. In this study, a chrome-free tanning agent (OS-LDHs) was established by integrating layered double hydroxide (magnesium aluminum zirconium hydrotalcite, LDHs) with starch derivatives. A series of oxidized starch (OS) were prepared as masking agents for LDHs tanning process. Among them, the weight-average molecular weight (Mw) of 1685 g/mol could be reached, which will promise the well-distribution of OS. The SEM and EDS analysis confirmed the uniform penetration of OS-LDHs, avoiding accumulation on the surface of crust leather. Notably, leather tanned by OS-LDHs achieved shrinkage temperature of 66.7 °C, porosity of 75.51 % and tear strength of 66.7 N/mm. Not only the hydrogen bond but also the coordination between NH₂, COOH in collagen and OS-2-LDHs improved the thermal stability of leather without destroying the collagen triple helix.

Exploring the influence of ultrasound on the antibacterial emulsification stability of lysozyme-oregano essential oil

A lysozyme-oregano essential oil (Lys-OEO) antibacterial emulsion was developed via ultrasonic treatment. Based on the general emulsion materials of ovalbumin (OVA) and inulin (IN), the addition of Lys and OEO successfully inhibited the growth of E. coli and S. aureus, two representatives of which were Gram-negative and Gram-positive bacteria respectively. The emulsion system in this study was designed to compensate for the limitation that Lys could only act on Gram-positive bacteria, and the stability of the emulsion was improved using ultrasonic treatment. The optimal amounts among OVA, Lys and OEO were found to be the mass ratio of 1:1 (Lys to OVA) and 20% (w/w) OEO. The ultrasonic treatment at the power of 200, 400, 600, and 800 W and time length of 10 min improved the stability of emulsion, in which the surface tension was below 6.04 mN/m and the Turbiscan stability index (TSI) did not exceed 10. The multiple light scattering showed that sonicated emulsions were less prone to delamination; salt stability and pH stability of emulsions were improved, CLSM image showed emulsion as oil-in-water type. In the meantime, the particles of the emulsions were found to become smaller and more uniform with ultrasonic treatment. The best dispersion and stability of the emulsion were both achieved at 600 W with a zeta potential of 7.7 mV, the smallest particle size and the most uniform particle distribution.

Study and optimization of oil-in-water emulsions formulated by low- and high-frequency ultrasounds

OBJECTIVE

A combined treatment using both low-frequency (20 kHz) and high-frequency ultrasounds (1.63 MHz) is a promising new process to stabilize emulsions with minimalist formulation. In order to optimize process parameters, a Doehlert experimental design was performed with oil-in-water emulsions, presently used for cosmetic products, composed of water, caprylic/capric triglycerides and oleic acid.

METHODS

Effects of treatment time, oil content and oleic acid content were studied on emulsion properties (droplet size, polydispersity index, ζ-potential and yield of oil incorporation) and on emulsion stability after a 28-day storage (creaming index, Turbiscan stability index (TSI) and oil release).

RESULTS

From experimental data, a model was established that allowed to study effects of each parameter and their interactions on emulsion formation and stability. Oleic acid content had a great impact on emulsion formation: It reduced droplet size, PDI and ζ-potential and increased yield of oil incorporation. However, a critical value could be highlighted, beyond which oleic acid effects reversed. Treatment time had an important beneficial effect on emulsion stability as it decreased creaming index, TSI and oil release after 28 days of storage. Oil content had a negative effect on emulsion formation and on emulsion stability. However, treatment time and oil content often had a beneficial synergistic effect.

CONCLUSION

The optimized conditions for emulsion processing were obtained through a desirability approach. They were experimentally validated.

Effect of emulsification methods on the physicochemical properties of emulsion stabilized by calcium carbonate and sodium alginate

Our lab’s studies have found that heavy calcium carbonate (CaCO₃) with sodium alginate (SA) can synergistically stabilize Pickering emulsion. However, there were significant differences in the flow characteristics of the emulsions obtained by different preparation methods during storage. Herein, in this current work, Pickering emulsions were prepared by two-step emulsifying method (SA was added into the primary emulsion stabilized by CaCO₃ for secondary shearing, M1) and one-step emulsifying method (oil phase was added to homogeneous dispersed CaCO₃-SA solution for one-step shearing, M2), respectively. The particle size, microstructure, rheology and microrheological properties of these two kinds of emulsions and the interaction of CaCO₃ with SA were analyzed. The results showed that the droplet size of M1 emulsion was 21.78–49.62 μm, and that of M2 emulsion was 6.50–11.87 μm. M1 emulsion had stronger viscoelasticity, and could transform into a gel state during storage. However, M2 emulsion remained in flow condition all the time which was related to the interaction between SA and CaCO₃ in the aqueous phase.

Lignin-based non-crosslinked nanocarriers: A promising delivery system of pesticide for development of sustainable agriculture

Lignin sulfonate (LS), a waste material from the paper pulping, was modified with benzoic anhydride to obtain benzoylated lignin sulfonates of adjustable hydrophilicity (BLS). When BLS was combined with difenoconazole (Di), a broad-spectrum fungicide, lignin-based, non-crosslinked nanoparticles were obtained either by solvent exchange or solvent evaporation. When a mass ratio of 1:5 LS: benzoic anhydride was used, the Di release from Di@BLS₅ after 1248 h was ca. 74 %, while a commercial difenoconazole microemulsion (Di ME) reached 100 % already after 96 h, proving the sustained release from the lignin nanocarriers. The formulation of Di in lignin-based nanocarriers also improved the UV stability and the foliar retention of Di compared to the commercial formulation of the fungicide. Bioactivity assay showed that Di@BLS₅ exhibited high activities and duration against strawberry anthracnose (Colletotrichum gloeosporioides). Overall, the construction of fungicide delivery nano-platform using BLS via a simple non-crosslinked approach is a novel and promising way to develop new formulations for nanopesticide and the development of sustainable agriculture.

Preparation of soybean dreg fiber solid emulsifier and its effect on the stability of Pickering emulsion

High purity insoluble dietary fiber (HPIDF) was extracted from Okara by compound enzyme method, and solid emulsifiers with different particle sizes were prepared by wet grinding. Its composition, structure and physicochemical properties were studied, and the influence mechanism of solid emulsifiers with different particle sizes on emulsifying properties and interface stability of Pickering emulsion was systematically studied. The results showed that the particle size of HPIDF decreased significantly, the ζ-potential, contact Angle and swelling capacity of HPIDF ncrease significantly (p < 0.05). HPIDF forms an adsorption layer at the oil-water interface, and some of them are connected to form a bridge network structure, which plays a role of steric hindrance. And the emulsion has excellent stability under different environmental factors. HPIDF are suitable raw materials as natural food-grade solid emulsifiers. It is cost-effective and eco-friendly to realize the high-value utilization of Okara resources, reduce resource waste, and extend the industrial chain.

Study on the Synergistic Effects between Petroleum Sulfonate and a Nonionic–Anionic Surfactant for Enhanced Oil Recovery

Nonionic–anionic surfactants are expected to be applied in chemical flooding due to their important properties such as ultralow IFT values, good salt tolerance, and no chromatographic separation in porous media. In this study, a new type of nonionic–anionic–hydrophobic group structure surfactant N,N-dihydroxyethylalkylamide carboxylate (EAMC) was synthesized. The synergistic effects between petroleum sulfonate (KPS) and EAMC in reducing interfacial tension (IFT) and emulsification properties were studied. The influences of salt, alkali and Ca2+ on the IFTs of surfactant solutions were also investigated. One-dimensional core flooding experiments were used to characterize the enhanced oil recovery capability of the KPS and EAMC mixed system. The experimental results show that both EAMC and KPS have high interfacial activity and can reduce IFTs to about 0.01 mN/m order of magnitude against decane at optimized concentrations. The area occupied by the hydrophilic group of EAMC on the interface is smaller than that of its own hydrophobic group. The interfacial film formed by EAMC alone is relatively loose. The IFTs of KPS containing different structure petroleum sulfonates is affected by the difference in the adsorption rate of petroleum sulfonates on the interface, which shows that both the dynamic and equilibrium interfacial tensions can have the lowest values. However, the IFTs of the EAMC solutions against crude oil can be reduced to ultralow values because the mixed tight adsorption film is formed by EAMC and crude oil fraction molecules with synergistic effect. On the other hand, the KPS molecule has a hydrophobic part with large size and no synergism with crude oil fractions can be observed in the solutions containing only KPS. The combination of EAMC and KPS shows synergistic effect, namely ultralow IFT values, good emulsification properties, high alkali tolerance, and good salt and Ca2+ tolerance during a wide percentage range of EAMC. The best formula of EAMC and KPS system can be applied for EOR after polymer flooding. The studies in this paper are helpful for the design and application of a chemical flooding formula with nonionic–anionic–hydrophobic group structure surfactants.

The Synthesis of Associative Copolymers with Both Amphoteric and Hydrophobic Groups and the Effect of the Degree of Association on the Instability of Emulsions

The acrylamide (AM)/methacryloyl ethyl sulfobetaine (SPE)/behenyl polyoxyethylene ether methacrylate (BEM) terpolymer (PASB) was synthesized by soap-free emulsion polymerization. Four types of PASBs were synthesized by adjusting the moles of AM and BEM with constant total moles of monomers. The synthesized copolymers were characterized by Fourier-transform infrared spectroscopy, thermogravimetry, molecular weight, and viscosity. By measuring the microscopic morphology and backscattered light intensity of the emulsions, the instability process of the emulsions prepared by PASBs was investigated in detail. The main instability processes of the emulsions prepared from PASBs within 45 min were flocculation and coalescence. The intermolecular association of copolymer PASBs was dominated by the behenyl functional groups on the molecular chains. The stability of the emulsions, which were prepared from isoviscosity aqueous solutions controlled by the concentration of the associative copolymers, was increased with the degree of association of copolymers. The hydrophobic association between the copolymer molecules can further slow down the flocculation and coalescence of the emulsion droplets on the basis of the same aqueous solution viscosity, which is one of the reasons for improving the stability of the emulsion.

Preparation and stability mechanisms of double emulsions stabilized by gelatinized native starch

Double emulsions are promising carrier systems for foods, pharmaceuticals, and cosmetics. However, their limited stability hinders their practical applications. We used gelatinized starch to develop stable double emulsions as carrier materials. The oil/water/water (O/W/W) double emulsions were formed by 5 wt% native corn starch, while oil/water/oil (O/W/O) double emulsions were formed by 7 wt% native corn starch and high-amylose starch with 60 % and 75 % amylose contents investigated by optical microscopy. Furthermore, the storage stability of double emulsions was revealed by droplet size distribution, microstructure, backscattering, rheological profiles, and low-field nuclear magnetic resonance (LF-NMR) imaging. Results confirmed that the O/W/O double emulsions stabilized by 7 wt% native corn starch had a smaller mean droplet size (11.400 ± 0.424 μm) and excellent storage stability (14 days) than O/W/W and O/W/O double emulsions prepared with high-amylose starch. Such unique double emulsions prepared with gelatinized native corn starch are good candidates of carrier materials.

Microstructures of encapsulates and their relations with encapsulation efficiency and controlled release of bioactive constituents: A review

Vitamins, peptides, essential oils, and probiotics are examples of health beneficial constituents, which are nevertheless heat-sensitive and possess poor chemical stability. Various encapsulation methods have been applied to protect these constituents against thermal and chemical degradations. Encapsulates prepared by different methods and/or at different conditions exhibit different microstructures, which in turn differently influence the encapsulation efficiency as well as retention of encapsulated core materials. This review provides a summary of various microstructures resulted from the use of selected encapsulation methods or systems, namely, spray coating; co-extrusion; emulsion-, micelle-, and liposome-based; coacervation; and ionic gelation encapsulation, at different conditions. Subsequent effects of the different microstructures on encapsulation efficiency and retention of encapsulated core materials are mentioned and discussed. Encapsulates having compact microstructures resulted from the use of low-surface tension and low-viscosity encapsulants, high-stability encapsulation systems, lower loads of core materials to total solids of encapsulants and appropriate solidification conditions have proved to exhibit higher encapsulation efficiencies and better retention of encapsulated core materials. Encapsulates with hollow, dent, shrunken microstructures or thinner walls resulted from inappropriate solidification conditions and higher loads of core materials, on the other hand, possess lower encapsulation efficiencies and protection capabilities. Encapsulates having crack, blow-hole or porous microstructures resulted from the use of high-viscosity encapsulants and inappropriate solidification conditions exhibit the lowest encapsulation efficiencies and poorest protection capabilities. Compact microstructures and structures formed between ionic biopolymers could be used to regulate the release of encapsulated cores.

Quantitative insight into dispersity and antibactericidal capability of silver nanoparticles noncovalently conjugated by polysaccharide-protein complexes

Precise prediction and measurement of dispersibility of silver nanoparticles (AgNPs) under atmospheric conditions are extremely vital for their potential commercial application. In the present work, the dispersibility of AgNPs capped by polysaccharide-protein from viscera of abalone (PSP-AgNPs) was studied using the combination of ultraviolet-visible spectroscopy (UV-vis), dynamic light scattering (DLS) and multiple-light-scattering (MLS) techniques. The results showed that the combination of UV/vis, DLS and MLS not only accurately determined the dispersibility of PSP-AgNPs, but also provided detailed information about the aggregation behavior of PSP-AgNPs. Furthermore, the results revealed a high dispersibility of PSP-AgNPs in the studied environment. The system temperature, pH value and thermal treatment (pasteurization and sterilization) had no effect on the dispersion of PSP-AgNPs in the effective concentration range against the pathogenic bacteria. Besides, an excellent stable dispersion and antibacterial activity against common pathogenic vibrio was also found in the dispersed PSP-AgNPs in seawater. Overall, the study provides a suitable method for the precise measurement of the dispersibility of AgNPs in environment. The AgNPs act as a potential bactericide with good dispersion and antibacterial activity in mariculture and other fields.