Emulsion Stability Research Articles

Enhancement of mannosylerythritol lipid-A on physicochemical stability, antioxidant activity, and bioavailability of bovine lactoferrin emulsion under different pH conditions.

This study systematically explored the enhancement of mannosylerythritol lipid-A (MEL-A) on physicochemical stability, antioxidant activity, and bioavailability of bovine lactoferrin (BLF) emulsion under different pH conditions by spectroscopic techniques, molecular simulation, and simulated in vitro digestion model. The bovine lactoferrin-MEL-A (BLF-MEL-A) emulsions were prepared and characterized with the Fourier infrared, of which results showed that high concentration MEL-A (1.00 mg/mL) changed the secondary structure of pH-induced BLF and rendered an increase in β-sheet and random coil fractions. Based on the results of fluorescence spectrum and isothermal titration calorimetry, hydrogen bonding, van der Waals forces, and electrostatic force were the interaction forces of BLF and MEL-A, which were similar to the simulated data of molecular docking and molecular dynamics. BLF-MEL-A emulsion also exerted considerable antioxidant activities and had great potential for functional food development. In addition, MEL-A could improve the stability of BLF emulsion in simulated in vitro digestion test, which promoted the bioavailability of BLF. Therefore, this study will facilitate to explore the interaction between BLF and MEL-A and expand the application of MEL-A as a food additive in food industry.

Egg White-Based Gels with Candelilla Wax: A Study of Rheological, Mechanical, Calorimetric and Microstructural Properties

Bigels (BGs) are innovative composite systems that integrate oleogel and hydrogel structures, and are gaining increasing attention for their unique textural and functional properties in food applications. This study evaluated the rheological and mechanical properties of egg white-based bigels incorporating candelilla wax (CW) as an oleogelator. The results indicate that different egg white protein (EWP) (5–10%) concentrations and hydrogel-to-oleogel ratios (20:80 to 80:20) significantly influenced the structural and functional properties of the bigels. Compression testing revealed no significant differences in strength across the tested range; however, higher EWP concentrations enhanced the stability of the BGs. Furthermore, increased candelilla wax oleogel (CWO) content (60%) markedly improved emulsion stability, resulting in superior strength, as confirmed by dynamic light scattering. Rheological studies demonstrated shear-thinning behavior, particularly at higher hydrogel content related to the oleogel (W/O), which exhibited the highest yield stress. Microstructural investigations confirmed the presence of a continuous oleogel phase within the bigels (W/O) and revealed the formation of a complex structure. These findings suggest that a reduced hydrogel-to-oleogel ratio can be utilized across various food systems, opening new possibilities for creating customized food structures with desirable textural and functional attributes.

Insight into Sequential Extrusion and Cysteine Treatment for Improving Rheological Characteristics and In Vitro Digestibility of Whey Protein Isolate.

The effects of sequential cold extrusion and cysteine (Cys) treatment on the rheological characteristics and in vitro digestibility of whey protein isolate (WPI) were researched in this work. Cold extrusion and Cys treatment increased the apparent viscosity, shear stress, Péclet number, and viscoelasticity of WPI. Furthermore, the emulsifying activity index enhanced in the order of WPI, Cys-treated WPI (Cys-WPI), cold-extruded WPI (CWPI), and extrusion-Cys treated WPI (Cys-CWPI). The emulsion stability index of Cys-CWPI was increased by 29.69% higher than that of WPI. Besides, the α-glucosidase inhibitory rate and xanthine oxidase inhibitory activity in the digests of Cys-CWPI were markedly increased compared with digests of WPI. The synergism of cold extrusion and Cys provides an effective approach for the application of whey protein-based thickeners and emulsifiers; meanwhile, its digestive products may assist in the development of hypoglycemic and uric acid-lowering foods.

Surface Activity of Hydrophobized Modified Starch Hydrolysates in Mixed Systems

The manuscript presents research focusing on the adsorption and emulsion properties of starch hydrolysates modified through acetylation, oxidation, and cross-linking. The techniques used in this study included measurements of equilibrium surface tension (du Noüy ring) dynamic surface tension (drop shape analysis), and the preparation and evaluation of emulsion stability (TURBISCAN). The surface activity of the acetylated starch hydrolysates is affected by the degree of acetylation. The acetylated starch 0.02Ac-H exhibited higher surface activity than the more highly substituted derivative 0.1Ac-H. Furthermore, it was shown that the surface activity of the components increased as the acetylated oxidized starch underwent hydrolysis. The fractions collected after 180 min using a membrane with a low separation capability (8 kDa) revealed the highest capacity for reducing surface tension. In binary systems consisting of starch derivatives and surfactants, synergistic effects in reducing surface tension were particularly noticeable in systems containing ionic surfactants. The addition of a cationic surfactant to the modified starch hydrolysate solution (1:6 mol/mol) resulted in a significantly more efficient saturation of the air/water interface. This study demonstrated that emulsions stabilized with modified starch hydrolysates remained stable over time, even when these hydrolysates constituted up to 60% of the emulsifier mixture.

Surfactant-Nanoparticle Formulations for Enhanced Oil Recovery in Calcite-Rich Rocks.

Aqueous surfactant-nanoparticle mixtures have received great attention recently for promoting a more sustainable and efficient enhanced oil recovery (EOR) process. However, colloidal stability under reservoir conditions is considered a great challenge. In addition, the way synergy operates in EOR is not clearly understood. This study aims to formulate a cost-effective surfactant-nanoparticle mixture in a formation brine for efficient EOR in calcite-rich oil reservoirs. For this, bare silica nanoparticles were covalently grafted using an epoxysilane and blended with two commercial surfactants, namely a zwitterionic alkyl hydroxysultaine (AHS) and a binary zwitterionic-nonionic (ZN) surfactant, for both additional steric stabilization and EOR. The effects of additives alone or their mixtures were examined at solid-fluid and fluid-fluid interfaces to explore their impact on EOR. The surfactant-nanoparticle blend often showed a pH-responsive behavior at solid-fluid and fluid-fluid interfaces with particles serving as carriers or surface activity improvers for surfactant resulting in different extents of rock wettability alteration and emulsification. In oil recovery tests, optimum surfactant concentrations were found to significantly increase crude oil recovery of formation brine by 36 ± 1% original oil in place (OOIP) in secondary spontaneous imbibition which was further enhanced by 14 ± 0.5% OOIP upon adding a low particle concentration (0.01 wt %). The surfactant-nanoparticle formulation was also efficient in producing residual crude oil in tertiary mode (6% OOIP additional oil recovery after formation brine). The oil recovery results disclosed a high dependence on the emulsification ability of the blends with AHS-particle dispersions producing more stable emulsions and thus more crude oil compared to that of ZN.

Highly Persistent and Robust Emulsion Stabilized by Hierarchical Cellulose Microgel through Stereo-hindrance under Extreme Conditions.

Emulsion stabilization oil-in-water under harsh conditions (e.g., hypersaline, acid and alkali, and high temperature) is a great challenge for conventional emulsion stabilizers, including surfactants or particles. Herein, a persistent and robust emulsion under harsh conditions is achieved via a sustainable solution based on a hierarchical cellulose microgel (h-CMG). h-CMG in aqueous suspension establishes stable 3D networks by its nanotentacles and microbody, which can spatially hinder the approach and coalescence of droplets to each other and stabilize the emulsion. Unlike the emulsion stabilized by minimizing the interfacial energy and protecting the water/oil interface, the emulsion spatially stabilized by h-CMG exhibits extensive tolerance to extreme conditions and the feature of stable high internal phase emulsion (80%, v/v). The related droplet size and emulsion volume are almost unchanged in the pH range of 1 to 14, in NaCl aqueous solution of 2 mol/L, or even at 80 °C for 12 h. This genuine biobased emulsifier is highly favorable to the food, cosmetics, and pharmaceutical industries without the risk of nanotoxicity, and it also can provide a reliable emulsifier for the chemical and drilling industries involving harsh operation circumstances.

Effect of pH shifting and temperature on the functional properties of a commercial pea protein isolate

AbstractBackground and ObjectivesIn the present study, the effect of a pH‐shifting method in combination with heat was investigated for its effects on the resulting surface and functional properties of a commercial pea protein isolate. The pH shifting process was performed at both acidic (pH 2) and alkaline (pH 10) pH and then adjusted back to neutrality. The heat‐treated samples were further subjected to heating and later neutralized at pH 7.FindingsThe results of these treatments indicated that an alkaline pH shifting, as well as its combination with heat, resulted in a significant increase in the solubility of the proteins, whereas an acidic pH shifting, and in combination with heat, reduced the stability of the proteins in solution. Additionally, some functional properties were enhanced by pH shifting, such as foaming capacity or emulsion stability, while other properties showed no alteration or were negatively impacted, such as foaming stability. Furthermore, analysis of the bubble structure of foams using a dynamic foam analyzer revealed that bubble sizes for samples shifted at pH 2 in combination with heat presented the biggest increase in bubble growth over time, creating a less stable foam.ConclusionsThe application of pH shifting and the use of heat can aid in the improvement of pea protein functionality and allow tailoring of these proteins for specific applications.Significance and NoveltyThis study utilized a simple method to achieve modifications in the protein structures, providing insights into the application of pea proteins into food products as emulsifying and foaming agents.

Effect of transglutaminase cross-linking on the structure and emulsification performance of heated black bean protein isolate.

Transglutaminase (TGase) is a heat-resistant biocatalyst with strong catalytic activity, which functions effectively under moderate temperature and pH conditions, and is used widely in protein cross-linking and recombination. Transglutaminase cross-linking is a novel and specific modification method for black bean protein isolate (BBPI). This article investigates the effect of transglutaminase cross-linking on the structure and emulsification performance of heated BBPI. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that heated BBPI with TGase had a higher molecular weight than heated BBPI without TGase, and the protein bands widened with increasing enzyme activity, indicating that TGase cross-linking promoted protein molecule aggregation. A high molecular weight polymer can better stabilize the oil-water interface, preventing the emulsion from layering. Fourier transform infrared (FTIR) spectroscopy showed that the α-helix content decreased from 15.64% to 13.75%, and the β-sheet content increased from 48.13% to 54.08%. The decrease in α-helix content and increase in β-sheet content could make the structure more stable and improve the emulsifying properties of heated BBPI. When TGase was 20 U g-1, the protein emulsification activity index (EAI) reached its highest value of 1.87 m2 g-1, and the emulsification stability index (ESI) value was 0.27 min (P < 0.05); these figures were 0.19 m2 g-1, and 0.07 min higher, respectively, than in the sample without added TGase. In summary, transglutaminase cross-linking has a positive effect on the structure and emulsification performance of heated BBPI and can be used as an effective method for BBPI modification. © 2024 Society of Chemical Industry.

Development and stability evaluation of double emulsions enriched with Anthocyanins from Juçara

This study aimed to develop double emulsions enriched with anthocyanins extracted from juçara, a fruit rich in bioactive compounds with antioxidant properties. Anthocyanins are promising natural colorants but present instability to pH and temperature variations, limiting their application. Encapsulation in double emulsions (W/O/W) is an effective solution to increase the stability and retention of these compounds. The main objective was to develop and evaluate the stability of the double emulsions, aiming to protect the anthocyanins during processing. The methodology included the anthocyanins extraction from juçara and the formation of primary emulsions, followed by incorporation into external aqueous phases, testing different (W/O)/W proportions and concentrations of Arabic gum. The most stable double emulsion showed higher anthocyanin retention, with an encapsulation efficiency of 98.04%. The double emulsion system proved effective in protecting anthocyanins against different pHs, temperatures, and storage times, highlighting its potential for application as natural colorants in foods.

Development of gel-like, high encapsulation efficiency and antibacterial cinnamaldehyde-loaded Pickering emulsion stabilized by EGCG enhanced whey protein isolate-gum arabic ternary nanocomplex

Pickering emulsions (PEs) loaded with essential oils have proven to be a promising delivery system in food preservation, thus attracting increasing research attention. In this study, epigallocatechin gallate (EGCG) enhanced whey protein isolate(WPI)-gum Arabic(GA) ternary spherical nanocomplex (WGE) was fabricated by thermal and pH double-induced method and used to stabilize antibacterial, antioxidant and sustained release Pickering emulsions loaded with cinnamaldehyde. The WGE nanocomplex exhibited biphasic surface wettability (78.2±2.8°), 1.73 times that of WPI, as well as outstanding interfacial tension (5.60 mN/m), 44.6 % lower than that of WPI-GA, mainly due to the electrostatic interactions between WPI and GA and enhanced surface hydrophobicity causing by EGCG, indicating its superb ability to stabilize Pickering emulsions. Using WGE nanocomplex as the Pickering emulsion stabilizer, PEs template was constructed. Confocal laser scanning microscopy (CLSM) showed the formation of a dense oil-water interface layer and gel-like network structure, which demonstrated good storage stability against creaming and coalescence, benefiting to cinnamaldehyde encapsulation. Finally, cinnamaldehyde was encapsulated effectively using this PEs pattern with high encapsulation efficiency under different conditions. The cinnamaldehyde Pickering emulsions (CPEs) demonstrated superior antioxidant ability against DPPH (>85 %) and ABTS (>78 %), as well as effective antibacterial capability against E. coli (>99.9999 %) and S. aureus (>99.99 %) than pure cinnamaldehyde. Moreover, CPEs showed slow sustained-release ability, which could satisfyingly prolong the biological activity of cinnamaldehyde. Therefore, the WGE stabilized cinnamaldehyde Pickering emulsions fabricated in this work might provide a promising alternative for the delivery of antibacterial and controlled release essential oils in the food industry.

Pickering emulsions embedded in Bletilla striata polysaccharide based nanogel for enhancing skin-whitening effect of essential oils.

To improve the retention time and skin-whitening efficacy of Atractylodes macrocephale essential oil (AMO), a novel Pickering emulsion based nanogel loaded with AMO (AMO-PEG) was successfully developed. This formulation employed nano-pearl powder (NPP) as the particle stabilizer for the Pickering emulsion and Bletilla striata polysaccharide (BSP) as the gel matrix. The pH, rheological properties, hardness, and elasticity of AMO-PEG were affected by the ratio of AMO-Pickering emulsion (AMO-PE) to BSP gel matrix. The results showed that AMO-PEG exhibited solid-like behavior and was capable of forming nanogels when the ratio of AMO-PE to BSP was 1:1. AMO-PE and AMO-PEG are two different dosage forms in the preparation of AMO. The effects of varying dosage forms on AMO were evaluated by in vitro transdermal release, skin irritation test, and skin-whitening effect. AMO-PEG conforms to the zero-order kinetic equation (R2 = 0.9189). The skin retention rate of AMO-PEG was 1.37 times higher than that of AMO-PE, indicating that AMO-PEG could continuously and slowly exert the whitening effect of the drugs. Compared with AMO-PE, AMO-PEG significantly increased the inhibition of tyrosinase activity and melanogenesis in B16F10 cells. AMO-PEG can promote the inhibition of B16F10 cells and improve the whitening effect of AMO and BSP. In conclusion, the Pickering emulsion based nanogel appears to be a promising strategy for enhancing the skin-whitening efficacy of both AMO and BSP.

Simultaneous use of disulphide oil for chemical‐enhanced oil recovery by emulsion formation and stability with asphaltene deposition control

AbstractDisulphide oil (DSO) is a by‐product of oil and gas refining processes that is generated during the removal of mercaptans and the sweetening of light hydrocarbons. Asphalt deposition, especially asphaltene deposition during enhanced oil recovery methods, reduces oil recovery from the reservoir, so the use of a substance such as DSO, which has the ability to control and reduce asphaltene deposition, can be effective in increasing oil recovery from the reservoir. In this research, a micromodel with a fracture design and a matrix that represents fracture reservoirs was utilized. These tests were conducted in two groups. The first group of tests is related to adding DSO to crude oil and using 70 to 30 vol.% oil–water emulsion containing salt, surfactant, and nanoparticles. The second group involved adding DSO to both crude oil and emulsion. The first group aimed at stimulation and the second group aimed at chemical enhanced oil recovery (C‐EOR). The formation and stability of water‐in‐oil emulsion was done by analyzing the average droplet size. As a result, in the first group of tests with the presence of DSO in the oil, by measuring the average diameter before and after injection of AOS surfactant, it was observed that the average droplet size decreased from 6.89 to 4.01 μm, which indicates an increase in the emulsion stability. In the second group, where DSO was present in both oil and water emulsion in injected oil, it can be seen that the average diameter of the droplets in the surfactant decreased from 5.12 to 3.21 μm.

Improved Emulsifying Performance of Agarose Microgels by Cross-Interfacial Diffusion of Polyphenols.

Noninterface-active polysaccharides can acquire better emulsifying properties through microgelation, yet optimizing their emulsifying performance remains a significant challenge. This study introduces a novel approach to enhance the emulsifying performance of polysaccharide microgels by leveraging the cross-interfacial diffusion of polyphenols, which promotes the interfacial adsorption of microgels. Tannic acid (TA) was predispersed in oil phases and subsequently emulsified with agarose microgel (AM) suspensions, and the impacts of TA diffusion on the emulsifying performance of AMs was investigated. In addition, the transmittance profiles of oil-water biphasic systems were found to innovatively indicate the cross-interfacial diffusion of TA and the interfacial adsorption of AMs. The current results suggest that an appropriate level of TA incorporation can benefit the emulsifying performance of AMs, correlating with decreased droplet sizes and improved physical stability of the emulsion. However, excessive TA might trigger the clustering of AMs before they reach the interfacial layer, adversely affecting the emulsion stability. In conclusion, the cross-interfacial diffusion of polyphenols offers a promising strategy to overcome the stability challenges encountered in polysaccharide microgel-stabilized emulsions.

Rubisco at interfaces II: Structural reassembly enhances oil-water interface and emulsion stabilization

Rubisco is the most abundant protein on earth and has gained extensive attentions as a novel food ingredient, such as an emulsifier. Extraction methods can significantly affect its molecular structures and consequently influence its oil-water interface and emulsion stabilization properties. This work aims to elucidate the role of the Rubisco molecular structure in stabilizing the oil-water interface and the multiphase system of emulsions. Ultrafiltration (mild) and acid precipitation-alkaline redispersion (extensive) were used to extract Rubisco from spinach leaves. Protein molecular properties were characterized by size exclusion chromatography (SEC), circular dichroism (CD), and fluorescence spectrometry. Subsequently, the oil-water interfacial properties, including the adsorption and rheological behavior in both small and large dilatational and shear deformations, and the emulsion stabilization properties of Rubisco were investigated. We found that acid precipitation-alkaline redispersion produced a Rubisco extract (RA) with extensive structural reassembling, compared to the one produced by ultrafiltration (RU), for which nativity was mostly retained. RA had two-fold higher surface hydrophobicity than RU, and this caused RA to adsorb faster to the oil-water interface and developed a stiffer solid-like interface (Gi’ = 26 ± 3 mN/m) than RU (Gi’ = 15 ± 2 mN/m), which was also more resistant to density changes in large dilatational deformations. Consequently, RA displayed higher emulsifying activity and emulsion stability to coalescence during bulk shear and storage. Additionally, structural reassembly resulted in a higher value of the zeta potential of RA, which made the emulsion more stable against flocculation, compared to RU. Our study demonstrates that structural reassembly might be a useful strategy to improve the behavior of plant proteins in oil-water interface and emulsion stabilization, and may stimulate the development of new plant protein-stabilized emulsion-based products.

Fabrication of interfacial crystallized oleogel emulsion for quercetin delivery with enhanced environmental stability and bioaccessibility.

Quercetin is a flavonoid compound with numerous bioactivities. However, the low solubility, easy degradation and low bioaccessibility limit its application. In this study, a novel interfacial crystallized oleogel emulsion was fabricated, where beeswax was used as the oleogelator, for quercetin encapsulation with enhanced stability and bioaccessibility. The process of interfacial crystallization was investigated using interfacial rheology and polarized microscopy, with a positive correlation between crystal density and beeswax content in the oil phase. Emulsion stability was directly linked to beeswax concentration in the oil phase, with 100 mg g-1 showing enhanced stability under storage, UVB light exposure and ionic conditions. Beeswax addition significantly increased the quercetin loading capacity of the emulsion; particularly, at a 200 mg g-1 beeswax concentration, the loading capacity was improved by 285.55%, and the environmental stability was enhanced against UV light and Ca2+. Ultimately, in vitro simulated digestion experiment indicated improved bioaccessibility of quercetin. This strategy significantly enriched the formulation of oleogel emulsion and its potential applications in delivering bioactive ingredients with high environmental vulnerability. © 2024 Society of Chemical Industry.

Exploring the Nexus Between Emulsifier Characteristics and Salmonella Typhimurium Viability in Oil‐in‐Water Emulsions

ABSTRACTMolecular characteristics of emulsifiers such as their molecular weight (MW) and surface charge, not only affect the stability of the emulsion but also can have an impact on its capacity to either inhibit or promote microbial proliferation. These characteristics can affect the behavior of pathogens such as Salmonella Typhimurium in emulsion systems. The growth and thermal resistance of S. Typhimurium were monitored at different oil content levels (20%, 40%, and 60%) in emulsions stabilized by three whey protein‐based emulsifiers: whey protein isolate (WPI), whey protein hydrolysate (WPH), and a modified WPI with an alteration of charge (WPI+). Our study revealed that emulsifier itself with different MW and surface charge had no effect on bacterial growth and inactivation without oil inclusion (p &gt; 0.05). However, it was found that higher bacterial growth rate at 60% oil content emulsion stabilized with WPI+ (0.65 ± 0.03 log CFU/h) than WPI (0.19 ± 0.04 log CFU/h), which showed the charge of emulsifiers has different effects on microbial dynamics in oil‐in‐water emulsion. Interestingly, WPI+ in emulsions also seemed to convey protection against thermal inactivation of bacteria. These data describe a complex interrelationship between the physicochemical characteristics of the emulsifier and its interacting nature with bacterial cells. They throw even more light on the insight about the importance of a strategic approach toward emulsifier selection in food formulations. This is crucial for the food safety and stability of products.

A Spray-Dried Self-Stabilizing Nanocrystal Emulsion of Traditional Chinese Medicine: Preparation, Characterization and ex vivo Intestinal Absorption

AbstractSalvia miltiorrhizae (Danshen, the rhizome of Salvia miltiorrhiza Bge.) and Chuanxiong rhizome (Chuanxiong, the rhizome of Ligusticum chuanxiong Hort.) are two traditional Chinese medicines that have been widely used for the treatment of cardiovascular and cerebrovascular diseases. However, formulation development is difficult due to the complexity of the active ingredients, particularly the water-insoluble tanshinones and volatile oil of Chuanxiong rhizome, which cannot be absorbed via oral administration in conventional dosage forms. This study aimed to develop a self-stabilized nanocrystal emulsion co-loading the water-soluble, insoluble, and volatile active ingredients of Salvia miltiorrhizae and Chuanxiong rhizome to improve the bioavailability of the drugs. In this work, a high-pressure homogenization method was used to prepare a self-stabilizing nanocrystal emulsion. The emulsion was then spray-dried using hydroxypropyl-β-cyclodextrin. The dispersibility and storage stability of the spray-dried emulsion, the particle size and morphology of the emulsion droplets, and the drug content and phase distribution of the reconstituted emulsion were evaluated. An everted intestinal sac model was established, and high-performance liquid chromatography was used to determine the concentration of six active components (ferulic acid, salvianolic acid B, senkyunolide A, ligustilide, cryptotanshinone, and tanshinone IIA) and to assess the cumulative uptake amount of the drug and the apparent permeability coefficient. A mixture of the crude materials of tanshinones extract, total salvianolic acid, ferulic acid, and volatile oil of Ligusticum Chuanxiong was used as a control. The results showed that the spray-dried emulsion can be easily reconstituted into a uniform submicron emulsion with no significant changes in particle size, morphology, and microstructure of the emulsion droplets compared with the original emulsion before drying. The self-stabilizing nanocrystal emulsion significantly improved the intestinal absorption of water-insoluble components (tanshinone IIA, cryptotanshinone, and ferulic acid), and volatile oil components (senkyunolide A and ligustilide). Overall, the spray-dried self-stabilizing nanocrystal emulsion represents a potential oral formulation for Salvia miltiorrhiza and Chuanxiong rhizoma.

Structure and functionality of Pleurotus geesteranus protein isolate as a function of pH.

Edible mushroom proteins hold great potential for food applications, but those extracted using the alkaline extraction-acid precipitation method typically exhibit poor solubility in neutral water, with the structural changes during acid precipitation remaining unclear. In this study, Pleurotus geesteranus protein isolate (PGPI) with high water solubility was prepared with alkaline extraction, followed by dialysis and freeze-drying, and the effects of pH on the structural and functional properties of PGPI were systematically investigated. PGPI was enriched in essential and aromatic amino acids, and the molecular weight of bands in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile was mainly distributed below 45kDa. The zeta potential of PGPI changed from +16.84 to 17.58mV when the pH increased from 2 to 9, with a pI of 4.3. At pH 7, PGPI showed a size of 232.7nm. Away from pH 7, the particle size of PGPI increased. When the pH decreased from 7 to 2, PGPI exhibited a lower α-helix structure content and a higher β-sheet content and a gradual decrease in fluorescence intensity. In addition, as the pH approached 4, H0 and the content of SS group increased to a peak. These results indicated that lowering the pH induced the development of more ordered protein structure, which could be the primary reason for the poor water solubility of P. geesteranus protein obtained through alkaline extraction and acid precipitation. Additionally, these structural changes result in alterations to its functional properties, including water-holding capacity, oil-holding capacity, foaming capacity, foaming stability, emulsion activity index, and emulsion stability index.

Lycopene-Loaded Emulsions: Chitosan Versus Non-Ionic Surfactants as Stabilizers.

Lycopene is a natural carotenoid with well-known benefits due to its antioxidant properties, including an anti-inflammatory effect in colorectal cancer and anti-angiogenic effects along with a reduction in the risk of prostate cancer and coronary heart disease. Due to their poor water solubility, photosensitivity and heat sensitivity, their incorporation in cosmetic and food matrices should be through encapsulation systems. In the present work, lycopene-loaded emulsions were prepared using two different types of stabilizers: non-ionic surfactants, testing several ratios of Tween 80 and Span 80, and chitosan, using chitosans of different viscosities and molecular weights. Soybean oil was found to be a suitable candidate for O/W emulsion preparation. Lycopene encapsulation efficiency (EE) of 70-75% and loading capacities of 0.14 mg/g were registered in stable emulsions stabilized either by non-ionic surfactants or acidified chitosans. Therefore, chitosan is a good alternative as a sustainable stabilizer to partially replace traditional synthetic ingredients with a new biodegradable, renewable and biocompatible material which could contribute to reduce the environmental impact as well as the ingestion of synthetic toxic materials by humans, decreasing their risk of suffering from chronic and complex pathologies, among which several types of cancer stand out.

Coalescence Frequency in O/W Emulsions: Comparisons of Experiments with Models.

We have studied the coalescence of oil in water emulsions under the influence of gravity. The emulsions were made with alkane oils and surfactants with varying physical chemistry. We chose cationic alkyl trimethylammonium bromides of different chain lengths and nonionic surfactants of ethylene oxide and sugar head groups, including polymeric surfactants. We observed phase separation in two steps. Creaming of the oil drops is followed by their rapid coalescence, increasing the average drop size and resulting in complete surfactant surface coverage of the interfaces. Full phase separation occurs after much longer times Tc when the emulsion drops coalesce dramatically. We have used a model by Dinh et al. to relate Tc to the coalescence frequency and hence to the activation energy for the rupture of the films between two neighboring drops. Our results support the view that the coalescence of stable emulsions (stable at least for a few hours) is a thermally activated process and is controlled by the surface compression elastic modulus. This modulus was determined using surface tension measurements and calculations using the Gibbs adsorption equation. The observed differences between ionic and nonionic systems are attributed to a two-step film rupture process in the case of ionic surfactants, which is not found in nonionic systems.