Rheological characterization of O/W emulsions incorporated with neutral and charged polysaccharides

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.

Insight into the Stabilization Mechanism of Succinylation Modification on Black Bean Protein Gels: Molecular Conformation, Microstructure, and Gel Properties

The objective of this work was to investigate the effect of succinylation treatment on the physicochemical properties of black bean proteins (BBPI), and the relationship mechanism between BBPI structure and gel properties was further analyzed. The results demonstrated that the covalent formation of higher-molecular-weight complexes with BBPI could be achieved by succinic anhydride (SA). With the addition of SA at 10% (v/v), the acylation of proteins amounted to 92.53 ± 1.10%, at which point there was a minimized particle size of the system (300.90 ± 9.57 nm). Meanwhile, the protein structure was stretched with an irregular curl content of 34.30% and the greatest processable flexibility (0.381 ± 0.004). The dense three-dimensional mesh structure of the hydrogel as revealed by scanning electron microscopy was the fundamental prerequisite for the ability to resist external extrusion. The thermally induced hydrogels of acylated proteins with 10% (v/v) addition of SA showed excellent gel elastic behavior (1.44 ± 0.002 nm) and support capacity. Correlation analysis showed that the hydrogel strength and stability of hydrogels were closely related to the changes in protein conformation. This study provides theoretical guidance for the discovery of flexible proteins and their application in hydrogels.

Interfacial multilayer self-assembly of protein and polysaccharides: Ultrasonic regulation, stability and application in delivery lutein

In this study, the layer-by-layer adsorption behavior of sodium caseinate, pectin, and chitosan on the oil-water interface was illustrated using multi-frequency ultrasound. We investigated the impact of ultrasound on various factors, such as particle size, zeta potential, and interfacial protein/polysaccharide concentration. It was observed that ultrasound has significantly decreased droplet size and increased the surface area at the interface, hence promoting the adsorption of protein/polysaccharide. In the sonicated multilayer emulsion, the concentrations of interface proteins, pectin, and chitosan increased to 84.82 %, 90.49 %, and 83.31 %, respectively. The findings of the study indicated that the application of ultrasonic treatment had a significant impact on the emulsion's surface charge and the prevention of droplet aggregation. As a result, the stability of the emulsion system, including its resistance to salt, temperature, and storage conditions, has been significantly improved. Moreover, the emulsion showed an increase in the retention rate of lutein by 21.88 % after a high-temperature water bath and by 19.35 % after UV irradiation. Certainly, the multilayer emulsion treated with ultrasound demonstrated a superior and prolonged releasing behavior. These findings demonstrated the suitability of the ultrasound treatment for the preparation of emulsions to deliver bioactive compounds.

Effect of soluble dietary fiber on soy protein isolate emulsion gel properties, stability and delivery of vitamin D3

Emulsion gels with denser network microstructure and stronger mechanical properties have attracted increasing attentions for delivering lipophilic compounds. In this study, the effect of three distinct soluble dietary fiber (inulin (IN), resistant dextrin (RD) and stachyose (ST)) on the rheological, mechanical and microstructural properties of soy protein isolate (SPI) emulsion gel were firstly investigated. Compared with RD and IN, ST significantly accelerated water holding capacity and thermal stability, which exhibited more compact microstructure and more uniform emulsified oil droplets. Subsequently, the stability and bioavailability of vitamin D3 (VD3) in different delivery systems (medium chain triglycerides (MCT) embedding, SPI-ST emulsion embedding, SPI emulsion gel embedding and SPI-ST emulsion gel embedding) were continue evaluated. In vitro simulated digestion experiment demonstrated that the bioaccessibility of encapsulated VD3 in SPI-ST emulsion gel (69.95 %) was much higher than that of free embedding (48.99 %). In vivo pharmacokinetic experiment revealed that the bioavailability of VD3 was significantly enhanced in SPI-ST gel (p < 0.05), with the AUC0-24h value of 25-OH VD3 (the main circulating form of VD3) were 1.34-fold, 1.23-fold higher than that of free embedding, MCT embedding, respectively. These findings provide a possible approach for the development of high protein/fiber functional foods containing enhanced hydrophobic bioactives.

Fabrication of bilayer emulsion by ultrasonic emulsification: Effects of chitosan on the interfacial stability of emulsion

In this study, the stable system of bilayer emulsion was fabricated by ultrasonic emulsification. The effect of chitosan (CS) addition (0.05 %-0.4 %, w/v) at pH 5.0 on the stability of rice bran protein hydrolysate-ferulic acid (RBPH-FA) monolayer emulsion was investigated. It was found that the addition of CS (0.3 %) could form a stable bilayer emulsion. The droplet size was 3.38 μm and the absolute ζ-potential value was 31.52 mV. The bilayer emulsion had better storage stability, oxidation stability and environmental stabilities than the monolayer emulsion. The results of in vitro simulations revealed the bilayer emulsion was able to deliver the β-carotene to the small intestine digestive stage stably and the bioaccessibility was increased from 22.34 % to 61.36 % compared with the monolayer emulsion. The research confirmed that the bilayer emulsion prepared by ultrasonic emulsification can be used for the delivery of hydrophobic functional component β-carotene.

Synergistic studies of Cassia tora gum with xanthan and guar gum: Carboxymethyl synthesis of cassia gum-xanthan synergistic blend and characterization

The present study describes the study of synergistic behavior of the Cassia tora (CTG) gum with xanthan gum (XG) and comparison with CTG and guar gum (GG) at varying temperatures. A carboxymethyl derivative of CTG: XG blend, having synergistic activity was synthesized and the reaction conditions were optimized using Taguchi's L'9 statistical design. The effect of solvent medium on the degree of substitution (DS) and the gelling property was also studied. The results reveal that synergistic interaction was found in the CTG: XG mixture whereas CTG: GG blend did not show synergistic behavior. The CTG: XG blend shows a highly viscous solution having 8371.9 cps viscosity at ambient temperature and gel is obtained by heating the blending solution and thereafter lowering the temperature. In continuum, an optimized carboxymethyl derivative (DS 0.16) also exhibits gelling properties. The carboxymethyl derivative was characterized by ¹H NMR, FTIR spectroscopy and FESEM analysis. The synergistic action of gums may be utilized in food, cosmetics and pharmaceutical applications.

The effect of organic acids and storage temperature on lite salad dressing rheology and Zygosaccharomyces parabailii growth

Zygosaccharomyces parabailii (Z. parabailii) causes spoilage in salad dressings due to its tolerance to osmotic pressure. The objective of this study was to determine the effect of organic acids and storage temperatures (4, 10, and 25 °C) on Z. parabailii growth and salad dressing mechanical properties. Acetic, lactic, and gluconic acids were used alone and in combination to acidify salad dressing. Z. parabailii-challenged formulations containing acetic acid alone tended to have lower counts of Z. parabailii when compared to Z. parabailii-challenged formulations containing other acid combinations. Overall, storage temperature had the most impact on Z. parabailii growth over a 45-day storage. Acidulant type and combination impacted salad dressing mechanical properties. During the 45-day storage period, all formulations showed increased viscosity, a Herschel–Bulkley viscosity profile, and elastic-dominant viscoelastic behavior. The degree of change in rheological behaviors over time was dependent on the type of acid used in the formulation.

Development of Olive Oil and α-Tocopherol Containing Emulsions Stabilized by FucoPol: Rheological and Textural Analyses

Biobased raw materials like natural polysaccharides are increasingly sought by the cosmetic industry for their valuable properties. Such biodegradable and usually non-cytotoxic biopolymers are commonly used in skin-care products as rheological modifiers, bioemulsifiers and/or bioactive ingredients. FucoPol is a natural polysaccharide with reported biocompatibility, emulsion-forming and stabilizing capacity, shear-thinning behavior and bioactivity (e.g., antioxidant capacity, wound healing ability) that potentiate its utilization in skin-care products. In this study, olive oil and α-tocopherol containing emulsions were stabilized with FucoPol. Although the presence of α-tocopherol negatively impacted the emulsions’ stability, it increased their emulsification index (EI). Moreover, FucoPol outperformed the commercial emulsifier Sepigel^® 305, under the tested conditions, with higher EI and higher stability under storage for 30 days. The formulation of FucoPol-based emulsions with olive oil and α-tocopherol was studied by Response Surface Methodology (RSM) that allowed the definition of the ingredients’ content to attain high emulsification. The RSM model established that α-tocopherol concentration had no significant impact on the EI within the tested ranges, with optimal emulsification for FucoPol concentration in the range 0.7–1.2 wt.% and olive oil contents of 20–30 wt.%. Formulations with 25 wt.% olive oil and either 0.5 or 2.0 wt.% α-tocopherol were emulsified with 1.0 wt.% or 0.7 wt.% FucoPol, respectively, resulting in oil-in-water (O/W) emulsions. The emulsions had similar shear-thinning behavior, but the formulation with higher FucoPol content displayed higher apparent viscosity, higher consistency, as well as higher firmness, adhesiveness and cohesiveness, but lower spreadability. These findings show FucoPol’s high performance as an emulsifier for olive oil/α-tocopherol, which are supported by an effective impact on the physicochemical and structural characteristics of the emulsions. Hence, this natural polysaccharide is a potential alternative to other emulsifiers.

Physiochemical characteristics and rheological investigations of camellia oil body emulsions stabilized by gum tragacanth as a coating layer

In this work, gum tragacanth (GT) was coated on the camellia oil body (OB) emulsions using an electrostatic deposition technique, and effects were investigated over a wide range of pH values, ionic strengths, temperatures, and freeze-thaw cycles. Special attention has been paid to the rheological features as a function of hydrocolloid concentration, thixotropy (hysteresis loop and in-shear structure recovery), temperature, and frequency. The electrostatic GT-OB surface protein interactions, confirmed by ζ-potential and confocal laser scanning microscopy measurements, led to the reduction of flocculation effects and enhancement of steric stabilization due to the adsorption of polysaccharides to OB surfaces. The activation energy values (E_a) appeared in the range of 21.92 to 8.02 kJ/mol at pH 4 as GT concentration increased from 0 to 1 wt%. The OBs are soft droplets with the degree of structure recovery (DSR) ranged from 0.451 to 0.533; however, GT coating showed synergistic effect on the DSR.

Preparation, characterization, and application of polysaccharide-based emulsions incorporated with lavender essential oil for skin-friendly cellulosic support

This study aimed to develop polysaccharide-based emulsions incorporated with lavender essential oil and their application on cellulosic support for patches obtaining. The lavender essential oil has been added to emulsions as an active compound mainly due to its antimicrobial properties. In this study, emulsions were used to deliver active ingredients (lavender essential oil). The chemical composition of essential oil was analyzed using gas chromatography-mass spectrometry (GC/MS). A total of seven emulsions (RiACL) were evaluated by determining rheological parameters and microbiological analysis. One of the emulsions (R7ACL) was applied to cellulosic support to obtain non-irritating textiles with controlled release of the active compound and moisturizing effects. Obtained cellulosic support was analyzed in terms of active compound controlled release, toxicity and antimicrobial testing, and skin analysis in healthy volunteers. It was found that the cellulosic supports treated with O/W emulsions are non-irritating, have softness and moisturizing effects, and can be used safely in topical applications for patches obtaining.

Bio-sourced polymers in cosmetic emulsions: a hidden potential of the alginates as thickeners and gelling agents

OBJECTIVE

The present work aims to investigate the impact of the alginates on the texture properties of cosmetic emulsions. For this purpose, five systems were selected: a classical emulsion without polymer and four emulsions containing polymers, as texture modifiers, at the level of 1%. Two different grades of alginates were chosen: one rich in mannuronic acid and one rich in guluronic acid. The objective was also to evaluate the potential of in-situ gelation during formulation. The guluronic rich sample was gelled to evaluate the effect on the texture properties. Finally, alginates-based systems were compared to the xanthan gum as a bio-sourced polymer reference.

METHODS

The sensory profile of the systems was established through a combination of prediction models and sensory analysis. The emulsion residual films obtained with natural polymers, Alginates and Xanthan Gum used as thickeners, as well as with the gelled version, were similar. However, the structural differences between polymers intervene during the characterisation of the sensory properties "before" and "during" application. A multi-scale physicochemical analysis was used to explain these differences.

RESULTS

Due to a controlled formulation process, the use of the polymers did not affect the microstructure of the emulsion which remained similar to the control one. The main impact of the polymers was observed on the macroscopic level: both alginates showed their unique textural signature, different from the classical Xanthan Gum. Due to weak structural differences, mechanical and textural properties were very close between the mannuronic rich and guluronic rich samples, when not gelled, compared to other emulsions. However, the molar mass and the mannuronic/guluronic acids ratio were proved to be crucial for the stretching and consistency properties, showing that this structural difference may have an impact when products are handled in traction and compression.

CONCLUSION

Meanwhile, the viscoelastic properties and the dynamic viscosity were greatly increased for the emulsion containing the gelled version of the alginate when compared to the classical polymers. The emulsion was also more consistent as proved by the textural analysis, pointing at better stability and suspension potential of the gelled emulsion versus the classical one containing the usual natural thickening agents.

Rheology by Design: A Regulatory Tutorial for Analytical Method Validation

The increasing demand for product and process understanding as an active pursuit in the quality guideline Q8 and, more recently, on the draft guideline on quality and equivalence of topical products, has unveiled the tremendous potential of rheology methods as a tool for microstructure characterization of topical semisolid dosage forms. Accordingly, procedure standardization is a dire need. This work aimed at developing and validating a methodology tutorial for rheology analysis. A 1% hydrocortisone cream was used as model cream formulation. Through a risk assessment analysis, the impact of selected critical method variables (geometry, temperature and application mode) was estimated in a broad range of rheological critical analytical attributes-zero-shear viscosity, upper-shear thinning viscosity, lower-shear thinning viscosity, infinite-shear viscosity, rotational yield point, thixotropic relative area, linear viscoelastic region, oscillatory yield point, storage modulus, loss modulus, and loss tangent. The proposed validation of the approach included the rheometer qualification, followed by the validation of numerous operational critical parameters regarding a rheology profile acquisition. The thixotropic relative area, oscillatory yield point, flow point and viscosity related endpoints proved to be highly sensitive and discriminatory parameters. This rationale provided a standard framework for the development of a reliable and robust rheology profile acquisition.

Progressing Towards the Sustainable Development of Cream Formulations

This work aims at providing the assumptions to assist the sustainable development of cream formulations. Specifically, it envisions to rationalize and predict the effect of formulation and process variability on a 1% hydrocortisone cream quality profile, interplaying microstructure properties with product performance and stability. This tripartite analysis was supported by a Quality by Design approach, considering a three-factor, three-level Box-Behnken design. Critical material attributes and process parameters were identified from a failure mode, effects, and criticality analysis. The impact of glycerol monostearate amount, isopropyl myristate amount, and homogenization rate on relevant quality attributes was estimated crosswise. The significant variability in product droplet size, viscosity, thixotropic behavior, and viscoelastic properties demonstrated a noteworthy influence on hydrocortisone release profile (112 ± 2–196 ± 7 μg/cm²/√h) and permeation behavior (0.16 ± 0.03–0.97 ± 0.08 μg/cm²/h), and on the assay, instability index and creaming rate, with values ranging from 81.9 to 120.5%, 0.031 ± 0.012 to 0.28 ± 0.13 and from 0.009 ± 0.000 to 0.38 ± 0.07 μm/s, respectively. The release patterns were not straightforwardly correlated with the permeation behavior. Monitoring the microstructural parameters, through the balanced adjustment of formulation and process variables, is herein highlighted as the key enabler to predict cream performance and stability. Finally, based on quality targets and response constraints, optimal working conditions were successfully attained through the establishment of a design space.

Stabilizing the Oil-in-Water Emulsions Using the Mixtures of Dendrobium Officinale Polysaccharides and Gum Arabic or Propylene Glycol Alginate

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

The effects of Plantago major seed gum on steady and dynamic oscillatory shear rheology of sunflower oil-in-water emulsions

The effects of Plantago major seed (PMS) gum on the rheological properties of the sunflower oil-based emulsions (steady shear flow and dynamic oscillatory rheology) were investigated. The results of steady shear flow experiments showed that the shear stress-shear rate, apparent viscosity-shear rate, and shear stress-time data were well fitted with Herschel-Bulkley, Carreau, and Tiu-Bogar models, respectively, and showed the highest R² and the lower root mean square error within different models. The strain and frequency sweep data indicated that all emulsions showed weak gel-like behavior, which showed stable interactions and entanglements in the emulsion structure. CoX-Merz rule was applied to investigate the relationship between complex viscosity (η*) and apparent viscosity (η_a ). In all emulsions containing PMS gum, η* > η _a and they did not obey from this rule.

PRACTICAL APPLICATIONS

The rheological properties of emulsion are critical features in stabilization of emulsion based products. The PMS gum can potentially be used in producing and stabilization of emulsion based products and effects of this gum on in oil in water emulsion can be useful in development of plant originated hydrocolloids in foods.

Rheological and physical parameters correlations in formulations with pinhão derivatives stability study: building up an analytical route

This study focuses on the correlation investigation between rheological and physical parameters and how it can contribute to optimize the topical formulations development. A gel and an emulgel containing pinhão derivatives, and their respective controls, were analyzed along six months of storage. A flowchart of analyses was proposed to use in topical formulation development when a benchmark is the goal or when it is necessary to change some raw material. All formulations were stable over the storage time and the formulations containing pinhão starch and coat extract presented similar properties to those of the control formulations. Correlations between rheological and physical data, as moisture content and particle size, were determined using Pearson's correlation coefficient. A moderate positive correlation was verified between particle size distribution and flow index, and a strong positive correlation between particle size and flow index. It was also found that the higher the moisture content, the higher the consistency index, quality factor, and apparent viscosity. The correlation analyses applied in this study contributed to build up an analytical route for topical formulation development, saving time and costs.

Recent advances in engineered chitosan-based nanogels for biomedical applications

Recent progress in the preparation and biomedical applications of engineered chitosan-based nanogels has been comprehensively reviewed.