Impact of sodium caseinate concentration and location on magnesium release from multiple W/O/W emulsions

Encapsulation of Monascus pigments in gel in oil in water (G/O/W) double emulsion system based on sodium caseinate and guar gum

In this study, a gel in oil in water (G/O/W) double emulsion system was developed with the objective of effectively encapsulating Monascus pigments and enhancing its stability. To this end, various formulations were prepared using guar gum co-dissolved with Monascus pigments in the internal phase and sodium caseinate as an outer phase surfactant. Different parameters were examined, including emulsion stability, encapsulation efficiency, rheological and tribological properties, as well as the light and thermal stability of the encapsulated Monascus pigments. The results demonstrated that Monascus pigments were effectively encapsulated in the G/O/W, with an encapsulation efficiency exceeding 90 %. The formulated system exhibited a relatively small particle size, which decreased with increasing guar gum and the external emulsifier contents. This resulted in an increase in viscosity accompanied by the formation of a gel-like structure and improved tribological properties, thereby enhancing the system's stability. The system with 1-1.25 % guar gum and 2.5 % sodium caseinate exhibited the highest stability for Monascus pigments, making them more resistant to heat and light. These findings have the potential to expand applications of Monascus pigments by providing a stable and effective encapsulation and delivery system that can also be utilized in the development of healthier food products.

Encapsulation Properties of Mentha piperita Leaf Extracts Prepared Using an Ultrasound-Assisted Double Emulsion Method

Double emulsions (W1/O/W2) have long been used in the food and pharmaceutical industries to encapsulate hydrophobic and hydrophilic drugs and bioactive compounds. This study investigated the effect of different types of emulsifiers (plant- vs. animal-based proteins) on the encapsulation properties of Mentha piperita leaf extract (MLE) prepared using the double emulsion method. Using response surface methodology, the effect of ultrasound-assisted extraction conditions (amplitude 20-50%; time 10-30 min; ethanol concentration 70-90%) on the total phenolic content (TPC) and antioxidant activity (percent inhibition) of the MLE was studied. MLE under optimized conditions (ethanol concentration 76%; amplitude 39%; time 30 min) had a TPC of 62.83 mg GA equivalents/g and an antioxidant activity of 23.49%. The optimized MLE was encapsulated using soy, pea, and whey protein isolates in two emulsifying conditions: 4065× g/min and 4065× g/30 s. The droplet size, optical images, rheology, and encapsulation efficiency (EE%) of the different encapsulated MLEs were compared. The W1/O/W2 produced at 4065× g/min exhibited a smaller droplet size and higher EE% and viscosity than that prepared at 4065× g/30 s. The higher EE% of soy and pea protein isolates indicated their potential as an effective alternative for bioactive compound encapsulation.

Grape seed proanthocyanidin-loaded gel-like W/O/W emulsion stabilized by genipin-crosslinked alkaline soluble polysaccharides-whey protein isolate conjugates: Fabrication, stability, and in vitro digestion

The present work aims to fabricate the genipin-crosslinked alkaline soluble polysaccharides-whey protein isolate conjugates (G-AWC) to stabilize W/O/W emulsions for encapsulation and delivery of grape seed proanthocyanidins (GSP). After crosslinking reaction, the molecular weight was increased and surface hydrophobicity was decreased. Then, the G-AWC and polyglycerol polyricinoleate (PGPR, a lipophilic emulsifier) were employed to prepare a GSP-loaded W/O/W emulsion with the addition of gelatin and sucrose in W₁ phase via a two-step procedure. Creamed emulsion could be fabricated at W₁/O volume fraction (Φ) of 10%-70% and further increased Φ to 75% or even up to 90% could obtain gel-like emulsion with notably elastic behaviors. In the W₁/O/W₂ emulsion with Φ of 80%, the encapsulation efficiency (EE) of GSP reached up to 95.86%, and decreased by ca. 10% after a week of storage. Moreover, the encapsulated GSP in the emulsion showed a remarkably higher bioaccessibility (40.72%) compared to free GSP (13.11%) in the simulated gastrointestinal digestion. These results indicated that G-AWC-stabilized W/O/W emulsions could be an effective carrier to encapsulate water-soluble bioactive compounds with enhanced stability and bioaccessibility.

Coencapsulation of (-)-Epigallocatechin-3-gallate and Quercetin in Particle-Stabilized W/O/W Emulsion Gels: Controlled Release and Bioaccessibility

Particle-stabilized W₁/O/W₂ emulsion gels were fabricated using a two-step procedure: ( i) a W₁/O emulsion was formed containing saccharose (for osmotic stress balance) and gelatin (as a gelling agent) in the aqueous phase and polyglycerol polyricinoleate (a lipophilic surfactant) in the oil phase; ( ii) this W₁/O emulsion was then homogenized with another water phase (W₂) containing wheat gliadin nanoparticles (hydrophilic emulsifier). The gliadin nanoparticles in the external aqueous phase aggregated at pH 5.5, which led to the formation of particle-stabilized W₁/O/W₂ emulsion gels with good stability to phase separation. These emulsion gels were then used to coencapsulate a hydrophilic bioactive (epigallocatechin-3-gallate, EGCG) in the internal aqueous phase (encapsulation efficiency = 65.5%) and a hydrophobic bioactive (quercetin) in the oil phase (encapsulation efficiency = 97.2%). The emulsion gels improved EGCG chemical stability and quercetin solubility under simulated gastrointestinal conditions, which led to a 2- and 4-fold increase in their effective bioaccessibility, respectively.

Different magnesium release profiles from W/O/W emulsions based on crystallized oils

Water-in-oil-in-water (W/O/W) double emulsions based on crystallized oils were prepared and the release kinetics of magnesium ions from the internal to the external aqueous phase was investigated at T=4°C, for different crystallized lipophilic matrices. All the emulsions were formulated using the same surface-active species, namely polyglycerol polyricinoleate (oil-soluble) and sodium caseinate (water-soluble). The external aqueous phase was a lactose or glucose solution at approximately the same osmotic pressure as that of the inner droplets, in order to avoid osmotic water transfer phenomena. We investigated two types of crystallized lipophilic systems: one based on blends of cocoa butter and miglyol oil, exploring a solid fat content from 0 to 90% and the other system based on milk fat fractions for which the solid fat content varies between 54 and 86%. For double emulsions based on cocoa butter/miglyol oil, the rate of magnesium release was gradually lowered by increasing the % of fat crystals i.e. cocoa butter, in agreement with a diffusion/permeation mechanism. However for double emulsions based on milk fat fractions, the rate of magnesium release was independent of the % of fat crystals and remains the one at t=0. This difference in diffusion patterns, although the solid content is of the same order, suggests a different distribution of fat crystals within the double globules: a continuous fat network acting as a physical barrier for the diffusion of magnesium for double emulsions based on cocoa butter/miglyol oil and double globule/water interfacial distribution for milk fat fractions based double emulsions, through the formation of a crystalline shell allowing an effective protection of the double globules against diffusion of magnesium to the external aqueous phase.

Effect of Abalone Hydrolysates Encapsulated by Double Emulsion on the Physicochemical and Sensorial Properties of Fresh Cheese

The intake of dietary salt through food now exceeds current nutritional recommendations and is thought to have negative effects on human health, such as the increasing prevalence of hypertension. This study was performed to investigate whether W₁/O/W₂ double emulsions can be used to enhance the saltiness of cheese without increasing the salt content (W₁ is distilled water or 1% abalone hydrolysate, and W₂ is 1% NaCl or 1% abalone hydrolysate + 1% NaCl solution). We also investigated the effect of adding abalone hydrolysate to the double emulsion as a saltiness enhancer. The cheeses were physico-chemically evaluated to determine curd yield, pH value, moisture content, color, texture, salt release rate, and sensory properties. No significant differences were observed in curd yield, pH value, moisture content, lightness, or redness between the cheeses made with and without the double emulsion. However, in the evaluation of salt release rate, fresh cheese made with double emulsion (W₁ = distilled water, W₂ = 1% NaCl + 1% abalone hydrolysate) was detected earlier than the control or the other treatments. In the sensory evaluation, fresh cheese made with the double emulsion showed higher scores for saltiness and overall preference than the control or the other treatments. We concluded that abalone hydrolysate encapsulated in a double emulsion (W₁ is water and W₂ is abalone hydrolysate and NaCl solution) could enhance the saltiness of fresh cheese while maintaining the same salt concentration, without altering its physical properties.

Effects of Several Natural Macromolecules on the Stability and Controlled Release Properties of Water-in-Oil-in-Water Emulsions

Water-in-oil-in-water (W/O/W) emulsions are effective vehicles for embedding application of active compounds but limited by their thermodynamic instability and rapid release properties. The present study added bovine serum albumin, whey protein isolate, whey protein hydrolysate, sodium caseinate, carboxymethylcellulose sodium, fish gelatin, apple pectin, gum arabic, ι-carrageenan, and hydroxypropyl chitosan separately to the internal or external aqueous phase to investigate their effects on the physical stabilities and controlled release properties of W/O/W emulsions. The effects of the natural macromolecules in the internal and external aqueous phases were different and depended upon the macromolecule structure and its mass fraction. The addition of the natural macromolecule strengthened the interfaces of emulsions, which improved the physical stability. The natural macromolecules that improved the stability often did not improve controlled release. Therefore, the balance between these properties needs to be considered when adding natural macromolecules to a W/O/W emulsion.

Influence of diffusive transport on the structural evolution of W/O/W emulsions

Double emulsions of the W/O/W type are compartmented materials suitable for encapsulation and sustained release of hydrophilic compounds. Initially, the inner aqueous droplets contain an encapsulated compound (EC), and the external phase comprises an osmotic regulator (OR). Over time, water and the solutes dissolved in it tend to be transferred from one aqueous compartment to the other across the oil phase. Water transfer being by far the fastest process, osmotic equilibration of two compartments is permanently ensured. Since the transport of the EC and OR generally occurs at dissimilar rates, the osmotic regulation process provokes a continuous flux of water that modifies the inner and outer volumes. We fabricated W/O/W emulsions stabilized by a couple of amphiphilic polymers, and we measured the inward and outward diffusion kinetics of the solutes. The phenomenology was explored by varying the chemical nature of the OR while keeping the same EC or vice versa. Microscope observations revealed different evolution scenarios, depending on the relative rates of transfer of the EC and OR. Structural evolution was mainly determined by the permeation ratio between the EC and the OR, irrespective of their chemical nature. In particular, a regime leading to droplet emptying was identified. In all cases, evolution was due to diffusion/permeation phenomena and coalescence was marginal. Results were discussed within the frame of a simple mean-field model taking into account the diffusive transfer of the solutes.

Influence of ionic complexation on release rate profiles from multiple water-in-oil-in-water (W/O/W) emulsions

Water-in-oil-in-water (W/O/W) double emulsions were prepared, and the kinetics of release of magnesium ions from the internal to the external water phase was followed. Different chelating agents (phosvitin and gluconate) were used to bind magnesium within the prospect of improving the ion retention in the internal aqueous droplets. Magnesium release was monitored for 1 month of storage, for each formulation, with and without chelation, at two storage temperatures (4 and 25 degrees C). Leakage occurred without film rupturing (coalescence) and was mainly due to entropically driven diffusion/permeation phenomena. The experimental results revealed a clear correlation between the effectiveness of chelating agents to delay the delivery and their binding capacity characterized by the equilibrium affinity constant. The kinetic data (percent released versus time curves) were interpreted within the framework of a kinetic model based on diffusion and taking into account magnesium chelation.