Encapsulation of propionic acid within the aqueous phase of water-in-oil emulsions: reduced thermal volatilization and enhanced gastrointestinal stability.

Propionic acid (PA) is a water-soluble substance that has been shown to be beneficial for improving colon-related diseases. However, its appliance as a nutraceutical ingredient is hampered by its volatility, irritating odor, and easy absorption in the stomach and small intestine. A chitosan solution containing propionic acid was dispersed in a palm oil/corn oil mixture with polyglycerol polyricinoleate (PGPR) to form PA-loaded water-in-oil (W/O) emulsions. The stability of the emulsions was improved by the inclusion of both chitosan and palm oil, where the chitosan reduced the emulsion particle size and palm oil increased the viscosity. The thermal volatility and storage stability of the encapsulated propionic acid were significantly improved due to the stability of emulsion structure and hydrogen bonding between chitosan and propionic acid. Around 56% of propionic acid remained within the aqueous phase after the simulated gastrointestinal digestion. Our results indicate that W/O emulsions might be candidates as colon-targeted delivery systems for propionic acid, which could be beneficial for maintaining colon health.

Capsaicin encapsulated in W/O/W double emulsions fabricated via ethanol-induced pectin gelling: Improvement of bioaccessibility and reduction of irritation.

Capsaicin is a water-insoluble bioactive component with several beneficial physiological functions. However, the widespread application of this hydrophobic phytochemical is limited by its low water-solubility, intense irritation, and poor bioaccessibility. These challenges can be overcome by entrapping capsaicin within the internal water phase of water-in-oil-in-water (W/O/W) double emulsions via using ethanol to induce pectin gelling. In this study, ethanol was used both to dissolve capsaicin and to promote pectin gelation, thereby forming capsaicin-loaded pectin hydrogels that were used as the internal water phase of the double emulsions. Pectin addition improved the physical stability of the emulsions and led to a high encapsulation efficiency of capsaicin (>70 % after 7d storage). After simulated oral and gastric digestion, capsaicin-loaded double emulsions maintained their compartmentalized structure, avoiding capsaicin leakage in the month and stomach. The double emulsions were digested in the small intestine, thereby releasing the capsaicin. Capsaicin bioaccessibility was significantly enhanced after encapsulation, which was attributed to mixed micelle formation by the digested lipid phase. Furthermore, encapsulation of capsaicin within the double emulsions reduced the irritation in the gastrointestinal tissues of mice. This kind of double emulsion may have great potential for the development of more palatable capsaicin-loaded functional food products.

Improving shikonin solubility and stability by encapsulation in natural surfactant-coated shikonin nanoparticles.

It is significant to develop a colloidal delivery system to improve the water solubility, stability, and bioavailability of shikonin, which is a hydrophobic plant polyphenol with a variety of physiological activities. In this study, three kinds of natural surfactants (saponin, sophorolipid, and rhamnolipid) were used to prepare shikonin nanoparticles by the pH-driven method. The physicochemical and structural properties of the shikonin nanoparticles were characterized, including particle size, zeta potential, and morphology. The encapsulation efficiencies of shikonin nanoparticles coated with saponin and sophorolipid were 97.6% and 97.3%, respectively, which were much higher than that of rhamnolipid-coated shikonin nanoparticles (19.0%). Shikonin nanoparticles coated with saponin and sophorolipid showed good resistance to heat and light and maintained long-term stability during storage. Moreover, shikonin nanoparticles coated with saponin and sophorolipid improved their in vitro-bioavailability. PRACTICAL APPLICATION: These article results are of great importance for improving the stability and bioavailability of shikonin in functional foods, dietary supplements, or pharmaceutical preparations. Moreover, this study provided theoretical and practical guides for further research of shikonin nanoparticles and may promote the development of natural colloidal delivery systems.

Encapsulation of bitter peptides in diphasic gel double emulsions: Bitterness masking, sustained release and digestion stability.

Bitter peptides (BP) have been reported to exhibit beneficial physiological activities, but their bitter taste and digestive sensitivity currently limits their application in foods. In this study, W1/O/W2 double emulsions were prepared with bitter peptides in the inner water phase. The effects of gelling the inner and/or outer water phases, as well as crystallizing the oil phase, were then investigated. Aqueous phase gelation reduced the particle size of the double emulsions, improved their physical stability, increased their encapsulation efficiency for the bitter peptides, and reduced the bitterness of the peptides. After simulated oral and gastric digestion, the bitter peptide-loaded W1/O droplets in the double emulsions retained their structure, thereby preventing release of the peptides in the mouth and stomach. Our results suggest that gelled double emulsions may have great potential to create more palatable functional foods containing bitter peptides.

Improving the gastrointestinal activity of probiotics through encapsulation within biphasic gel water-in-oil emulsions.

The development of probiotics encapsulation strategies has always been a hot topic due to the high sensitivity of probiotics to processing, storage and the gastrointestinal environment. In this study, water in oil (W/O) emulsions of single-phase or dual-phase gels were constructed through the water phase, oil phase alone or all gels. And the W/O emulsions were used to encapsulate Bifidobacterium lactis V9. The effects of water, oil and biphasic gels on the physicochemical properties of the emulsion and the probiotic activity were investigated. Water, oil and biphasic gels contribute to the stability of emulsions. Oil-phase gels make the emulsion form a solid-like texture, while water-phase gels have no significant effect on the liquidity of the emulsion. The microscopic image shows that the probiotics were completely encapsulated in the internal aqueous phase due to the excellent water affinity of probiotic powder. In addition, all W/O emulsions retain higher probiotic activity, which is attributed to good physical isolation during the gastric phase, while oil-phase and biphasic gel emulsions have high probiotic activity after intestinal digestion due to reduced lipid digestion by oil-phase gels. A liquid or solid-state encapsulated probiotic emulsion has been developed and can be used as a coating sauce, solid fat, etc., which can provide additional ideas for probiotic encapsulation systems and functional food development.

Hydrogels assembled from hybrid of whey protein amyloid fibrils and gliadin nanoparticles for curcumin loading: Microstructure, tunable viscoelasticity, and stability.

Food grade hydrogel has become an ideal delivery system for bioactive substances and attracted wide attention. Hybrids of whey protein isolate amyloid fibrils (WPF) and gliadin nanoparticles (GNP) were able to assemble into WPF-GNP hydrogel at a low protein concentration of 2 wt%, among which WPF and GNP were fabricated from the hydrolysis of whey protein isolate under 85°C water bath (pH 2.0) and antisolvent precipitation, respectively. Atomic force microscope (AFM) images indicated that the ordered nanofibrillar network of WPF was formed at pH 2.0 with a thickness of about 10 nm. Cryo-SEM suggested that WPF-GNP hydrogel could arrest GNP within the fibrous reticular structure of the partially deformed WPF, while the hybrids of native whey protein isolate (WPI) and GNP (WPI-GNP hybrids) only led to protein aggregates. WPF-GNP hydrogel formed at pH 4.0 (85°C, 3 h, WPF:GNP = 4:1) possessed the largest elastic modulus (G' = 419 Pa), which far exceeded the elastic modulus of the WPI-GNP hybrids (G' = 16.3 Pa). The presence of NaCl could enhance the strength of WPF-GNP hydrogel and the largest value was achieved at 100 mM NaCl (∼105 mPa) in the range of 0∼500 mM due to electrostatic screening. Moreover, WPF-GNP hydrogel showed a high encapsulation efficiency for curcumin, 89.76, 89.26, 89.02, 85.87, and 79.24% for pH 2.0, 3.0, 4.0, 5.0, and 6.0, respectively, which suggested that the formed hydrogel possess good potential as a delivery system. WPF-GNP hydrogel also exhibited a good protection effect on the photodegradation stability of the loaded curcumin with the retention of up to 75.18% after hydrogel was exposed to ultraviolet radiation for 7 days. These results suggested that the viscoelasticity of WPF-GNP hydrogel was tunable via pH-, ion-, or composition-adjustment and the hydrogel showed excellent protection on the thermal and photodegradation stability of curcumin.

Encapsulation of bitter peptides in water-in-oil high internal phase emulsions reduces their bitterness and improves gastrointestinal stability.

Many peptides exhibit beneficial physiological functions, but their application in foods is limited because of their undesirable taste and their tendency to degrade when exposed to gastrointestinal conditions. In this study, water-in-oil high internal phase emulsions (W/O HIPEs) were used to encapsulate bitter peptides. A combination of confocal fluorescence and electron microscopy was used to confirm the formation of W/O HIPEs. The presence of high concentrations of bitter peptides increased the apparent shear viscosity, shear modulus and sedimentation stability. They also improved the oxidative stability of the HIPEs. Electronic-tongue and sensory analysis showed that encapsulated peptides within the HIPEs substantially reduced their bitterness. Moreover, a simulated gastrointestinal study showed that W/O HIPEs protected peptides from being released in the stomach. Our results show that W/O HIPEs can be used to mask the bitterness and improve the gastrointestinal stability of peptides, which may increase their utilization as bioactive ingredients in foods.