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Effects of Homogenization Models and Emulsifiers on the Physicochemical Properties of β-Carotene Nanoemulsions

Microfluidization and high pressure valve homogenization were applied to prepare β-carotene nanoemulsions, and the mathematical relationship between homogenization pressures and emulsion temperatures, homogenization pressures/cycles, and droplet sizes, were established. Emulsions through Microfluidizer had lower temperature and much smaller droplet sizes, compared with those through high pressure valve homogenizer. Four emulsifiers were compared for their capacities to stabilize nanoemulsions. The two large molecule emulsifiers, octenyl succinate starch (OSA) and whey protein isolate (WPI), were less effective for the formation of nanoemulsions with smaller droplets than the two small molecule emulsifiers, polyoxyethylene sorbitan monolaurate (Tween 20, TW) and decaglycerol monolaurate (DML). The nanoemulsion containing WPI was the most stable, while the one containing DML was the least stable. During storage, significant degradation of β-carotene occurred in all nanoemulsions, especially in the DML stabilized one, while WPI showed the greatest capacity to protect β-carotene from degradation.

Preparation, characterization and stability of curcumin-loaded zein-shellac composite colloidal particles

Curcumin-loaded zein-shellac composite particles were prepared by the antisolvent co-precipitation method. The encapsulation efficiency of curcumin was significantly improved from 82.7% in zein particles to 93.2% in zein-shellac complex particles. The result of differential scanning calorimetry suggested that curcumin in the polymeric matrix was in an amorphous state. Fourier transform infrared spectroscopy analysis revealed that curcumin had non-covalently interacted with zein and shellac, mainly through hydrogen bonding and hydrophobic interaction. Aggregates in irregular shapes, with large sizes, were found by atomic force microscopy, and conglutination, integration or fusion of different entities into network structures occurred at a high level of shellac. At the mass ratio of zein to shellac of 1:1, curcumin in the complex particles exhibited improved photochemical and thermal stability. Curcumin-loaded zein-shellac complex particles allowed the controlled release of curcumin in both PBS medium and simulated gastrointestinal fluids.

Structural characterization, formation mechanism and stability of curcumin in zein-lecithin composite nanoparticles fabricated by antisolvent co-precipitation

Curcumin (Cur) exhibits a range of bioactive properties, but its application is restrained due to its poor water solubility and sensitivity to environmental stresses. In this study, zein-lecithin composite nanoparticles were fabricated by antisolvent co-precipitation technique for delivery of Cur. The result showed that the encapsulation efficiency of Cur was significantly enhanced from 42.03% in zein nanoparticles to 99.83% in zein-lecithin composite nanoparticles. The Cur entrapped in the nanoparticles was in an amorphous state confirmed by differential scanning calorimetry and X-ray diffraction. Fourier transform infrared analysis revealed that hydrogen bonding, electrostatic interaction and hydrophobic attraction were the main interactions among zein, lecithin, and Cur. Compared with single zein and lecithin nanoparticles, zein-lecithin composite nanoparticles significantly improved the stability of Cur against thermal treatment, UV irradiation and high ionic strength. Therefore, zein-lecithin composite nanoparticles could be a potential delivery system for water-insoluble bioactive compounds with enhanced encapsulation efficiency and chemical stability.

Emulsion design for the delivery of β-carotene in complex food systems

ABSTRACT β-Carotene has been widely investigated both in the industry and academia, due to its unique bioactive attributes as an antioxidant and pro-vitamin A. Many attempts were made to design delivery systems for β-carotene to improve its dispersant state and chemical stability, and finally to enhance the functionality. Different types of oil-in-water emulsions were proved to be effective delivery systems for lipophilic bioactive ingredients, and intensive studies were performed on β-carotene emulsions in the last decade. Emulsions are thermodynamically unstable, and emulsions with intact structures are preferable in delivering β-carotene during processing and storage. β-Carotene in emulsions with smaller particle size has poor stability, and protein-type emulsifiers and additional antioxidants are effective in protecting β-carotene from degradation. Recent development in the design of protein-polyphenol conjugates has provided a novel approach to improve the stability of β-carotene emulsions. When β-carotene is consumed, its bioaccessibility is highly influenced by the digestion of lipids, and β-carotene in smaller oil droplets containing long-chain fatty acids has a higher bioaccessibility. In order to better deliver β-carotene in complex food products, some novel emulsions with tailor-made structures have been developed, e.g., multilayer emulsions, solid lipid particles, Pickering emulsions. This review summarizes the updated understanding of emulsion-based delivery systems for β-carotene, and how emulsions can be better designed to fulfill the benefits of β-carotene in functional foods.

Evaluation of non-covalent ternary aggregates of lactoferrin, high methylated pectin, EGCG in stabilizing β-carotene emulsions

The present study explored the potential of ternary aggregates composed of lactoferrin (LF), high methylated pectin (HMP) and EGCG in stabilizing β-carotene emulsions. Different ternary aggregates were fabricated by mixing the three components in different sequences, followed by spray drying. Fluorescence measurement and FTIR analysis indicated that ternary aggregates and LF-HMP binary complex were formed mainly through hydrogen bonding and hydrophobic interactions. The mixing sequences of three components and the spray drying process resulted in different structures of ternary aggregates. When applied to stabilizing β-carotene emulsions, ternary aggregates were effective in retarding droplet aggregation and creaming, and protecting β-carotene from degradation, compared to the binary complexes of LF, HMP or EGCG. The least loss of β-carotene was observed in the emulsions stabilized by spray-dried ternary aggregates. The conclusion obtained from the present study would be useful in the development of novel delivery systems for bioactive compounds.

Stabilization and Rheology of Concentrated Emulsions Using the Natural Emulsifiers Quillaja Saponins and Rhamnolipids

Concentrated emulsions are widely used in the cosmetic, personal-care, and food industries to reduce storage and transportation costs and to provide desirable characteristics. The current study aimed to produce concentrated emulsions (50 wt % oil) using two natural emulsifiers, quillaja saponins and rhamnolipids. The impacts of emulsifier concentrations on the particle sizes, rheological properties, and stabilities of concentrated emulsions were evaluated. Emulsion particle sizes were negatively correlated with the concentrations of both quillaja saponins and rhamnolipids, and rhamnolipids were more effective in producing smaller droplets. Both emulsifiers formed stable concentrated emulsions against a series of environmental stresses, including various temperatures (30-90 °C), salt concentrations (≤200 mM NaCl), and pHs (pH 5-8). The rheology tests suggested that concentrated emulsions stabilized by quillaja saponins or rhamnolipids presented shear-thinning behaviors and had relatively low consistency coefficients.

Formation and characterization of zein-propylene glycol alginate-surfactant ternary complexes: Effect of surfactant type

In this study, zein, propylene glycol alginate (PGA) and surfactant ternary complexes were fabricated by antisolvent co-precipitation method. Two types of surfactants (rhamnolipid and lecithin) were applied to generate zein-PGA-rhamnolipid (Z-P-R) and zein-PGA-lecithin (Z-P-L) ternary complexes, respectively. Results showed that the surfactant types significantly affected the properties of ternary complexes. The formation of ternary complexes was mainly due to the non-covalent interactions such as hydrogen bonding, electrostatic interaction and hydrophobic interactions among zein, PGA and surfactants. Moreover, the thermal stability of ternary complexes was enhanced with increasing the levels of both surfactants. Notably, ternary complex dispersions exhibited better stability against pH from 2 to 8. Furthermore, a compact network structure was observed in Z-P-R ternary complex, while Z-P-L ternary complex remained the spherical structure. These findings would provide new insights into the development of novel delivery system and expand the options, when zein-based complexes were utilized under different environment conditions.

Ethanol-induced composite hydrogel based on propylene glycol alginate and zein: Formation, characterization and application

A novel ethanol-induced composite hydrogel was prepared by two edible biopolymers: propylene glycol alginate (PGA) and zein. The effect of pH and different mass ratios of PGA and zein on the properties of the composite hydrogel was investigated. PGA and zein could form a gel induced by ethanol at pH ≥ 3.5, the stability, springiness, hardness and water holding capacity were decreased from pH 3.5 to 5.0. The hydrogen-bonding association was enhanced at pH 3.5 and porous structure was observed. The strength and springiness of the composite hydrogel decreased with increasing concentration of zein until the PGA/zein mass ratio was 5:1. At PGA/zein mass ratio of 5:1, the composite hydrogel exhibited a more elastic and tougher structure than other mass ratios at pH 3.5. Meanwhile, compared with the PGA hydrogel, the PGA-zein composite hydrogel showed great ability to sustain the release of curcumin in simulated gastrointestinal tract conditions.

Zein-hyaluronic acid binary complex as a delivery vehicle of quercetagetin: Fabrication, structural characterization, physicochemical stability and in vitro release property

The antisolvent coprecipitation method was utilized for fabricating the zein and hyaluronic acid complex at different mass ratios (100:5, 100:10, 100:15, 100:20, 100:25 and 100:30). Results showed that negatively charged zein-hyaluronic acid complex with small size (181.5 nm) was formed through the driving force of electrostatic attraction, followed by hydrogen bonding and hydrophobic effects. The incorporation of hyaluronic acid led to conformational change of zein, and improved its physical and thermal stability. Native hyaluronic acid showed a three-dimensional network structure, while zein-hyaluronic acid binary complex exhibited two different microstructures, including nanoparticles (zein: hyaluronic acid, above 100:20) and particle-filled-microgel (zein: hyaluronic acid, below 100:20). In addition, zein-hyaluronic acid complex was designed as a new delivery vehicle to anti- thermal degradation and control release of quercetagetin. These findings indicated that zein-hyaluronic acid complex would be a useful and promising delivery vehicle for embedding and protecting bioactive compounds.

Formation of soy protein isolate-carrageenan complex coacervates for improved viability of Bifidobacterium longum during pasteurization and in vitro digestion

Soy protein isolate (SPI) and carrageenan (IC) complex coacervates were formed through electrostatic attractions for encapsulating Bifidobacterium longum. The effects of pH (2.0-5.0) and SPI:IC mass ratios (10:1, 15:1, 20:1) on coacervate yield, entrapment efficiency and viability of the probiotic bacteria were investigated. The coacervates produced at pH 3 had higher yields and entrapment efficiency, and a SPI:IC mass ratio of 10:1 produced a complex coacervate with more compact microstructure. Compared to the native ones, the bacteria encapsulated in the coacervates had significantly improved viability during storage (4 °C), pasteurization (85 °C for 5, 10 and 30 min) and in vitro dynamic gastric and intestinal digestion. The findings also suggested that the coacervate with a SPI:IC ratio of 10:1 was more capable to protect the bacteria from loss against different stresses. This study provides a novel approach for designing efficient microcapsules containing probiotic bacteria with enhanced functional properties.