Gelatin microgel-stabilized high internal phase emulsion for easy industrialization: Preparation, interfacial behavior and physical stability

Low gelatin concentration assisted cellulose nanocrystals stabilized high internal phase emulsion: The key role of interaction

Low concentrations of gelatin (0.02-0.20 wt%) were applied to regulate the surface and interface properties of CNC (0.50 wt%) by forming CNC/G complexes. As gelatin concentration increased from 0 to 0.20 wt%, the potential value of CNC/G gradually changed from -44.50 to -17.93 mV. Additionally, various gelatin concentrations led to micromorphology changes of CNC/G complexes, with the formation of particle interconnection at gelatin concentration of 0.10 wt%, followed by network structure and enhanced aggregation at gelatin concentration of 0.15 and 0.20 wt% respectively. The water contact angle (25.91°-80.23°) and interface adsorption capacity of CNC/G were improved due to hydrophobic group exposure of gelatin. When gelatin concentration exceeded 0.10 % at a fixed oil phase volume fraction (75 %), a high internal phase emulsion (HIPE) stabilized by CNC/G can be formed with a good storage stability. The rheological and microstructure results of HIPE confirmed that low gelatin concentration can assist CNC to form stable emulsion structure. Especially, the auxiliary stabilization mechanism of various gelatin concentration was different. CNC/G-0.10 % and CNC/G-0.15 % stabilized HIPE mainly depended on the enhanced interface adsorption and network structure, while CNC/G-0.20 % stabilized HIPE mainly relied on enhanced interface adsorption/accumulation due to weak electrostatic repulsion and aggregate granular morphology of CNC/G-0.20 %.

Effect of a collagen peptide-fish oil high internal phase emulsion on the printability and gelation of 3D-printed surimi gel inks

The effect of a high internal phase emulsion (HIPE) on three-dimensional-printed surimi gel inks was studied. Increasing the concentration of collagen peptide decreased the particle size of HIPE droplets and improved the viscoelasticity and stability. For example, when the collagen peptide concentration was 5 wt%, the viscoelasticity of the HIPE was high, as indicated by the presence of small and uniform particles, which formed a monolayer in the outer layer of the oil droplets to form stable a HIPE. A HIPE was used as the filling material to fill the surimi gel network, which reduced the porosity of the network. Surimi protein and peptides have dual emulsifying effects on the stabilization of oil. After adding the emulsion, the texture, gel properties and rheological properties of the surimi were reduced, and its printing adaptability was improved. This study provides new ideas for the production of surimi and its application in 3D printing.

Gelatin-nanocellulose stabilized emulsion-filled hydrogel beads loaded with curcumin: Preparation, encapsulation and release behavior

In this study, the curcumin was firstly encapsulated in gelatin (GLT) and/or cellulose nanocrystals (CNC) stabilized emulsions, then further mixed with sodium alginate (SA) to form emulsion-filled hydrogel beads loaded with curcumin (Cur). The Cur-loaded emulsions showed a droplet size of 20.3-24.4 μm with a uniform distribution. Introducing CNC and/or SA increased the viscosity of emulsions accompanied by viscoelastic transition, while the modulus was reduced due to destruction of GLT gel. Cur was doubly immobilized in the hydrogel beads with >90 % of encapsulation efficiency. The results of simulated gastrointestinal tract experiments revealed that the beads possessed a good pH sensitivity and controlled release behavior to prolong the retention of Cur in the gastrointestinal tract. After 6 h of UV irradiation, the Cur-loaded emulsion-filled hydrogel beads showed a higher antioxidant activity than that of pure Cur, effectively delaying the photodegradation of Cur. In addition, the beads had better stability in aqueous and acidic environments, which was favorable for prolonging the release of Cur. These results suggest that the emulsion-filled hydrogel beads have great potential for the delivery of lipophilic bioactive molecules.

Effect of NaCl concentration on the formation of high internal phase emulsion based on whey protein isolate microgel particles

At present, the effect of structural modification of microgel particles on high internal phase emulsions (HIPEs) is less studied. In this study, the structural modification effect of NaCl on whey protein isolate microgels (WPIMPs) was comprehensively characterized and applied to the construction of HIPEs. WPIMPs were prepared with NaCl (0-150 mM) and the structural changes were analyzed by measuring the particle size, Zeta-potential, and endogenous fluorescence spectra. The results showed that inducing WPIMPs by NaCl enhanced the surface hydrophobicity, decreased the Zeta potential, and elevated the degree of cross-linking. The interfacial behavior of WPIMPs was characterized by measuring interfacial tensions and adsorbed layer properties. The results showed that NaCl induction decreased the interfacial tension, increased the thickness of the adsorbed layer, and improved the viscoelasticity. The HIPEs were analyzed for micromorphology and particle sizes. The results indicated that NaCl-induced WPIMPs favored the formation of HIPEs with small particle sizes and provided HIPEs with superior environmental stability. This study provides a new idea for the structural modification of microgels and a new theoretical basis for the construction conditions of HIPE.

Thermal Stability Improvement of Core Material via High Internal Phase Emulsion Gels

Biocompatible particle-stabilized emulsions have gained significant attention in the biomedical industry. In this study, we employed dynamic high-pressure microfluidization (HPM) to prepare a biocompatible particle emulsion, which effectively enhances the thermal stability of core materials without the addition of any chemical additives. The results demonstrate that the HPM-treated particle-stabilized emulsion forms an interface membrane with high expansion and viscoelastic properties, thus preventing core material agglomeration at elevated temperatures. Furthermore, the particle concentration used for constructing the emulsion gel network significantly impacts the overall strength and stability of the material while possessing the ability to inhibit oxidation of the thermosensitive core material. This investigation explores the influence of particle concentration on the stability of particle-stabilized emulsion gels, thereby providing valuable insights for the design, improvement, and practical applications of innovative clean label emulsions, particularly in the embedding and delivery of thermosensitive core materials.

Regulation mechanism of ionic strength on the ultra-high freeze-thaw stability of myofibrillar protein microgel emulsions

The regulation mechanism of ionic strength (0-1000 mM) on the freeze-thaw (FT) stability of emulsions stabilized by myofibrillar protein microgel particles (MMP) was systematically investigated. High ionic strength emulsions (300-1000 mM) exhibited stability after five FT cycles. With ionic strength increasing, the repulsive force between particles gradually reduced, the flocculation degree (20.72 ∼ 75.60%) and apparent viscosity of emulsions gradually rose (69 ∼ 170 mPa·s), promoting the formation of protein network structures in the continuous phase. Concurrently, the interfacial proteins rearranged (18.8 ∼ 104.2 s^-1) and aggregated rapidly, facilitating the formation of a stable interface network structure, ultimately improving its stability. Besides, scanning electron microscopy (SEM) images revealed that the interfacial proteins gradually aggregated, further forming a network with the MMP in the continuous phase, allowing MMP emulsions with enhanced FT stability at high ionic strength (300-1000 mM). This study was beneficial to produce emulsion-based sauces with ultra-high FT stability.

Molecular mechanisms affecting the stability of high internal phase emulsions of zein-soy isoflavone complexes fabricated with ultrasound-assisted dynamic high-pressure microfluidization

In this study, zein-soy isoflavone complex (ZSI) emulsifiers were fabricated using ultrasound-assisted dynamic high-pressure micro fluidization to stabilise highinternal phase pickering emulsions. Ultrasound-assisted dynamic high-pressure micro-fluidization enhanced surface hydrophobicity, zeta potential, and soy isoflavone binding capacity, while it decreased particle size, especially during ultrasound and subsequent microfluidization. The treated ZSI could produce small droplet clusters and gel-like structures, with excellent viscoelasticity, thixotropy and creaming stability owing to their neutral contact angles. Ultrasound and subsequent micro fluidization treatment of the ZSI complexes were highly effective in preventing droplet flocculation and coalescence after long-term storage or centrifugation due to their higher surface load, thicker multi-layer interfacial structure, and stronger electronic repulsion between the oil droplets. This study provides insights and extends our current knowledge of how non-thermal technology affects the interfacial distribution of plant based particles and the physical stability of emulsions.

Advances in preparation and application of food-grade emulsion gels

Emulsion gel is a semi-solid or solid material with a three-dimensional net structure produced from emulsion through physical, enzymatic, chemical methods or their combination. Emulsion gels are widely used in food, pharmaceutical and cosmetic industries as carriers of bioactive substances and fat substitutes due to their unique properties. The modification of raw materials, and the application of different processing methods and associated process parameters profoundly affect the ease or difficult of gel formation, microstructure, hardness of the resulting emulsion gels. This paper reviews the important research undertaken in the last decade focusing on classification of emulsion gels, their preparation methods, the influence of processing method and associated process parameters on structure-function of emulsion gels. It also highlights current status of emulsion gels in food, pharmaceutical and medical industries and provides future outlook on research directions requiring to provide theoretical support for innovative applications of emulsion gels, particularly in food industry.

High Internal Phase Emulsions Stabilized by Pea Protein Isolate Modified by Ultrasound Combined with pH-Shifting: Micromorphology, Rheology, and Physical Stability

In this study, the interfacial behavior of high internal phase emulsions (HIPEs), stabilized by ultrasound combined with pH-shifting modified pea protein isolate (MPPI), was investigated, and its emulsification process and stabilization mechanism were discussed. The effects of MPPI concentration on the micromorphology, droplet size, rheology, and stability of HIPEs were investigated. As the MPPI concentration increased, the appearance of HIPEs gradually changed from a relatively fluid state to a plastic solid-like state with detailed texture. There occurred a gradual decrease in droplet size, the cohering of an orderly and tight arrangement, in addition to the formation of a bilayer elastic interface layer. The macro- and microrheological assessments confirmed that the apparent viscosity, storage modulus, elasticity index, and macroscopic viscosity index increased gradually. Furthermore, it was demonstrated that 5 wt% MPPI-stabilized HIPEs had the potential to be used as 3D printing inks. Stability evaluation showed that the TURBISCAN stability index decreased and centrifugal stability increased. The appearance and microstructure remained highly stable after heating at 80 °C for 30 min and storage at 4 ℃ for 90 days. These findings confirm that MPPI improves the rheological behavior and stability of HIPEs by modulating the interfacial adsorption and network structure.

Effect of Potato Starch Hydrogel:Glycerol Monostearate Oleogel Ratio on the Physico-Rheological Properties of Bigels

Bigel (BG) has been shown to be promising for the food industry due to the possibility to manipulate the properties of the system by adjusting the ratio of each individual phase, namely the hydrogel (H) and oleogel (O) phases. This work aimed to evaluate the influence of the O:H ratio on the physical-rheological properties of BG produced with potato starch (PS) and glycerol monostearate (GM). The hydrogel hardness (i.e., 1423.47 g) directly influenced the viscosity of the BG samples, as BG with a higher H-phase presented the highest viscosity and firmness. All BG samples presented shear-thinning behavior and structural breakdown at ~50 °C. BG with a higher O-phase had superior results for thermal stability, softer texture, and yield stress values, representative of good plasticity and spreadability, as compared to BG with less O-phase. The BG with 80% H-phase was less stable during the 21 days of storage in relation to the other BG samples. This study showed the role that the O:H ratio plays in the development of PS-GM-based BGs with tailor-made physical-rheological properties. In addition, the BG is an easily reproduced system with great potential to be used as a trans and saturated fat substitute in food applications.

Research Progress of Food-Grade High Internal Phase Pickering Emulsions and Their Application in 3D Printing

High internal phase Pickering emulsion (HIPPE) is a type of emulsion stabilized by solid particles irreversibly adsorbed on an interfacial film, and the volume fraction of the dispersed phase (Φ) is larger than the maximum packing volume fraction (Φ_max). Proteins, polysaccharides, and their composite particles can be used as good particle stabilizers. The contact angle can most intuitively demonstrate the hydrophilicity and hydrophobicity of the particles and also determines the type of emulsions (O/W or W/O type). Particles' three-phase contact angles can be adjusted to about 90° by compounding or modification, which is more conducive to emulsion stability. As a shear thinning pseudoplastic fluid, HIPPE can be extruded smoothly through 3D printer nozzles, and its high storage modulus can support the structure of printed products. There is huge potential for future applications in 3D printing of food. This work reviewed the biomacromolecules that can be used to stabilize food-grade HIPPE, the stabilization mechanism of the emulsions, and the research progress of food 3D printing to provide a reference for the development of advanced food products based on HIPPE.