Transparent high internal phase emulsion gels stabilized solely by proteins

Novel high internal phase emulsion gels stabilized solely by hemp protein isolate: Enhancement of cannabidiol chemical stability and bioaccessibility

This study aims to fabricate high internal phase emulsion gels (HIPEGs) using modified hemp protein isolates for microencapsulating cannabidiol (CBD) to enhance their chemical stability and bioaccessibility. Importantly, the combined effect of CBD concentrations (0.1 vs 0.5 wt%) and post gel storage conditions (before-refrigeration (BR) vs after-refrigeration (AR)) on the properties of HIPEGs were investigated. The results showed that the CBD concentration above 0.4 % is necessary to fabricate a stable HIPEG. The rheological properties of HIPEGs were influenced by CBD concentration and refrigeration. The AR gels with 0.5 % CBD showed the highest gel strength (up to 91.7 Pa) and solid-like structures. These properties allowed to HIPEGs maintain good physical stability during storage at 4, 25, and 37 °C for 14 days due to the interconnected polyhedral protein matrices and thick interfacial protein layers. These unique protein architectures offered superior protection against CBD degradation (<2 % of initial added amount) for 100 days during exposure to light and temperature (25 or 37 °C). The INFOGEST digestion results showed the BR gels effectively protected CBD during digestion and consequently improved their stability and bioaccessibility up to 95 % and 74 %, respectively. Overall, the fabricated HIPEGs could be valuable for nutraceutical delivery.

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 %.

A stable delivery system for curcumin: Fabrication and characterization of self-assembling acylated kidney bean protein isolate nanogels

The construction of protein-based nano-gels as curcumin delivery system effectively enhances the stability and bioavailability of curcumin. In this study, acylation modification and self-assembly techniques were jointly employed to construct acylated kidney bean protein isolate (AKBPI)-nanogels. Optimal conditions for AKBPI-nanogels were determined to be pH 7, concentration of 2 mg/mL, and temperature at 90℃ for 30 min. The optimized AKBPI-nanogels exhibited excellent uniformity as evidenced by decreasing average particle size (137.35 nm) and polydispersity index (0.38). Acylation enhanced the intermolecular interactions within the nanogel by reducing the polarity of tyrosine microenvironment and free sulfhydryl groups. AKBPI-nanogels demonstrated remarkable characteristics in terms of pH sensitivity, salt concentration, and storage tolerance. The curcumin-loaded AKBPI-nanogels exhibited an encapsulation efficiency of 92.30 % and maintained high antioxidant activity. In simulated gastrointestinal digestion, AKBPI-nanogels facilitated the controlled release and higher bioavailability of curcumin. Therefore, AKBPI-nanogels can be a stable tool for delivering curcumin.

Pea protein/carboxymethyl cellulose complexes prepared using a pH cycle strategy as stabilizers of high internal phase emulsions for 3D printing

The development of food-grade high internal phase emulsions (HIPEs) for 3D printing and the replacement of animal fats have attracted considerable attention. In this study, in order to improve the rheological properties and stability of pea protein to prepare HIPE, pea protein/carboxymethyl cellulose (pH-PP/CMC) was prepared and subjected to pH cycle treatment to produce HIPEs. The results showed that pH cycle treatment and CMC significantly reduced the droplet size of HIPEs (from 143.33 to 12.10 μm). At higher CMC concentrations, the interfacial tension of the PP solution decreased from 12.84 to 11.71 mN/m without pH cycle treatment and to 10.79 mN/m with pH cycle treatment. The HIPEs with higher CMC concentrations subjected to pH cycle treatment showed shear thinning behavior and higher viscoelasticity and recovered their solid-like properties after being subjected to 50 % strain, indicating that they could be used for 3D printing. The 3D printing results showed that the pH-PP/CMC HIPE with 0.3 % CMC had the finest structure. Our work provides new insights into developing food-grade HIPEs and facilitating their use in 3D printing inks as nutrient delivery systems and animal fat substitutes.

Enhancement of gum Arabic/casein microencapsulation on the survival of Lactiplantibacillus plantarum in the stimulated gastrointestinal conditions

Probiotic products that contain lactobacilli have long histories of safe use as Lactobacillus strains have many physiological functions in the gastrointestinal tract (GIT). However, the viability of probiotics can be affected by food processing and the adverse environment. This study investigated the O/W (Oil-in-water emulsions) emulsions formed by coagulation of casein/GA (Gum Arabic) complexes for Lactiplantibacillus plantarum microencapsulation, and the stability of the strains during gastrointestinal environment were also determined. The results showed that the particle size of the emulsion decreased from 9.72 μm to 5.48 μm when the GA concentration increased from 0 to 2 (w/v), and the emulsion particles were found to be more uniform as observed by CLSM (Confocal Laser Scanning Microscope). The surface of this microencapsulated casein/GA composite forms smooth, dense agglomerates and has high viscoelasticity, which effectively improved casein's emulsifying activity (8.66 ± 0.17 m2/g). After the casein/GA complexes microencapsulation, a higher viable count was detected after gastrointestinal digestion in vitro, and the activity of L. plantarum is more stable (about 7.51 log CFU/mL) during 35 days of storage at 4 °C. The results of study will help to design lactic acid bacteria encapsulation systems based on the GIT environment for the oral delivery strategy.

Development of protein-polyphenol particles to stabilize high internal phase Pickering emulsions by polyphenols' structure

Protein-polyphenol colloidal particles are promising stabilizers for high internal phase Pickering emulsions (HIPPEs). However, the relationship between the structure of the polyphenols and its ability to stabilize HIPPEs has not been studied thus far. In this study, bovine serum albumin (BSA)-polyphenols (B-P) complexes were prepared, and their ability to stabilize HIPPEs was investigated. The polyphenols were bound to BSA via non-covalent interactions. Optically isomeric polyphenols formed similar bonds with BSA, whereas a greater number of trihydroxybenzoyl groups or hydroxyl groups in the dihydroxyphenyl moieties of polyphenols increased the B-P interactions. Polyphenols also reduced the interfacial tension and enhanced the wettability at the oil-water interface. The HIPPE stabilized by BSA-tannic acid complex exhibited the highest stability among the B-P complexes and resisted demixing and aggregation during centrifugation. This study promotes the potential applications of polyphenol-protein colloidal particles-stabilized HIPPEs in the food industry.

Development and characterization of self-emulsifying high internal phase emulsions using endogenous phospholipids from Antarctic krill oil

High internal phase emulsions (HIPEs) have emerged as a promising structured oil system in food industry. This study developed self-emulsifying HIPEs (SHIPEs) using Antarctic krill oil (KO) with endogenous phospholipids as surfactant and algae oil as a diluent. The influence of phospholipids self-assembly on SHIPEs formation was investigated by evaluating the microstructures, particle size, rheological properties, and water distribution. Results demonstrated that the concentration and self-assembly behavior of phospholipids dominated the SHIPEs formation. Optimized SHIPEs with desirable gel properties contained 10 wt% krill oil in the oil phase at an 80 wt% oil phase level. Furthermore, these SHIPEs exhibited excellent performance in 3D printing applications. Hydrated phospholipids formed lamellar network at the oil-water interface, enhancing gel strength by crosslinking oil droplets. These findings shed light on the self-assembly of phospholipids during HIPEs formation and highlight the potential phospholipids-rich marine lipids in SHIPEs for functional food products development.

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.

Biopolymer-based pickering high internal phase emulsions: Intrinsic composition of matrix components, fundamental characteristics and perspective

Pickering HIPEs have received tremendous attention in recent years due to their superior stability and unique solid-like and rheological properties. Biopolymer-based colloidal particles derived from proteins, polysaccharides and polyphenols have been demonstrated to be safety stabilizers for the construction of Pickering HIPEs, which can meet the demands of consumers for "all-natural" products and provide "clean-label" foods. Furthermore, the functionality of these biopolymers can be further extended by forming composite, conjugated and multi-component colloidal particles, which can be used to modulate the properties of the interfacial layer, thereby adjusting the performance and stability of Pickering HIPEs. In this review, the factors affecting the interfacial behavior and adsorption characteristics of colloidal particles are discussed. The intrinsic composition of matrix components and fundamental characteristics of Pickering HIPEs are emphatically summarized, and the emerging applications of Pickering HIPEs in the food industry are reviewed. Inspired by these findings, future perspectives concerning this field are also put forward, including (1) the exploration of the interactions between biopolymers used to produce Pickering HIPEs and target food ingredients, and the influence of the added biopolymers on the flavor and mouthfeel of the products, (2) the investigation of the digestion properties of Pickering HIPEs under oral administration, and (3) the fabrication of stimulus-responsive or transparent Pickering HIPEs. This review will give a reference for exploring more natural biopolymers for Pickering HIPEs application development.

Recent progress in emulsion gels: from fundamentals to applications

Emulsion gels, also known as gelled emulsions or emulgels, have garnered great attention both in fundamental research and practical applications due to their superior stability, tunable morphology and microstructure, and promising mechanical and functional properties. From an application perspective, attention in this area has been, historically, mainly focused on food industries, e.g., engineering emulsion gels as fat substitutes or delivery systems for bioactive food ingredients. However, a growing body of studies has, in recent years, begun to demonstrate the full potential of emulsion gels as soft templates for designing advanced functional materials widely applied in a variety of fields, spanning chemical engineering, pharmaceutics, and materials science. Herein, a concise and comprehensive overview of emulsion gels is presented, from fundamentals to applications, highlighting significant recent progress and open questions, to scout for and deepen their potential applications in more fields.

Formulation and stabilization of high internal phase emulsions: Stabilization by cellulose nanocrystals and gelatinized soluble starch

In this work, high internal phase emulsions (HIPEs) stabilized by naturally derived cellulose nanocrystals (CNC) and gelatinized soluble starch (GSS) were fabricated to stabilize oregano essential oil (OEO) in the absence of surfactant. The physical properties, microstructures, rheological properties, and storage stability of HIPEs were investigated by adjusting CNC contents (0.2, 0.3, 0.4 and 0.5 wt%) and starch concentration (4.5 wt%). The results revealed that CNC-GSS stabilized HIPEs exhibited good storage stability within one month and the smallest droplets size at a CNC concentration of 0.4 wt%. The emulsion volume fractions of 0.2, 0.3, 0.4 and 0.5 wt% CNC-GSS stabilized HIPEs after centrifugation reached 77.58, 82.05, 94.22, and 91.41 %, respectively. The effect of native CNC and GSS were analyzed to understand the stability mechanisms of HIPEs. The results revealed that CNC could be used as an effective stabilizer and emulsifier to fabricate the stable and gel-like HIPEs with tunable microstructure and rheological properties.

Protein-Based High Internal Phase Pickering Emulsions: A Review of Their Fabrication, Composition and Future Perspectives in the Food Industry

Protein-based high internal phase Pickering emulsions (HIPEs) are emulsions using protein particles as a stabilizer in which the volume fraction of the dispersed phase exceeds 74%. Stabilizers are irreversibly adsorbed at the interface of the oil phase and water phase to maintain the droplet structure. Protein-based HIPEs have shown great potential for a variety of fields, including foods, due to the wide range of materials, simple preparation, and good biocompatibility. This review introduces the preparation routes of protein-based HIPEs and summarizes and classifies the preparation methods of protein stabilizers according to their formation mechanism. Further outlined are the types and properties of protein stabilizers used in the present studies, the composition of the oil phase, the encapsulating substances, and the properties of the constituted protein-based HIPEs. Finally, future development of protein-based HIPEs was explored, such as the development of protein-based stabilizers, the improvement of emulsification technology, and the quality control of stabilizers and protein-based HIPEs.

Gel properties of heat-induced transparent hydrogels from ovalbumin by acylation modifications

In this paper, the effects of acylation modification on the gel behavior of ovalbumin (OVA) under heating induction have been investigated. From the obtained results, the acylated OVA hydrogels exhibited superior gelation properties than the native OVA hydrogels (NOVA-G) in terms of light transmission, gel hardness, resilience and water holding capacity. SEM revealed acylation modifications effectively promoted the formation of uniform and dense network structure of OVA hydrogels. The main intermolecular forces of the acylation-modified OVA hydrogels were hydrophobic interactions and hydrogen bonding. FTIR showed that acylation modifications caused 26.2% decrease in α-helix and 59.2% increase in β-sheet content compared to NOVA-G. Furthermore, in-vitro release experiments showed that the release rate of curcumin from acylated OVA hydrogels was significantly delayed. Moreover, the above results have shown that acylation modifications can be considered as an effective method to improve the gelation as well as drug release properties of protein hydrogels.

Edible mayonnaise-like Pickering emulsion stabilized by pea protein isolate microgels: Effect of food ingredients in commercial mayonnaise recipe

Particle stabilized O/W Pickering emulsion has great potential for making egg-free mayonnaise. In this study, we fabricated pea protein isolate (PPI) microgels by gel-breaking method and applied in mayonnaise-like Pickering emulsion. The effects of acetic acid (pH), sodium chloride (NaCl), and sucrose, which are typically used in commercial mayonnaise were studied. The minimum droplet size (47.0 μm) was found below isoelectric point. The NaCl decreased ζ-potential to almost 0 and risen droplet size to 75.9 μm. The sucrose enhanced the emulsion's viscosity while lowering thixotropic recovery rate. Based on droplet size, viscosity, thixotropic recovery, and microstructure; 350 mmol NaCl and 4 wt% sucrose was finally used to make egg-free mayonnaise-like Pickering emulsion, and showed similar properties compared with commercial mayonnaise, and the thixotropy recovery rate was near 100%. A plant-scale test further confirmed the feasibility. The results showed the PPI microgels had a strong application prospect to form egg-free mayonnaise.