Fabrication and characterization of Pickering emulsion gels stabilized by zein/pullulan complex colloidal particles

High internal phase Pickering emulsions stabilized by Zein-hyaluronic acid conjugate particles and their application in active substances protection

In recent years, active substances have been extensively applied in the fields of food, cosmetics, and pharmaceuticals. However, their preservation and transportation have posed challenges due to issues such as oxidation and photodegradation. This study proposes a method for synthesizing Zein-Hyaluronic Acid (Zein-HA) conjugate particles via the Schiff base reaction, utilizing these conjugate particles to encapsulate and protect active substances within a stable emulsion system. Compared to zein, the modified conjugate particles exhibit significantly improved dispersibility, amphiphilicity, interfacial affinity, and emulsifying properties. Consequently, these particles are capable of stabilizing high internal phase Pickering emulsions with an oil phase volume fraction of up to 80 (v/v)%, thereby enabling the carriage of a higher load of active components. Furthermore, the prepared emulsions demonstrate excellent storage stability, resistance to ionic strength (250-2000 mM NaCl), and outstanding antioxidative characteristics. Moreover, after 8 h of UV light exposure, the retention rates of the active substances (curcumin, astaxanthin, and resveratrol) exceed 60 %. Therefore, these emulsions hold substantial potential to be applied as a carrier system in the food, cosmetics, and pharmaceutical industries.

Characteristics and stabilization of Pickering emulsions constructed using myosin from bighead carp (Aristichthys nobilis)

Myosin from bighead carp (Aristichthys nobilis) as a main type of fish protein possesses a good emulsifying ability. However, whether bighead carp myosin (BCM) could construct stable Pickering emulsions is still unclear. Therefore, myosin particles and Pickering emulsions stabilized by bighead carp myosin (BCMPEs) were analyzed. The surface structure of BCM particles at 0.6 mol/L NaCl treatment was uniform and compact with a contact angle of 86.4 ± 2.7°, exhibiting the potential ability to construct O/W Pickering emulsions. The size and flocculation index (FI) of BCMPEs decreased with the increase in BCM concentrations of 1%-4% (w/v). Reversely, the size of BCMPEs increased with the increase in oil-water ratios. BCM particles could uniformly distribute at the oil-water interface to stabilize BCMPEs at a BCM concentration of 4% (w/v) and an oil-water ratio of 6:4 (v/v). This study could help explore fish proteins to construct Pickering emulsions for the deep processing of fish products.

Effects of different solid particle sizes on oat protein isolate and pectin particle-stabilized Pickering emulsions and their use as delivery systems

Oat protein isolate (OPI)/high methoxyl pectin (HMP) complexes (OPP) were prepared to stabilized Pickering emulsions and applied as nutraceutical delivery systems. The different mass ratios and pH changed the interactions between OPI and HMP that caused the different size of OPP. Specifically, smaller particle size of OPP (125.7-297.6 nm) were formed when hydrophobic interactions along with electrostatic forces predominant in OPP (OPI:HMP = 3:1, pH 4, 5). Among these particles, OPP-2 could stabilize Pickering emulsion efficiently through formation of dense interfacial film, which exhibited the highest apparent viscosity and the smallest average droplet size (23.39 μm). Moreover, OPP-2 stabilized Pickering emulsions with superior stability not only exhibited higher encapsulation efficiency of 85.63%, but also could control curcumin release in simulated gastrointestinal fluids to improve curcumin's bioaccessibility. These results verified the possibility of OPP to be a Pickering emulsions stabilizer, and also identified its potential to be a stable delivery system for bioactive compounds.

Antimicrobial guar gum films optimized with Pickering emulsions of zein-gum arabic nanoparticle-stabilized composite essential oil for food preservation

In this study, composite essential oil Pickering emulsion stabilized with zein-gum arabic (GA) nanoparticles (ZGCEO) was prepared to improve the characteristics of guar gum (GG) films. ZGCEO exhibited commendable stability and compatibility with GG, while leading to a noticeable improvement in the light barrier (from 3.98 A mm-1 to 17.09 A mm-1) and water vapor barrier characteristics of GG films, concomitantly mitigating their hydrophilic nature, with decreasing moisture content (from 17.70 % to 10.50 %), water solubility (from 84.41 % to 71.79 %), water vapor permeability (from 5.64 × 10-11 g (m s Pa)-1 to 4.97 × 10-11 g (m s Pa)-1), and an increasing water contact angle (from 69.8° to 94.2°). The addition of 2 % ZGCEO yielded a notable increase in the tensile strength of the GG-ZGCEO films, but the elongation at break decreased with increasing ZGCEO concentration. Moreover, the incorporated ZGCEO demonstrated outstanding antioxidant and antimicrobial characteristics, featuring a slow-release behavior of essential oil. The GG-ZGCEO coating also showed an excellent preservation effect in pork and "Huangguan" pears during storage. Collectively, we substantiated the efficacy of ZGCEO in augmenting the functional attributes of GG films, thereby establishing their potential utility as antimicrobial packaging materials conducive to food preservation.

Ovalbumin/sodium alginate Pickering emulsion: Structural characteristics and its contribution to enhancing the gel properties of Hairtail (Trichiurus haumela) surimi

In this study, ovalbumin (OV) and sodium alginate (SA), two macromolecular complexes, were coagulated into the emulsifier (OV/SA), which stabilized soybean oil by electrostatic interaction, hydrophobic interactions, and hydrogen bonding. The structure of OV/SA and properties of OV/SA Pickering emulsion were investigated. Additionally, the effect of emulsions on the gel and protein properties of hairtail surimi was studied. The results revealed that with the increasing concentration of OV/SA, the particle size and zeta potential value (negative value) of the emulsion initially decreased and then increased, while the rheological properties gradually improved. Compared with the surimi gel directly supplemented with soybean oil, the addition of emulsion enhanced gel strength, whiteness, water holding capacity, and hydrophobic interactions, resulting in a more stable gel network structure. In summary, incorporating emulsion into surimi at the same lipid content not only maintained its gel properties but also improved its color and compensated for lipid loss.

Pickering emulsion gel of polyunsaturated fatty acid-rich oils stabilized by zein-tannic acid green nanoparticles for storage and oxidation stability enhancement

HYPOTHESIS

Poor storage stability and oxidative deterioration are the common drawbacks of edible oils rich in polyunsaturated fatty acids (PUFAs). We hypothesized that the natural zein/tannic acid self-assembly nanoparticles (ZT NPs) could be employed as stabilizers to anchor at the oil-water interface, thus constructing Pickering emulsion gel (PKEG) system for three types of PUFA-rich oils, soybean oil (SO), fish oil (FO) and cod liver oil (CLO), to improve the storage and oxidation stability.

EXPERIMENTS

ZT NPs were prepared by the anti-solvent coprecipitation method, and the three-phase contact angle, FT-IR, and XRD were mainly characterized. To observe the shell-core structure and oil-water interface details of SO/FO/CLO PKEGs by confocal laser scanning microscope and cryo-scanning electron microscope. Accelerated oxidation of FO was performed to assess the protective effect of PKEG on lipids.

FINDINGS

The SO, FO, and CLO PKEGs stabilized by 2 % ZT NPs, with oil fraction (φ = 0.5-0.6), were obtained. PKEGs show high viscoelasticity, clear shell-core structure spatial network structure, and ideal storage stability. Under accelerated oxidation, the degree of oxidative rancidity of FO PKEG was obviously lower than that of free FO. Overall, this work opens up new possibilities for using natural PKEG to prevent oxidative deterioration and prolong the shelf-life of PUFA-rich oils.

Encapsulation of grape seed oil in oil-in-water emulsion using multilayer technology: Investigation of physical stability, physicochemical and oxidative properties of emulsions under the influence of the number of layers

Many studies have shown that grape seed oil (GSO) is one of the vegetable fats that are plentiful in essential fatty acids and can be used as a fat substitute or to modify fat in food products to reduce saturated fatty acids. However, due to its low solubility and high sensitivity to oxidation, it is necessary to develop delivery systems that can distribute GSO in food more effectively. Recently, the preparation of emulsions using the layer-by-layer (LBL) method has many advantages in delivering lipid-soluble functional compounds. This research was used to check the formation of GSO oil-loaded primary, secondary and tertiary multilayer emulsions stabilized by mixture of anionic gelatin, cationic chitosan, and anionic basil seed gum (BSG) as the aqueous phase at pH 5, prepared using a layer-by-layer electrostatic deposition technique. Multilayer emulsions prepared by GSO and a mixture of gelatin, chitosan, and BSG as the aqueous phase at pH 5. Finally, the effect of the number of layers on the physicochemical properties (particle size, viscosity, turbidity, refractive index, and physical stability) and oxidative stability (peroxide value, thiobarbituric acid value, and fatty acid profile) during the storage time (30 days) at two temperatures 25 °C & 4 °C was investigated. Also, the zeta potential and Fourier transform infrared spectroscopy (FTIR) of mono-layer and multi-layer emulsions were investigated. The results revealed that by increasing the number of layers of multi-layer emulsion of GSO, the stability has improved. Thus, the tertiary emulsion has been more effective than the other two emulsions in maintaining the physicochemical characteristics and stability over time (P < 0.001). Morphological characterization and FTIR spectroscopy results confirmed that gelatin, chitosan, and BSG were successfully loaded into the LBL emulsions. This study can improve the original percept of multilayer emulsions and promulgate their potential applications for the entire encapsulation of essential fatty acids to enrich and prevent peroxide attack.

Fat analogue emulsions stabilized by peanut protein microgel particles: microscale and nanoscale structure and stabilization process analysis

BACKGROUND

Biopolymer-based microgels are being regarded increasingly as promising building blocks in food applications. This study aimed to clarify the evolution process of the network for fat analogue emulsions stabilized by peanut protein isolate (PPI) microgel particles. It also investigated the interfacial structure and characteristics of emulsions (50% oil phase, w/w) stabilized by microgels under different pH conditions.

RESULTS

There was an increasing interfacial adsorption capacity for PPI microgels over time (from 85.26% to the maximum of 89.78% at 24 h of storage) due to the aggregation of microgels around droplets and the development of cross-linking microgel chains between adjacent interfaces. The increased β-sheet content (from 35.51% to 41.12%) of adsorbed microgels indicated unfolding and the enhanced aggregation of microgels, which led to stronger droplet interaction. The network evolution observed with different microscopes clarified the transition to a self-supporting emulsion. The uneven adsorption of large microgel aggregates at the oil-water interface promoted larger and deformed droplets, so more fat-like medium internal phase emulsion stabilized by PPI microgel could be obtained by adjusting the microgel pH to 4.5. The interfacial membranes observed by scanning electron microscopy were thicker and coarser at pH 3.0 and 4.5 than those at pH 7.0 and 9.0. The adsorption of PPI microgel aggregates enhanced the structural strength and improved emulsion stability.

CONCLUSION

This work could form a basis for further studies relating physical properties to the design of plant protein-based fat analogues. © 2024 Society of Chemical Industry.

The droplet breakup model and characteristics of pH-shifted peanut protein isolate-high methoxyl pectin stabilised emulsions under ultrasound

The effect of pH on the occurrence states of peanut protein isolate (PPI) and high methoxyl pectin (HMP), and droplet breakup model of the emulsions under ultrasound were studied. Particle size distribution and scanning electron microscopy results showed that PPI-HMP existed a soluble complex at pH 5.0, had no interaction at pH 7.0, and was co-soluble at pH 9.0. Droplet breakup model results revealed that the characteristics of emulsion stabilised by PPI-HMP treated at pH 5.0 was different from that at pH 7.0 and 9.0. The average diameter of the droplet well satisfied the model. According to rheological properties, interface tension, and microstructure, the formation mechanism and characteristics of emulsion stabilised by PPI-HMP treated at pH 5.0 was different from that at pH 7.0 and pH 9.0. The research provided a reference for constructing emulsions using pH-shifted PPI-HMP under ultrasound.

Waste Utilization: Physicochemical characteristics, stability and applications of emulsified Rana chensinensis ovum oil with waste extracts

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The physicochemical characteristics, stability, and potential application of emulsified Rana chensinensis ovum oil was explored.

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The emulsified Rana chensinensis ovum oil was stabilized by Rana chensinensis ovum protein isolates.

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The emulsified Rana chensinensis ovum oil with the waste protein isolates demonstrated promising antioxidation property.

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Oral delivery application of the emulsified Rana chensinensis ovum oil for quercetin delivery.

Rana chensinensis ovum (RCO) is the major waste/by-product of Oviductus Ranae. This study investigated physicochemical characteristics and stability of emulsified Rana chensinensis ovum oil (RCOO) with Rana chensinensis ovum protein isolates (RCOPI) by particle size, zeta potential, scanning electron microscopy (SEM), visual appearance, confocal laser scanning microscopy (CLSM), rheology and antioxidant capacity. The emulsified RCOO demonstrated great stability, antioxidant capacity and rheological properties. The potential application of the emulsified RCOO as a delivery system was studied using quercetin as an example. The stability of encapsulated quercetin was investigated through storage stability, thermal stability and photostability. The bioaccessibility of encapsulated quercetin was explored by in vitro digestion simulation experiments. The results showed the stability and bioaccessibility of quercetin encapsulated in emulsified RCOO was greatly improved. This study showed that the emulsified RCOO is a promising edible delivery system for hydrophobic bio-actives.

Formation and stability of Pickering emulsion gels by insoluble soy peptide aggregates through hydrophobic modification

In this work, a highly stable food-grade Pickering emulsion gels was successfully prepared by hydrophobically modified insoluble soybean peptide aggregates. The relationships between the surface properties of insoluble soybean peptide aggregates and Pickering emulsion gels characteristics were clarified. After modification, the insoluble soybean peptide aggregates with high surface hydrophobicity had small particle size (377 nm), near-neutral wettability (θo/w = 92°) and strong interfacial adsorption capability. These allowed the modified insoluble soybean peptide aggregates to stabilize the oil-water interface and form continuous network surrounding oil droplets, leading to the formation of stable Pickering emulsion gels. Besides, Pickering emulsion gels prepared by insoluble soybean peptide aggregates with higher surface hydrophobicity had smaller droplet size and higher gel strength, and remained stable even after 60 days of storage. The findings suggest a preferable plant protein particle for the preparation of stable Pickering emulsion gels in food industry.

Herb Polysaccharide-Based Drug Delivery System: Fabrication, Properties, and Applications for Immunotherapy

Herb polysaccharides (HPS) have been studied extensively for their healthcare applications. Though the toxicity was not fully clarified, HPS were widely accepted for their biodegradability and biocompatibility. In addition, as carbohydrate polymers with a unique chemical composition, molecular weight, and functional group profile, HPS can be conjugated, cross-linked, and functionally modified. Thus, they are great candidates for the fabrication of drug delivery systems (DDS). HPS-based DDS (HPS-DDS) can bypass phagocytosis by the reticuloendothelial system, prevent the degradation of biomolecules, and increase the bioavailability of small molecules, thus exerting therapeutic effects. In this review, we focus on the application of HPS as components of immunoregulatory DDS. We summarize the principles governing the fabrication of HPS-DDS, including nanoparticles, micelles, liposomes, microemulsions, hydrogels, and microneedles. In addition, we discuss the role of HPS in DDS for immunotherapy. This comprehensive review provides valuable insights that could guide the design of effective HPS-DDS.

Zein/pullulan complex colloidal particle-stabilized Pickering emulsions for oral delivery of polymethoxylated flavones: protection effect and in vitro digestion

BACKGROUND

Polymethoxylated flavones (PMFs) show multiple biological functions, while their high hydrophobicity leads to a low bioaccessibility and limits their wide applications. The design of a reasonable food-grade drug delivery system is an effective strategy to improve the low bioaccessibility of PMFs. In this study, sinensetin, tangeretin and nobiletin were encapsulated in Pickering emulsions stabilized by zein/pullulan complex colloidal particles (ZPPs), and the protection effect and in vitro digestion were characterized.

RESULTS

Rheological analysis revealed that ZPP-Pickering emulsion loading with PMFs maintained a strong gel-like network structure. Moreover, the ability to scavenge free radicals of PMFs was improved by the emulsion delivery system. The antioxidant activity of PMFs encapsulated in Pickering emulsion was positively correlated with the oil volume fraction (φ). ZPP-Pickering emulsion loading with PMFs can effectively delay lipid oxidation, and the φ (70%) of Pickering emulsion showed the most pronounced effects, in which the lipid hydroperoxide content and malondialdehyde content decreased by 64.3% and 38.3% after 15 days of storage, compared with the bulk oil group, respectively. The bioaccessibility of the three PMFs has been increased by ZPP-Pickering emulsion simultaneously and it presented the highest values as its φ was 50%, in which the bioaccessibility of sinensetin, tangeretin and nobiletin increased by 2.5, 3.2 and 3.9 times, compared with the bulk oil group, respectively.

CONCLUSION

Pickering emulsion stabilized by ZPPs is an excellent nutrient delivery system for delivering three PMFs simultaneously and imparting functional properties to bioactive delivery systems. © 2022 Society of Chemical Industry.

Nano-enabled plant-based colloidal delivery systems for bioactive agents in foods: Design, formulation, and application

Consumers are becoming increasingly aware of the impact of their dietary choices on the environment, animal welfare, and health, which is causing many of them to adopt more plant-based diets. For this reason, many sectors of the food industry are reformulating their products to contain more plant-based ingredients. This article describes recent research on the formation and application of nano-enabled colloidal delivery systems formulated from plant-based ingredients, such as polysaccharides, proteins, lipids, and phospholipids. These delivery systems include nanoemulsions, solid lipid nanoparticles, nanoliposomes, nanophytosomes, and biopolymer nanoparticles. The composition, size, structure, and charge of the particles in these delivery systems can be manipulated to create novel or improved functionalities, such as improved robustness, higher optical clarity, controlled release, and increased bioavailability. There have been major advances in the design, assembly, and application of plant-based edible nanoparticles within the food industry over the past decade or so. As a result, there are now a wide range of different options available for creating delivery systems for specific applications. In the future, it will be important to establish whether these formulations can be produced using economically viable methods and provide the desired functionality in real-life applications.

Soy lipophilic protein self-assembled by pH-shift combined with heat treatment: Structure, hydrophobic resveratrol encapsulation, emulsification, and digestion

This study evaluates the effect of pH (pH 3 and 11) and heat treatment (60 °C) in modifying the soybean lipophilic protein (LP) for the development of an encapsulation system to co-deliver resveratrol (Res) and vitamin D3. The structural and functional properties of LP after the modification will change to varying degrees. Meanwhile, Res was loaded into the hydrophobic core of LP, and the resulting Res-loaded structures have a uniform particle size distribution and a high encapsulation efficiency (78%). When the amount of Res encapsulation increases, the emulsification and oxidation resistance of the Pickering emulsion increased; the interfacial tension and interfacial protein adsorption increased to 11.21 mN/m and 97.34%, respectively. During simulated gastrointestinal digestion, the Pickering emulsion prepared with LP-Res nanoparticles at pH 11, 60 °C (pH 11, 60 °C-LP-Res) effectively protected Res and vitamin D3 from degradation or precipitation, indicating a significant increase in bioavailability.

Engineering Emulsion Gels as Functional Colloids Emphasizing Food Applications: A Review

Gels are functional materials with well-defined structures (three-dimensional networks) assembled from the dispersed colloids, and capable of containing a large amount of water, oil, or air (by replacing the liquid within the gel pores), known as a hydrogel, oleogel, and aerogel, respectively. An emulsion gel is a gelled matrix filled with emulsion dispersion in which at least one phase, either continuous phase or dispersed phase forms spatial networks leading to the formation of a semisolid texture. Recently, the interest in the application of gels as functional colloids has attracted great attention in the food industry due to their tunable morphology and microstructure, promising physicochemical, mechanical, and functional properties, and superior stability, as well as controlled release, features for the encapsulated bioactive compounds. This article covers recent research progress on functional colloids (emulsion gels), including their fabrication, classification (protein-, polysaccharide-, and mixed emulsion gels), and properties specifically those related to the gel-body interactions (texture perception, digestion, and absorption), and industrial applications. The emerging applications, including encapsulation and controlled release, texture design and modification, fat replacement, and probiotics delivery are summarized. A summary of future perspectives to promote emulsion gels' use as functional colloids and delivery systems for scouting potential new applications in the food industry is also proposed. Emulsion gels are promising colloids being used to tailor breakdown behavior and sensory perception of food, as well as for the processing, transportation, and targeted release of food additives, functional ingredients, and bioactive substances with flexibility in designing structural and functional parameters.

Recent Advances on Pickering Emulsions Stabilized by Diverse Edible Particles: Stability Mechanism and Applications

Pickering emulsions, which are stabilized by particles, have gained considerable attention recently because of their extreme stability and functionality. A food-grade particle is preferred by the food or pharmaceutical industries because of their noteworthy natural benefits (renewable resources, ease of preparation, excellent biocompatibility, and unique interfacial properties). Different edible particles are reported by recent publications with distinct shapes resulting from the inherent properties of raw materials and fabrication methods. Furthermore, they possess distinct interfacial properties and functionalities. Therefore, this review provides a comprehensive overview of the recent advances in the stabilization of Pickering emulsions using diverse food-grade particles, as well as their possible applications in the food industry.

New insights into food O/W emulsion gels: Strategies of reinforcing mechanical properties and outlook of being applied to food 3D printing

3D printing technology has been widely used in food processing with its advantages of customized food design, personalized nutrition design, and simplified food supply chain. Food emulsion gels have application value and prospects in food 3D printing due to their promising properties, including biodegradability, biocompatibility, as well as dual characteristics of emulsions and biopolymer gels. Food emulsion gels with appropriate mechanical properties, as a new type of food inks, expand the types and functions of the inks. However, food emulsion gels without adequate reinforced mechanical properties may suffer from defects in shape, texture, mouthfeel, and functionality during 3D printing and subsequent applications. Therefore, it is necessary to summarize the strategies to improve the mechanical properties of food emulsion gels. According to the methods of characterizing the mechanical properties of emulsion gels, this article summarizes four strategies for improving the mechanical properties of emulsion gels through two ways: inside-out (reinforcement of interface and reinforcement of cross-linking) and outside-in (physical approaches and environmental regulations), as well as their basic mechanisms. The application status and future research trends of emulsion gels in food 3D printing are finally discussed.