Food-grade Pickering emulsions stabilized by ovotransferrin fibrils

Novel reaction systems for catalytic synthesis of structured phospholipids

Phospholipids are distinctive, adaptable molecules that are crucial to numerous biological systems. Additionally, their various architectures and amphiphilic characteristics support their unrivaled crucial functions in scientific and industrial applications. Due to their enormous potential for use in the fields of medicine, food, cosmetics, and health, structured phospholipids, which are modified phospholipids, have garnered increased attention. Traditional extraction methods, however, are pricy, resource-intensive, and low-yielding. The process of enzyme-catalyzed conversion is effective for producing several types of structured phospholipase. However, most frequently employed catalytic procedures involve biphasic systems with organic solvents, which have a relatively large mass transfer resistance and are susceptible to solvent residues and environmental effects due to the hydrophobic nature of phospholipids. Therefore, the adoption of innovative, successful, and environmentally friendly enzyme-catalyzed conversion systems provides a new development route in the field of structured phospholipids processing. Several innovative catalytic reaction systems are discussed in this mini-review, including aqueous-solid system, mixed micelle system, water-in-oil microemulsion system, Pickering emulsion system, novel solvent system, three-liquid-phase system, and supercritical carbon dioxide solvent system. However, there is still a glaring need for a thorough examination of these systems for the enzymatic synthesis of structural phospholipids. In terms of the materials utilized, applicability, benefits and drawbacks, and comparative effectiveness of each system, this research establishes further conditions for the system's selection. To create more effective biocatalytic processes, it is still important to build green biocatalytic processes with improved performance. KEY POINTS: • The latest catalytic systems of phospholipase D are thoroughly summarized. • The various systems are contrasted, and their traits are enumerated. • Different catalytic systems' areas of applicability and limitations are discussed.

Fabrication, characterization and application of Pickering emulsion gels stabilized by defatted grape seed powder

The feasibility of defatted grape seed powder (DGSP) stabilizing Pickering emulsion gels as butter substitute was investigated. The Pickering emulsion gel was constructed using DGSP through high-speed homogenization, and the effects of particle concentration (c) and oil-phase (Medium chain triglyceride) volume fraction (φ) on its structure and properties were investigated. Its application as a butter substitute was also evaluated. The results showed that DGSP had various particle shapes, a wide particle size distribution (3-130 μm), and a three-phase contact angle of 128.9 ± 2.3°. The O/W Pickering emulsion gels with φ ≥ 60% could be obtained at c ≥ 2%. The droplet diameter was negatively correlated with c and positively correlated with φ, while the gel strength was positively related to c and φ. The resulting emulsion gel demonstrated solid-like viscoelastic behavior and pseudoplasticity, and had the potential to serve as a butter substitute. The results can promote the application of grape seeds in food.

Effects of rice bran rancidity on the interfacial adsorption properties of rice bran protein fibril aggregates and stability of high internal phase Pickering emulsions

The effects of rice bran rancidity-induced protein oxidation and heating time on the stability of rice bran protein fibril aggregates (RBPFA)-high internal phase Pickering emulsions (HIPPEs) were investigated. The optimal conditions for RBPFA-HIPPEs were 8 mg/mL RBPFA with an oil phase volume fraction of 75 %. Moderate oxidation (rice bran stored for 3 d) and moderate heating (8 h) enhanced the wettability, flexibility, diffusion rate, and adsorption rate of RBPFA, meanwhile, the rheological properties of RBPFA-HIPPEs increased. RBPFA-HIPPEs could be stably stored for 50 d at 25 °C. Moderate oxidized and moderate heated RBPFA-stabilized HIPPEs could remain stable after heat treatment and could be re-prepared after freeze-thaw (3 cycles). Additionally, the stability of RBPFA-HIPPEs was significantly related to the structural characteristics and interfacial properties of RBPFA. Overall, moderate oxidation and moderate heating enhanced the storage, thermal, and freeze-thaw stability of RBPFA-HIPPEs by improving the interfacial properties of RBPFA.

Pickering emulsions with high ionic strength resistance stabilized by pea protein isolate-polyglycerol conjugate particles with good biocompatibility

Among various biopolymers, protein particles are widely used for stabilizing Pickering emulsions, yet their emulsifying ability are easily influenced by the ion concentration, pH, and high temperatures. To address these challenges, this study utilized chemical modification to prepare pea protein isolate-polyglycerol (PPI-PG) conjugates by Schiff-base reaction. Compared with other chemical modifications, this method produces conjugate particles with excellent biocompatibility, capable of promoting cell proliferation by up to 177 %. These conjugates showed improved dispersibility, with diffusion coefficients 3.5 times greater than pure PPI, and the isoelectric points shift from pH 4.6 to pH 1.5, which contribute to the pH stability of emulsions (pH 3-9). Additionally, the anisotropic nature of the conjugate particles, with a three-phase contact angle close to 90°, make particles need more energy for detachment from the oil-water interface, leading to good thermal stability of emulsion (80 °C, 48 h). Notably, after conjugation, these particles rely more on PG chains for dispersibility, which are less affected by ions, resulting in emulsions with high ionic strength resistance (3000 mM). Furthermore, the prepared Pickering emulsion demonstrates remarkable antioxidative properties (only a 10 % decrease), indicating widely potential applications in food, cosmetics, and pharmaceutical sectors.

Effect of xanthan gum (XG) and carrageenan (CG) ratio on casein (CA)-XG-CG ternary complex: Used to improve the stability of liquid diabetes formula food for special medical purposes

Poor storage stability limits the application of liquid diabetes formula food for special medical purposes (L-D-FSMP) in maintaining blood sugar stability in diabetic patients. This work aims to improve the stability of L-D-FSMP by adjusting the ratio of xanthan gum (XG) and carrageenan (CG) in casein (CA)-XG-CG ternary complex. The centrifugal sedimentation rate results showed that the compound ratio of XG and CG had a greater impact on L-D-FSMP storage stability. Transmission electron microscopy (TEM) results showed that the combination of CA, XG and CG occurred. Fourier transform infrared spectroscopy (FTIR) results showed that CA, XG and CG were mainly combined through hydrogen bonds and ionic bonds to form a CA-XG-CG ternary complex. When the ratio of XG and CG was 1:1, the number of disulfide bonds was the largest. The results of three-phase contact angle and emulsifying ability confirmed that when the ratio of XG and CG was 1:1, CA-XG-CG had the strongest emulsifying ability. The particle size distribution and zeta-potential results showed that when the ratio of XG and CG was 1:1, L-D-FSMP had the narrowest particle size distribution range and the strongest stability. These results may provide valuable information for the production of stable L-D-FSMP.

All-natural polysaccharide and protein complex nanoparticles from Clitocybe squamulosa as unique Pickering stabilizers for oil-in-water emulsions

This study aimed to develop novel nanoparticles that can serve as an excellent oil-in-water (O/W) Pickering stabilizer. The polysaccharide-protein complex nanoparticles (PPCNs-20 and PPCNs-40) were prepared at different ultrasonication amplitudes (20 % and 40 %, respectively) from the polysaccharide-protein complexes (PPCs) which were extracted from the residue of Clitocybe squamulose. Compared with PPCs and PPCNs-20, the PPCNs-40 exhibited dispersed blade and rod shape, smaller average size, and larger zeta potential, which indicated significant potential in O/W Pickering emulsion stabilizers. Subsequently, PPCNs-40 stabilized Pickering emulsions were characterized at different concentrations, pHs, and oil phase contents. The average size, micromorphology, rheological properties, and storage stability of the emulsions were improved as the concentration of PPCNs-40, the ratio of the soybean oil phase and pH value increased. Pickering emulsions showed the best stability when the concentration of PPCNs-40 was 3 wt%, and the soybean oil fraction was 30 % under both neutral and alkaline conditions. The emulsions demonstrated shear thinning and gelation behavior. These findings have implications for the use of eco-friendly nanoparticles as stabilizers for Pickering emulsions and provide strategies for increasing the added value of C. squamulosa.

Self-Assembled Nanocarrier Delivery Systems for Bioactive Compounds

Although bioactive compounds (BCs) have many important functions, their applications are greatly limited due to their own defects. The development of nanocarriers (NCs) technology has gradually overcome the defects of BCs. NCs are equally important as BCs to some extent. Self-assembly (SA) methods to build NCs have many advantages than chemical methods, and SA has significant impact on the structure and function of NCs. However, the relationship among SA mechanism, structure, and function has not been given enough attention. Therefore, from the perspective of bottom-up building mechanism, the concept of SA-structure-function of NCs is emphasized to promote the development of SA-based NCs. First, the conditions and forces for occurring SA are introduced, and then the SA basis and molecular mechanism of protein, polysaccharide, and lipid are summarized. Then, varieties of the structures formed based on SA are introduced in detail. Finally, facing the defects of BCs and how to be well solved by NCs are also elaborated. This review attempts to describe the great significance of constructing artificial NCs to deliver BCs from the aspects of SA-structure-function, so as to promote the development of SA-based NCs and the wide application of BCs.

Recent progress on Pickering emulsion stabilized essential oil added biopolymer-based film for food packaging applications: A review

Nowadays food safety and protection are a growing concern for food producers and food industry. The stability of food-grade materials is key in food processing and shelf life. Pickering emulsions (PEs) have gained significant attention in food regimes owing to their stability enhancement of food specimens. PE can be developed by high and low-energy methods. The use of PE in the food sector is completely safe as it uses solid biodegradable particles to stabilize the oil in water and it also acts as an excellent carrier of essential oils (EOs). EOs are useful functional ingredients, the inclusion of EOs in the packaging film or coating formulation significantly helps in the improvement of the shelf life of the packed food item. The highly volatile nature, limited solubility and ease of oxidation in light of EOs restricts their direct use in packaging. In this context, the use of PEs of EOs is suitable to overcome most of the challenges, Therefore, recently there have been many papers published on PEs of EOs including active packaging film and coatings and the obtained results are promising. The current review amalgamates these studies to inform about the chemistry of PEs followed by types of stabilizers, factors affecting the stability and different high and low-energy manufacturing methods. Finally, the review summarizes the recent advancement in PEs-added packaging film and their application in the enhancement of shelf life of food.

Ovotransferrin Fibril-Gum Arabic Complexes as Stabilizers for Oleogel-in-Water Pickering Emulsions: Formation Mechanism, Physicochemical Properties, and Curcumin Delivery

This project aimed to explore the influence of the interaction between ovotransferrin fibrils (OTF) and gum arabic (GA) on the formation mechanism, physicochemical properties, and curcumin delivery of the oleogel-in-water Pickering emulsion. Cryo-scanning electron microscopy results showed that OTF-GA complexes effectively adsorbed on the oil-water interface, generating spatial hindrance to inhibit droplet coalescence. The texture analysis also proved that OTF-GA complexes endowed oleogel-in-water Pickering emulsion with preferable springiness (0.49 ± 0.03 mm), chewiness (0.43 ± 0.07 mJ), and adhesion (0.31 ± 0.01 mJ). By exploring the coalescence stability, droplet size, and rheological properties of OTF-GA complexes-stabilized oleogel-in-water Pickering emulsion (OGPE), the higher coagulation stability, larger average droplet size (46.22 ± 0.08 μm), and stronger gel strength were observed. The microrheological results also exhibited stronger attraction between the OGPE droplets, a more pronounced solid-like structure, and a slower speed of movement than OTF-stabilized oleogel-in-water Pickering emulsion (OPE). Meanwhile, OGPE significantly enhanced the extent of lipolysis, stability, and bioaccessibility of curcumin, suggesting that it possessed superior performance as a delivery system for bioactive substances. This project provided adequate theoretical references for protein-polysaccharide complexes-stabilized oleogel-in-water Pickering emulsion, and contributed to expanding the application of oleogel-in-water Pickering emulsion in the food industry.

Fabrication and characterization of anthocyanin-loaded double Pickering emulsions stabilized by β-cyclodextrin

Anthocyanins, one of the important water-soluble pigments, are sensitive to environmental factors, which limits the application of anthocyanins in food field. In order to overcome this limitation, double Pickering emulsions stabilized by β-cyclodextrin were developed. The optimum preparation conditions of the emulsions were determined firstly and the performance and structure of emulsions were investigated. Results showed that the optimum preparation conditions of emulsions were the ratio of (W1/O): W2 = 6:4 and 4 % β-cyclodextrin concentration. Optical microscope and confocal laser scanning microscope results confirmed that β-cyclodextrin adsorbed onto the surface of droplets forming stable double Pickering emulsions structure. In vitro gastrointestinal digestion experiments proved that double Pickering emulsions played a controlled-release effect in the small intestine. Rheological analysis proved that the emulsions exhibited elastic properties and demonstrated shear thinning behavior. The emulsions showed excellent stability under centrifugation and thermal conditions. These findings will promote anthocyanins' application in daily diet.

Stability and programmed sequential release of Lactobacillus plantarum and curcumin encapsulated in bilayer-stabilized W1/O/W2 double emulsion: Effect of pectin as protective shell

In order to overcome the problem that traditional W1/O/W2 double emulsions do not have targeted release performance, thereby better meeting the health needs of consumers, ovalbumin fibrils/pectin-based bilayer-stabilized double emulsion (OP-BDE) co-encapsulated with Lactobacillus plantarum and curcumin was constructed with pectin as the outer protective shell, which was expected to be used in the development of novel functional foods. The effects of pectin coating on the viability of Lactobacillus plantarum under conditions including storage, pasteurization, freeze-thaw cycles and in vitro simulated digestion were investigated. Results showed that pectin as protective shell could significantly enhance the tolerance of Lactobacillus plantarum to various environmental factors. Besides, the adsorption of pectin endowed OP-BDE with higher lipolysis and stronger protective effect on curcumin, remarkably improving the photostability and bioaccessibility of curcumin. In addition, in vitro simulated gastrointestinal release study indicated that OP-BDE possessed programmed sequential release property, allowing curcumin and Lactobacillus plantarum to be released in small intestine and colon, respectively. OP-BDE is the first reported co-delivery emulsion system with programmed release characteristic. This study provides new insights into OP-BDE in constructing co-delivery systems and programmed sequential release of active substances, and has potential reference and application value in actual food production.

Black garlic particles as a natural pigment and emulsifier in a Pickering emulsion based low fat innovative mayonnaise: Improved rheology and bioactivity

Black garlic is rich in brown pigments and Maillard reaction products are known for antioxidant activity and health promoting effects. In the present investigation, we report a facile strategy for fabricating low-fat innovative mayonnaise (IM) using black garlic particles (BGP) as a natural pigment, and a functional ingredient. Whey protein concentrate and high methoxyl pectin at optimized concentrations were utilized for fabricating an IM which served as a control. IM5 and IM10 were ternary composites constituting whey protein, high methoxyl pectin along with BGP (@5 and 10% respectively). The formulation IM10 (BGP @10%) showed high firmness and low spreadability quotient, hence IM5 was taken forward for fabrication for two more variants namely IM-J (using low methoxyl pectin (LMP) from jackfruit peels) and IM-C (LMP from citrus). The effect of BGP and LMP on the functional quality of IM was confirmed through zeta potential, antioxidant activity, textural, rheological, and microscopic evaluation. Fluorescence microscopy confirmed the presence of solid particles over the fat phase of IM, while interaction of pectin and whey proteins was demonstrated through fluorescence emission spectroscopy which clearly displayed stabilization of IM through the formation of Pickering emulsion. Pronounced difference in color and flavor score with BGP established high sensory scores in IM5, IM-J, and IM-C. Rheology supported the stabilizing effects of LMP in IM-J and IM-C in terms of speedy recovery of thixotropy, with recovering storage modulus (G'). Enhanced viscosity of IM-C and IM-J further corroborated the dual effect of LMP and BGP in improving emulsifying and functional quality of IM. Enhanced oxidative stability of IM was established by reduced peroxide and Totox values. Overall our results suggest the promising applications of black garlic as functional ingredient in protein and pectin based Pickering emulsions.

Biogenic engineered nanomaterials for enhancing bioavailability via developing nano-iron-fortified smart foods: advances, insight, and prospects of nanobionics in fortification of food

Iron deficiency is a significant cause of iron deficiency anemia (IDA). Treatment of IDA is challenging due to several challenges, including low target bioavailability, low palatability, poor pharmacokinetics, and extended therapeutic regimes. Nanotechnology holds the promise of revolutionizing the management and treatment of IDA. Smart biogenic engineered nanomaterials (BENMs) such as lipids, protein, carbohydrates, and complex nanomaterials have been the subject of extensive research and opened new avenues for people and the planet due to their enhanced physicochemical, rheological, optoelectronic, thermomechanical, biological, magnetic, and nutritional properties. Additionally, they show eco-sustainability, low biotoxicity, active targeting, enhanced permeation and retention, and stimuli-responsive characteristics. We examine the opportunities offered by emerging smart BENMs for the treatment of iron deficiency anemia by utilizing iron-fortified smart foods. We review the progress made so far and other future directions to maximize the impact of smart nanofortification on the global population. The toxicity effects are also discussed with commercialization challenges.

Design of Novel Knot-like Structures Based on Ovotransferrin Fibril-Gum Arabic Complexes: Effective Strategies to Stabilize Pickering Emulsions

This work aimed to clarify the effects of gum arabic (GA) on the morphology and properties of ovotransferrin fibrils (OVTFs). By constructing OVTF-GA complexes and exploring the dispersion stability, turbidity and the ζ-potential of the complexes, the optimum mass ratio of OVTFs to GA and pH for complex formation were confirmed as being 1:1 and pH 4.6, respectively. The interaction between OVTFs and GA was determined to be predominantly driven by electrostatic attraction. The OVTF-GA complexes exhibited a knot-like structure when observed using atomic force microscopy. Then, OVTFs and OVTF-GA complexes were compared in terms of contact angle, surface hydrophobicity and dynamic interfacial tension. The combination of OVTFs and GA decreased the contact angle of OVTFs from 80.85° to 70.36°. In comparison with OVTFs, OVTF-GA complexes reduced the oil-water interfacial tension to a lower level (8.14 mN/m). Furthermore, the capacities of OVTF-GA complexes in stabilizing emulsions were explored. OVTF-GA complex-stabilized oleogel-based Pickering emulsion (OGPE) was constructed, and OVTF-stabilized oleogel-based Pickering emulsion (OPE) was used as the control. OGPE had a higher emulsified phase volume fraction (EPVF) and stability index (SI). The EPVF of OGPE was 100.0% and 99.4% before and after one-month storage, respectively, compared with 98.3% and 95.7% of OPE. This work can provide some useful references for the design of biopolymers with novel structures composed of protein fibrils and polysaccharides, which may also help to construct and apply protein fibril-polysaccharide complexes under specific needs.

Optimization of food-grade colloidal delivery systems for thermal processing applications: a review

Colloidal delivery systems are widely used in the food industry to enhance the dispersibility, stability, efficacy, or bioavailability. However, when exposed to the high temperature, delivery systems are often prone to degradation, which limits its application in thermal processing. In this paper, the effects of thermal processing on the performance of traditional protein-based or starch-based delivery systems are firstly described, including the molecular structure changes of proteins, starches or lipids, and the degradation of embedded substances. These effects are unfavorable to the application of the delivery system in thermal processing. Then, strategies of improving the heat resistance of food grade colloid delivery system and their use in frying, baking and cooking food are mainly introduced. The heat resistance of the delivery system can be improved by a variety of strategies, including the development of new heat-resistant materials, the addition of heat-resistant coatings to the surface of delivery systems, the cross-linking of proteins or starches using cross-linking agents, the design of particle structures, the use of physical means such as ultrasound, or the optimization of the ingredient formula. These strategies will help to expand the application of heat-resistant delivery systems so that they can be used in real thermal processing.

Ultrastable Emulsion Stabilized by the Konjac Glucomannan-Xanthan Gum Complex

Surfactant-free emulsions are currently gaining increased interest due to their technofunctional, health-promoting, economic, biocompatible, and sustainable characteristics. Herein, we report an ultrastable, surfactant-free emulsion stabilized by the konjac glucomannan (KGM)-xanthan gum (XG) complex. The results suggested that KGM-XG tended to adsorb onto the oil/water interface, causing a reduction in interfacial tension. The emulsion droplets were less than 1 μm in diameter and had a narrow size distribution. Using laser confocal microscopy and cryo-SEM, it was observed that KGM-XG generated a compact film on the surface of emulsion droplets while simultaneously constructing a three-dimensional network in the continuous phase. Both of these factors contributed to the stability of the emulsion. The present study presents a straightforward approach for producing highly stable emulsions stabilized by polysaccharides. These emulsions can be effectively utilized to enhance the water resistance of cellulose paper, which is extensively employed in the packaging industry.

Physicochemical properties and in vitro digestion behavior of emulsion gels stabilized by rice bran protein aggregates: Effects of heating time and induction methods

To investigate the effects of heating time and induction methods on the physicochemical properties and in vitro digestion behavior of emulsion gels, rice bran protein aggregates (RBPAs) were formed by acid-heat induction (90 °C, pH 2.0) and the emulsion gels were further prepared by adding GDL or/and laccase for single/double cross-linked induction. Heating time affected the aggregation and oil/water interfacial adsorption behavior of RBPAs. Suitable heating (1-6 h) was conducive to faster and more adsorption of aggregates at the oil/water interface. While excessive heating (7-10 h) resulted in protein precipitation, which inhibited the adsorption at the oil/water interface. The heating time at 2, 4, 5 and 6 h was thus chosen to prepare the subsequent emulsion gels. Compared with the single cross-linked emulsion gels, the double-cross-linked emulsion gels showed higher water holding capacity (WHC). After simulated gastrointestinal digestion, the single/double cross-linked emulsion gels all exhibited slow-release effect on free fatty acid (FFA). Moreover, the WHC and final FFA release rate of emulsion gels were closely related to the surface hydrophobicity, molecular flexibility, sulfhydryl, disulfide bond and interface behavior of RBPAs. Generally, these findings proved the potential of emulsion gels in designing fat alternatives, which could provide a novel technique for the fabrication of low-fat food.

Raman Spectroscopy of Emulsions and Emulsion Chemistry

Emulsions are dispersed systems widely used in various industries. In recent years, Raman spectroscopy (RS), as a spectroscopic technique, has gained much attention for measuring and monitoring emulsions. In this review, we explore the use of RS on emulsion structures and emulsification, important reactions that use emulsions such as emulsion polymerization, catalysis and cascading reactions, as well as various applications of emulsions. We explore how RS is used in emulsions, reactions and applications. RS is a powerful and versatile tool for studying emulsions, but there are also challenges in using RS to monitor emulsion processes, especially if they are rapid or volatile. We also explore these challenges and difficulties, as well as possible designs that can be used to overcome them.

Construction of whey protein gels prepared by three methods to stabilize high internal phase Pickering emulsions loaded with CoQ10 under different pH

The aim of this study was to investigate the effect of whey protein gel particles (WPGPs) prepared by heat-induced method, enzyme cross-linking method and calcium ion cross-linking method on the structural properties and intrinsic linkage of their stable high internal phase Pickering emulsions (HIPPEs) under different pH conditions. The effects of different pH and preparation methods on the internal interaction forces, particle size, ζ-potential, wettability and secondary structure of gels was investigated. The results indicated that the construction of HIPPEs system was successfully constructed at pH 3, 5 or 7. The WPGPs stabilized HIPPEs can maintain stable state at 4 °C for 28 days. Coenzyme Q10 (CoQ10) loaded with HIPPEs increased the bioavailability from 13.2% to 79.4%, which was demonstrated in in vitro digestion experiments.

Clove Essential Oil Pickering Emulsions Stabilized with Lactoferrin/Fucoidan Complexes: Stability and Rheological Properties

Although studies have shown that lactoferrin (LF) and fucoidan (FD) can be used to stabilize Pickering emulsions, there have been no studies on the stabilization of Pickering emulsions via the use of LF-FD complexes. In this study, different LF-FD complexes were obtained by adjusting the pH and heating the LF and FD mixture while using different mass ratios, and the properties of the LF-FD complexes were investigated. The results showed that the optimal conditions for preparing the LF-FD complexes were a mass ratio of 1:1 (LF to FD) and a pH of 3.2. Under these conditions, the LF-FD complexes not only had a uniform particle size of 133.27 ± 1.45 nm but also had good thermal stability (the thermal denaturation temperature was 110.3 °C) and wettability (the air-water contact angle was 63.9 ± 1.90°). The concentration of the LF-FD complexes and the ratio of the oil phase influenced the stability and rheological properties of the Pickering emulsion such that both can be adjusted to prepare a Pickering emulsion with good performance. This indicates that LF-FD complexes represent promising applications for Pickering emulsions with adjustable properties.

Food-Grade Oil-in-Water (O/W) Pickering Emulsions Stabilized by Agri-Food Byproduct Particles

In recent years, emulsions stabilized by solid particles (known as Pickering emulsions) have gained considerable attention due to their excellent stability and for being environmentally friendly compared to the emulsions stabilized by synthetic surfactants. In this context, edible Pickering stabilizers from agri-food byproducts have attracted much interest because of their noteworthy benefits, such as easy preparation, excellent biocompatibility, and unique interfacial properties. Consequently, different food-grade particles have been reported in recent publications with distinct raw materials and preparation methods. Moreover, emulsions stabilized by solid particles can be applied in a wide range of industrial fields, such as food, biomedicine, cosmetics, and fine chemical synthesis. Therefore, this review aims to provide a comprehensive overview of Pickering emulsions stabilized by a diverse range of edible solid particles, specifically agri-food byproducts, including legumes, oil seeds, and fruit byproducts. Moreover, this review summarizes some aspects related to the factors that influence the stabilization and physicochemical properties of Pickering emulsions. In addition, the current research trends in applications of edible Pickering emulsions are documented. Consequently, this review will detail the latest progress and new trends in the field of edible Pickering emulsions for readers.

Hydrophobically modified silica nanolaces-armored water-in-oil pickering emulsions with enhanced interfacial attachment energy

HYPOTHESIS

Anisotropic particles with a high aspect ratio led to favorable interfacial adhesion, thus enabling Pickering emulsion stabilization. Herein, we hypothesized that pearl necklace-shaped colloid particles would play a key role in stabilizing water-in-silicone oil (W/S) emulsions by taking advantage of their enhanced interfacial attachment energy.

EXPERIMENTS

We fabricated hydrophobically modified silica nanolaces (SiNLs) by depositing silica onto bacterial cellulose nanofibril templates and subsequently grafting alkyl chains with tuned amounts and chain lengths onto the nanograins comprising the SiNLs.

FINDINGS

The SiNLs, of which nanograin has the same dimension and surface chemistry as the silica nanospheres (SiNSs), showed more favorable wettability than SiNSs at the W/S interface, which was supported by the approximately 50 times higher attachment energy theoretically calculated using the hit-and-miss Monte Carlo method. The SiNLs with longer alkyl chains from C6 to C18 more effectively assembled at the W/S interface to produce a fibrillary interfacial membrane with a 10 times higher interfacial modulus, preventing water droplets from coalescing and improving the sedimentation stability and bulk viscoelasticity. These results demonstrate that the SiNLs acted as a promising colloidal surfactant for W/S Pickering emulsion stabilization, thereby allowing the exploration of diverse pharmaceutical and cosmetic formulations.

Construction of high internal phase Pickering emulsions using cold plasma modified soy protein isolate-proanthocyanidin complex

Protein-based high internal phase Pickering emulsions (HIPPEs) feature numerous multi-functionalities and widespread applications. However, the direct use of native proteins for the constructions of HIPPEs is limited since it is fragile under various conditions. Here, cold plasma was used to modify soy protein isolates (SPI) to improve their surficial properties. Meanwhile, proanthocyanidins (PA) were applied to interact with cold plasma-treated SPI to form complex. Furthermore, the well-prepared SPI-PA complex was used to construct novel HIPPEs. Results showed cold plasma treatment significantly improved the functionalities of SPI, which were confirmed by surface hydrophobicity (H₀ ＜ 500), sulfhydryl (SH) groups and spectral analysis. Further, the emulsification and oxidation resistance of cold plasma treated SPI were enhanced after forming complex with PA. Soybean oils can be stabilized by SPI-PA complexes to form HIPPEs with a lipid oxidation inhibition rate of ＞ 65%, creaming index (CI) ＞ 80%, excellent rheological properties and better stability compared with conventional emulsion systems. Overall, this SPI-PA complexes provides a unique approach to improve the emulsification and oxidation resistance to engineer HIPPEs with versatile applications.

Comparison of properties and application of starch nanoparticles optimized prepared from different crystalline starches

Starch nanoparticles (SNPs) were produced by nanoprecipitation combined with ultrasonication with the use of different starches (corn, potato and sago starch) and used to stabilize Pickering emulsions. The orthogonal experiment was used to optimize preparation conditions of gelatinization pretreatment duration of 30 min, ultrasonic power of 600 W, and ultrasonic time of 40 min. Compared with native starch, the SNPs were spherical in shape and displayed a V-type crystalline structure with low relative crystallinity and higher degree of double-helix. Compared with native starch-Pickering emulsion, the SNP-Pickering emulsion had a smaller droplet size, more uniform distribution, clearer oil/water interface, and higher static stability of droplets. The sago SNP-Pickering emulsion had the great gelatinous structure and emulsion stability. In addition, the SNP-Pickering emulsion had the better loading efficiency and controlled release performance of curcumin. Meanwhile, the bioavailability of curcumin in sago SNP-Pickering emulsion was highest.

Effects of ultrasound pretreatment on functional property, antioxidant activity, and digestibility of soy protein isolate nanofibrils

Nanofibrils, an effective method to modulate the functional properties of proteins, can be promoted by ultrasound pretreatment. This study investigated the effect of ultrasound pretreatment on the structure, functional property, antioxidant activity and digestibility of soy protein isolate (SPI) nanofibrils. The results showed that high amplitude ultrasound had a significant effect on structure of SPI nanofibrils. SPI nanofibrils pretreated by 80% amplitude ultrasound showed a blueshift of the amide II band in Fourier transform infrared spectroscopy (FTIR), resulted in more tryptophan residues being buried and increased the crystallinity. Low amplitude ultrasound (20%) pretreatment significantly improved the solubility, emulsifying activity index (EAI) and water absorption capacity (WAC) of SPI nanofibrils, but 80% amplitude ultrasound pretreatment of SPI nanofibrils reduced emulsifying stability index (ESI). High amplitude ultrasound (60% and 80%) pretreatment of SPI nanofibrils improved the foaming capacity and foaming stability and decreased denaturation temperature. DPPH radical scavenging activity of SPI nanofibrils were significantly improved by ultrasound pretreatment. 20% amplitude ultrasound pretreatment improved DPPH, ABTS radical scavenging activity and ferric reducing antioxidant power of SPI nanofibrils. The digestion rate of 80% amplitude ultrasound-pretreated nanofibrils were consistently higher, and SPI nanofibrils pretreated by ultrasound were more fragmented and shorter after simulating gastrointestinal digestion. This study would expand the application of food-grade protein nanofibrils in the food industry.

Nanofibrils of food-grade proteins: Formation mechanism, delivery systems, and application evaluation

Due to the high aspect ratio, appealing mechanical characteristics, and various adjustable functional groups on the surface proteins, food-grade protein nanofibrils have attracted great research interest in the field of food science. Fibrillation, known as a process of peptide self-assembly, is recognized as a common attribute for food-grade proteins. Converting food-grade proteins into nanofibrils is a promising strategy to broaden their functionality and applications, such as improvement of the properties of gelling and emulsifying, especially for constructing various delivery systems for bioactive compounds. Protein source and processing conditions have a great impact on the size, structure, and morphology of nanofibrils, resulting in extreme differences in functionality. With this feature, it is possible to engineer nanofibrils into four different delivery systems, including gels, microcapsules, emulsions, and complexes. Construction of nanofibril-based gels via multiple cross-linking methods can endow gels with special network structures to efficiently capture bioactive compounds and extra mechanical behavior. The adsorption behavior of nanofibrils at the interface is highly complex due to the influence of several intrinsic factors, which makes it challenging to form stabilized nanofibril-based emulsion systems. Based on electrostatic interactions, microcapsules and complexes prepared using nanofibrils and polysaccharides have combined functional properties, resulting in adjustable release behavior and higher encapsulation efficiency. The bioactive compounds delivery system based on nanofibrils is a potential solution to enhance their absorption in the gastrointestinal tract, improve their bioavailability, and deliver them to target organs. Although food-grade protein nanofibrils show unknown toxicity to humans, further research can contribute to broadening the application of nanofibrils in delivery systems.

Ultrasonic-assisted pH shift-induced interfacial remodeling for enhancing the emulsifying and foaming properties of perilla protein isolate

In order to expand the applications of plant protein in food formulations, enhancement of its functionalities is meaningful. Herein, the effects of ultrasonic (20 KHz, 400 W, 20 min)-assisted pH shift (pH 10 and 12) treatment on the structure, interfacial behaviors, as well as the emulsifying and foaming properties of perilla protein isolate (PPI) were investigated. Results showed that the solubility of PPI treated by ultrasonic-assisted pH shift (named UPPI-10/12) exceeded 90 %, which was at least 2 and 1.4 times that of untreated PPI and ultrasound-based PPI. Meanwhile, UPPI-10/12 possessed higher foamability (increasing by at least 1.2 times) and good emulsifying stability. Ultrasonic-assisted pH shift treatment decomposed large PPI aggregates into tiny particles, evident from the dynamic light scattering (DLS) and atomic force microscopy results. Besides, this approach induced a decrease in α-helix of PPI and an increase in β-sheet, which might result in the exposure of the hydrophobic group on the structural surface of PPI, thus leading to the increase of surface hydrophobicity. The smaller size and higher hydrophobicity endowed UPPI-10/12 faster adsorption rate, tighter interfacial structure, and higher elastic modulus at the air- and oil-water interfaces, evident from the cryo-SEM and interfacial dilatational rheological results. Thus, the emulsifying and foaming properties could evidently enhance. This study demonstrated that ultrasonic-assisted pH shift technique was a simple approach to effectively improve the functional performance of PPI.

Fibrous and Spherical Aggregates of Ovotransferrin as Stabilizers for Oleogel-Based Pickering Emulsions: Preparation, Characteristics and Curcumin Delivery

This study aimed to explore the effects and mechanisms of differently shaped aggregates of ovotransferrin (OVT) particles on oleogel-based Pickering emulsions (OPEs). Medium-chain triglyceride oil-based oleogels were constructed using beeswax, and their gel-sol melting temperatures were investigated. Atomic force microscopy confirmed that both OVT fibrils and OVT spheres were successfully prepared, and the three-phase contact angle measurements indicated that fibrous and spherical aggregates of OVT particles possessed great potential to stabilize the OPEs. Afterward, the oil-in-water OPEs were fabricated using oleogel as the oil phase and OVT fibrils/spheres as the emulsifiers. The results revealed that OPEs stabilized with OVT fibrils (FIB-OPEs) presented a higher degree of emulsification, smaller droplet size, better physical stability and stronger apparent viscosity compared with OPEs stabilized with OVT spheres (SPH-OPEs). The freeze–thaw stability test showed that the FIB-OPEs remained stable after three freeze–thaw cycles, while the SPH-OPEs could barely withstand one freeze–thaw cycle. An in vitro digestion study suggested that OVT fibrils conferred distinctly higher lipolysis (46.0%) and bioaccessibility (62.8%) of curcumin to OPEs.

A review on the physicochemical and biological applications of biosurfactants in biotechnology and pharmaceuticals

Biosurfactants are the chemical compounds that are obtained from various micro-organisms and possess the ability to decrease the interfacial tension between two similar or different phases. The importance of biosurfactants in cosmetics, pharmaceuticals, biotechnology, agriculture, food and oil industries has made them an interesting choice in various physico-chemical and biological applications. With the aim of representing different properties of biosurfactants, this review article is focused on emphasizing their applications in various industries summarizing their importance in each field. Along with this, the production of recently developed chemically and biologically important biosurfactants has been outlined. The advantages of biosurfactants over the chemical surfactants have also been discussed with emphasis on the latest findings and research performed worldwide. Moreover, the chemical and physical properties of different biosurfactants have been presented and different characterization techniques have been discussed. Overall, the review article covers the latest developments in biosurfactants along with their physico-chemical properties and applications in different fields, especially in pharmaceuticals and biotechnology.

The Potential Application of Pickering Multiple Emulsions in Food

Emulsions stabilized by adsorbed particles—Pickering particles (PPs) instead of surfactants and emulsifiers are called Pickering emulsions. Here, we review the possible uses of Pickering multiple emulsions (PMEs) in the food industry. Food-grade PMEs are very complex systems with high potential for application in food technology. They can be prepared by traditional two-step emulsification processes but also using complex techniques, e.g., microfluidic devices. Compared to those stabilized with an emulsifier, PMEs provide more benefits such as lower susceptibility to coalescence, possible encapsulation of functional compounds in PMEs or even PPs with controlled release, etc. Additionally, the PPs can be made from food-grade by-products. Naturally, w/o/w emulsions in the Pickering form can also provide benefits such as fat reduction by partial replacement of fat phase with internal water phase and encapsulation of sensitive compounds in the internal water phase. A possible advanced type of PMEs may be stabilized by Janus particles, which can change their physicochemical properties and control properties of the whole emulsion systems. These emulsions have big potential as biosensors. In this paper, recent advances in the application of PPs in food emulsions are highlighted with emphasis on the potential application in food-grade PMEs.

Iron delivery systems for controlled release of iron and enhancement of iron absorption and bioavailability

Iron deficiency is a global nutritional problem, and adding iron salts directly to food will have certain side effects on the human body. Therefore, there is growing interest in food-grade iron delivery systems. This review provides an overview of iron delivery systems, with emphasis on the controlled release of iron during gastrointestinal digestion, as well as the enhancement of iron absorption and bioavailability. Iron-bearing proteins are easily degraded by digestive enzymes and absorbed through receptor-mediated endocytosis. Instead, protein aggregates are slowly degraded in the stomach, which delays iron release and serves as a potential iron supplement. Amino acids, peptides and polysaccharides can bind iron through iron binding sites, but the formed compounds are prone to dissociation in the stomach. Moreover, peptides and polysaccharides can deliver iron by mediating the formation of ferric oxyhydroxide which is absorbed through endocytosis or bivalent transporter 1. In addition, liposomes are unstable during gastric digestion and iron is released in large quantities. Complexes formed by polysaccharides and proteins, and microcapsules formed by polysaccharides can delay the release of iron in the gastric environment and prolong iron release in the intestinal environment. This review is conducive to the development of iron functional ingredients and dietary supplements.