Ovalbumin-carboxymethylcellulose complex coacervates stabilized high internal phase emulsions: Comparison of the effects of pH and polysaccharide charge density

Emulsion co-stabilized with high methoxyl pectin and myofibrillar protein: Used to enhance the application in emulsified gel

This study evaluates the effects of high methoxyl pectin on the emulsion and gel properties of silver carp myofibrillar protein. An optimal concentration of pectin (3 mg/mL) enhances protein adsorption at the oil-water interface, forming a thermally induced oil-in-water emulsion gel with a denser and more robust fibrous network. The resulting gel exhibits a 3.8-fold increase in hardness and a 1.35-fold increase in water-holding capacity compared to the control. However, higher pectin concentrations (4-5 mg/mL) degrade emulsion-gel quality. By adjusting the ratio of myofibrillar protein to pectin, the emulsion's texture can transition from a fluid to a semi-solid state at room temperature, and the gel quality under heat treatment can be controlled. These findings offer a pathway to broaden the design and application of myofibrillar protein emulsions in multifunctional food products.

Effect of soybean phosphatidylethanolamine-tamarind gum Maillard conjugate on physicochemical stability of water-in-oil emulsions

Lipid oxidation hinders the development of water-in-oil (W/O) emulsions. This work aimed to determine the impact of soybean phosphatidylethanolamine (SP)/tamarind gum (TG) ratios on interface activity and anti-oxidant capacity of Maillard conjugates (MCs) in W/O emulsions. Results showed that grafting degree of MCs reached maximum with SP/TG ratio at 1:1 (43.5 %). Compared with SP and mixtures, interface activity (larger reduction of interfacial tension) and anti-oxidant capacity of MCs, especially with SP/TG = 1:1, were enhanced. The improvement of interface activity was owing to more stable adsorption at the interface caused by the increase of zeta potential and water contact angle as well as faster interface saturation benefited from broader steric network of TG moiety. The higher DPPH scavenging ability and ferric-reducing antioxidant power of MC were attributed to the combined effects of grafting degree, interface activity and molecule behavior of TG moiety. When the MC was added, the emulsion was observed smaller droplet size (1.3 μm), higher zeta potential (-73.5 mV) and lower contents of primary and secondary oxidation products (decreased by 70.9 % and 78.7 %, respectively). Hence, soybean phosphatidylethanolamine-tamarind gum-Maillard conjugate was effective to improve the physicochemical stability of W/O emulsions.

pH-regulated preparation and structural characterization of non-covalent complexes of soybean isolate proteins with different charged polysaccharides

Soybean protein isolate (SPI) exhibits limited functional properties in processing applications due to environmental stressors such as pH, salt ion, and temperature. The present study was devoted to exploring the non-covalent assembly of SPI with chitosan (CS), glucan (GL) and sodium alginate (SA) under different pH conditions. At a fixed mixing ratio (1:1), the phase behavior, protein solubility, and surface hydrophobicity (H0) of the resulting protein-polysaccharide complexes (PPCs) exhibited great differences due to the diversity of polysaccharide charge density and structure. Specifically, CS and SA primarily incorporated with SPI through electrostatic interactions, resulting in a pronounced enhancement of SPI solubility near the isoelectric point, with increases of 37.1 % and 51.6 %, respectively. In contrast, the combination of GL with SPI dominated by hydrophobic interactions and hydrogen bonds, yielding a similar protein solubility and H0 to SPI itself under different pH. Further analysis in charge density indicates that heat treatment promotes the electrostatic complexation of proteins with polysaccharides, whereas an increase in ionic strength inhibits the non-covalent assembly, and this effect was pronounced in the anionic polysaccharide system. In addition, the formation of electrostatic complexes exerted a positive effect on the stability of the emulsions, while the co-soluble systems tended to produce emulsion particles with smaller particle sizes. In summary, the charged polysaccharides showed great potential to modulate protein structure and enhance the stability of protein emulsions compared with the nonionic polysaccharides.

Synergistic stabilization of oil-in-water emulsion gels by pea protein isolate and cellulose nanocrystals: Effects of pH and application to 3D printing

In this study, pea protein isolate (PPI) and cellulose nanocrystals (CNC) were used to prepare oil-in-water emulsions, and the effects of pH and the oil content on the properties of the emulsions were investigated. The microstructural analysis revealed that PPI and CNC formed complexes by electrostatic attraction at pH 3.0 and 4.5, which assembled a dense interfacial layer around the oil droplets, improving emulsification performance. Moreover, the emulsions at these pH conditions exhibited semi-solid gel properties when the oil content was increased to 75 wt%, with better viscoelasticity compared to pH 8.0 and high thixotropic recovery rates in rheological experiments. Printing of flat stacked models with these high internal phase emulsions had a deformation rate of around 5 %, indicating desirable shear resistance and fidelity. These findings would offer valuable insights for developing fat substitutes and their application as edible inks for 3D printing.

Facile fabrication of stable O/W high internal phase emulsions with egg yolk fractions and hydroxypropyl distarch phosphate

High internal phase emulsions (HIPEs) can be used as suitable alternatives for saturated fatty acids. However, conventional approach for HIPEs preparation requires high energy-intensive production (e. g., ultrasonic, high-pressure homogenization) and tedious process. Herein, we report a facile approach to create stable O/W HIPEs using egg yolk (EY) fractions-hydroxypropyl distarch phosphate (HPDSP) complexes via one-step emulsification (500 rpm, 5 min). The addition of HPDSP could destroy the aggregated structure of EY, plasma (EYP) and granules (EYG). These disrupted EY, EYP and EYG partially absorb on the surface of HPDSP to form complexes via electrostatic and hydrophobic interactions. The initial interfacial tensions changed from 15.99 to 11.84 mN/m, from 14.98 to 10.98 mN/m, from 21.79 to 14.52 mN/m for EY, EYP and EYG because of the HPDSP addition, respectively. The addition of HPDSP increased the α-helix content and reduced the intermolecular β-sheet content of EYP/EYG. The presence of the EY/EYP/EYG-HPDSP complexes facilitated the formation of HIPEs with a solid-like structure and satisfactory storage/centrifugal stability. The HIPEs stabilized by EYP-HPDSP complexes showed smaller droplet sizes and viscoelasticity than those stabilized by EYG-HPDSP complexes. Conversely, EYP-HPDSP complexes stabilized HIPEs showed lower heat stability than EYG-HPDSP complexes stabilized HIPEs.

Surface modification of particles/nanoparticles to improve the stability of Pickering emulsions; a critical review

Pickering emulsions (PEs) are dispersions stabilized by solid particles, which are derived from various materials, both organic (proteins, polysaccharides, lipids) and inorganic (metals, silica, metal oxides). These colloidal particles play a critical role in ensuring the stability and functionality of PEs, making them highly valued across multiple industries due to their enhanced stability and lower toxicity compared to conventional emulsions. The stabilization mechanisms in PEs differ from those in emulsions stabilized by surfactants or biopolymers. The stability of PEs is influenced by intrinsic particle properties, such as wettability, size, shape, deformability, and charge, as well as external conditions like pH, salinity, and temperature. Some particles, especially organic ones, alone may not be effective stabilizers. For instance, many polysaccharides inherently lack surface activity, while most proteins have significant surface activity but often become unstable under environmental stresses, potentially leading to emulsion instability. The chemical composition and morphology of the particles can lead to varying properties, particularly wettability, which plays a vital role in their ability to adsorb at interfaces. As a result, surface modification emerges as an essential approach for improving the effectiveness of particles as stabilizers in PEs. This review presents the mechanisms that stabilize PEs, identifies factors influencing the stability of PEs, and discusses physical and chemical techniques for modifying particle surfaces. There has been a significant advance in understanding surface modification, employing both physical (non-covalent bonds) and chemical (covalent bonds) approaches. These insights are invaluable for optimizing PE formulations, broadening their application potential across various fields.

Delivery and controlled release abilities of chitosan/carboxymethylcellulose micropolyelectrolyte complexes (PECs) toward niacinamide (vitamin B3)

The administration of bioactive compounds presents challenges due to the numerous physiological barriers in the gastrointestinal tract. To deal with one of these challenges, chitosan (CHS)/carboxymethylcellulose (CMC) micropolyelectrolyte complexes (micro-PECs) were developed without the use of crosslinking agents to carry niacinamide, a model hydrophilic bioactive agent. A Box-Behnken design was used to study the effects of processing time (X1 = 60, 120 or 180 min), pH (X2 = 3, 4 or 5) and niacinamide concentration (X3 = 0.02, 0.04 and 0.06, g·L-1) on the encapsulation efficiency (Y1) and loading capacity (Y2) of niacinamide by CMC/CHS micro-PECs. The encapsulation efficiency (Y1) varied from 0.86 % to 80.78 %, whereas the loading capacity (Y2) varied between 0.03 % and 3.89 %. The digestibility of CMC/CHS micro-PECs containing niacinamide was evaluated in vitro via a static gastrointestinal model. Empirical models (Zero Order, First Order, Higuchi and Korsemeyer-Peppas) were fitted to the niacinamide release kinetics data. The zero-order model exhibited the best fit across all points (gastric and enteric digestion), with low zero-order constants (K0) ~ 0.002-0.003, indicating a regular and subdued release rate in all cases. These results highlight the applicability of CMC/CHS micro-PECs as an efficient, novel oral delivery system, surpassing conventional approaches by offering a sustained release and high encapsulation efficiency, without needing any additional chemical crosslinking agent for their obtention.

Effect of pH on the soybean whey protein-gum arabic emulsion delivery systems for curcumin: Emulsifying, stability, and digestive properties

A novel curcumin (CUR) delivery system was developed using soybean whey protein (SWP)-based emulsions, enhanced by pH-adjustment and gum arabic (GA) modification. Modulating electrostatic interactions between SWP and GA at oil/water interface, pH provides favorable charging conditions for stable distribution between droplets. GA facilitated the SWP form a stable interfacial layer that significantly enhanced the emulsifying properties and CUR encapsulation efficiency of the system at pH 6.0, which were 90.15 ± 0.67%, 870.53 ± 3.22 m2/g and 2157.62 ± 115.31%, respectively. Duncan's test revealed significant improvements in thermal, UV, oxidative, and storage stabilities of CUR (P < 0.05). At pH 6.0, GA effectively protected CUR by inhibiting SWP degradation during gastric digestion and promoting the release of CUR by decreasing steric hindrance with oil droplets during intestinal digestion, achieving the highest CUR bioaccessibility (69.12% ± 0.28%) based on Duncan's test. The SWP-GA-CUR emulsion delivery system would be a novel carrier for nutrients.

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.

Structure-property relationship of pea protein fibrils in stabilization of HIPEs and the encapsulation, protection, controlled release and oral delivery of carotenoids for alleviating intestinal inflammation

Increasing attentions are paid to high internal phase emulsions (HIPEs) due to their unique properties. In this study, pea protein-based fibrils were used as emulsifier to stabilize HIPEs. We demonstrated that the molecular assembly pathway and interfacial behavior of pea protein-based fibrils are affected by ionic strength. And the increased abundance of highly flexible worm-like nanofibrils facilitated their adsorption and packing on oil droplets, resulting in improved emulsion properties to stabilize the HIPEs with the internal phase volume fraction as high as 90%. Based on this, high loading content of carotenoids up to 0.05 wt% in the prepared HIPEs, protection of their stability against heating, UV and iron ions, and significantly increased bio-accessibilities of the carotenoids were realized. Animal studies using a mouse model of DSS-induced colitis revealed that carotenoid loaded HIPEs can alleviate the colon injury, by downregulating the expression of inflammatory cytokines, and promoting intestinal barrier function. This work will deepen the understanding of the formation of pea protein fibrils and provide a reference for the rational use of carotenoid loaded HIPEs in IBD management.

Composite formation of whey protein isolate and OSA starch for fabricating high internal phase emulsion: A comparative study at different pH and their application in biscuits

The composites formed by whey protein isolate (WPI) and octenyl succinate anhydride (OSA)-modified starch were characterized with a focus on the effect of pH, and their potential in fabricating high internal phase emulsions (HIPEs) as fat substitutes was evaluated. The particles obtained at pH 3.0, 6.0, 7.0, and 8.0 presented a nanosized distribution (122.04 ± 0.84 nm-163.24 ± 4.12 nm) while those prepared at pH 4.0 and 5.0 were remarkably larger. Results from the shielding agent reaction and Fourier transform infrared spectroscopy (FT-IR) showed that the interaction between WPI and OSA starch was mainly hydrophobic at pH 3.0-5.0, while there was a strong electrostatic repulsion at pH 6.0-8.0. A quartz crystal microbalance with dissipation (QCM-D) study showed that remarkably higher ΔD and lower Δf/n were observed at pH 3.0-5.0 after successive deposition of WPI and OSA starch, whereas slight changes were noted for those made at higher pH values. The WPI-OSA starch (W-O) composite-based HIPEs made at pH 3.0 and 6.0-8.0 were physically stable after long-term storage, thermal treatment, or centrifugation. Incorporation of HIPE into the biscuit formula yielded products with a desirable sensory quality.

Understanding the Impacts of Molecular and Macromolecular Crowding Agents on Protein-Polymer Complex Coacervates

Complex coacervation refers to the liquid-liquid phase separation (LLPS) process occurring between charged macromolecules. The study of complex coacervation is of great interest due to its implications in the formation of membraneless organelles (MLOs) in living cells. However, the impacts of the crowded intracellular environment on the behavior and interactions of biomolecules involved in MLO formation are not fully understood. To address this knowledge gap, we investigated the effects of crowding on a model protein-polymer complex coacervate system. Specifically, we examined the influence of sucrose as a molecular crowder and polyethylene glycol (PEG) as a macromolecular crowder. Our results reveal that the presence of crowders led to the formation of larger coacervate droplets that remained stable over a 25-day period. While sucrose had a minimal effect on the physical properties of the coacervates, PEG led to the formation of coacervates with distinct characteristics, including higher density, increased protein and polymer content, and a more compact internal structure. These differences in coacervate properties can be attributed to the effects of crowders on individual macromolecules, such as the conformation of model polymers, and nonspecific interactions among model protein molecules. Moreover, our results show that sucrose and PEG have different partition behaviors: sucrose was present in both the coacervate and dilute phases, while PEG was observed to be excluded from the coacervate phase. Collectively, our findings provide insights into the understanding of crowding effects on complex coacervation, shedding light on the formation and properties of coacervates in the context of MLOs.

Effect of Lactobacillus plantarum fermentation on the physicochemical properties and flavor of rice protein-carboxymethylcellulose complexes

BACKGROUND

Fermentation is known to enhance the nutritional profile and confer unique flavors to products. However, the resultant effects on stability and physicochemical properties remain unexplored.

RESULTS

This study aims to elucidate the influence of fermentation on the stability and organoleptic characteristics of a rice protein beverage stabilized by carboxymethyl cellulose (CMC). The findings revealed that the average aggregate size escalated from 507 to 870 nm, concurrently exhibiting a significant increase in surface potential. The aggregation enhancement was substantiated by evident morphological changes and confocal laser scanning microscopical (CLSM) observations. A negative correlation was discerned between the physical stability of the beverage and fermentation duration. Moreover, flavor analysis of the beverage post a 3 h fermentation period highlighted an increase in aromatic ester compounds, thereby intensifying the aroma.

CONCLUSION

The study corroborates that fermentation can detrimentally influence product stability while concurrently improving its flavor profile. By establishing a mix ratio of 10:1 for rice protein and CMC and forming a relatively stable system through electrostatic interaction at a pH of 5.4, a flavorful rice protein beverage can be derived post 3 h-fermentation process. These findings offer insights into the impact of varying fermentation durations on the stability and flavor of polysaccharide-based rice protein beverages. © 2023 Society of Chemical Industry.

Low Fatization of High-Fat Surimi-Based Products: Optimization of the Application of Protein Matrix Fat Substitution Methods

The low fatization of high-fat foods is a significant trend that will impact the future developments of food products. Consumers have regarded health attributes as a critical indicator for purchasing food. In this study, enzyme-modified soy protein isolate, sea fish collagen, and ovalbumin were used to prepare the composite fat substitute for the protein matrix. This matrix was applied to the traditional surimi-based product Nemipterus virgatus fish sausage to replace the exogenous fat, and a new type of low-fat fish sausage was developed. This change is expected to reduce the exogenous fat in the traditional fish sausage without reducing the flavor and sensory quality of the original product. The results showed that taking the sensory evaluation and gel strength value of the product as indicators, the optimal ratio of compound fat substitute (enzyme-modified soy protein isolate:sea fish collagen:ovalbumin) was 2:1:3 when using the orthogonal test method for the first time. In the next step, with compound fat substitutes, exogenous fats and transglutaminase as the main factors, single factor and response surface method were used to explore the best formula of new low-fat Nemipterus virgatus fish sausage. The results showed that the best gel strength and sensory evaluation scores were obtained when the compound fat substitute, TGase, and exogenous fat were 0.59 g, 0.245 g, and 8.03 g, respectively. The optimal formulation of the low-fat Nemipterus virgatus fish sausage was obtained as follows: surimi, 67.52%; complex fat substitute, 0.66%; TGase, 0.28%; fat, 9.04%; starch, 6.75%; sugar, 3.94%; salt, 2.25%; monosodium glutamate, 0.23%; I&G, 0.34%; and water, 9%. Compared with the traditional fish sausage, the content of exogenous fat in the new, low-fat Nemipterus virgatus fish sausage was reduced by 54.8%. Meanwhile, the sensory score of fish sausage was increased by 21.79%, maintaining its good flavor and sensory quality. This study provides an important reference value for developing new low-fat surimi-based products.

Soy protein isolate-citrus pectin-gallic acid ternary composite high internal phase Pickering emulsion for delivery of β-carotene: Physicochemical, structural and digestive properties

The structure properties, stability and β-carotene slow-release mechanism of soybean protein isolate-citrus pectin-gallic acid complex (SPI-CP-GA) stabilized high-internal phase Pickering emulsion (HIPPE) were investigated. The results showed that compared with the SPI-CP binary complex, the turbidity of the SPI-CP-GA ternary complex increased from 2.174 ± 0.001 to 3.027 ± 0.001, the surface wettability was increased, the infrared peaks was blue-shifted, changed from hydrophilic to hydrophobic, and the equilibrium interfacial tension of particles increased from 10.77 ± 0.02 mN/m to 13.46 ± 0.03 mN/m, the complex was more stable. When the GA was 2.0 mg/mL, the encapsulation efficiency of β-carotene was higher. With increased GA concentration and oil phase volume fraction (φ), the apparent viscosity and viscoelastic behavior of HIPPE performed well, forming a stable gel network structure. After 30 days of storage, there was no oil separation in the sample group with GA concentration of 2.0 mg/mL and φ = 0.7, and the stability was strong. After gastrointestinal digestion, the particle size of the HIPPE decreased from 13.51 ± 0.86 μm to 7.70 ± 0.68 μm, the free fatty acid (FFA) release rate was 22.03%, and the bioaccessibility of β-carotene was 6.67 ± 0.19%, and the sustained-release effect was obvious. These results indicated that the SPI-CP-GA ternary complex is a potential stabilizer for HIPPE, and providing theoretical guidance for the design of protein-polysaccharide-polyphenol stabilized HIPPE.

High internal phase Pickering emulsions stabilized by ε-poly-l-lysine grafted cellulose nanofiber for extrusion 3D printing

An effective method for preparing food-grade three-dimensional (3D) printing materials was the use of highly concentrated oil-in-water emulsions. This research reported 3D printable materials constructed from food-grade high internal phase Pickering emulsions (HIPPEs) that were stabilized by ε-poly-l-lysine grafted cellulose nanofiber (ε-PL-TOCNs). The ε-PL-TOCNs were prepared via ε-poly-l-lysine grafting of 2, 2, 6, 6-tetramethylpiperidine-N-oxyl (TEMPO)-oxidized cellulose (TOC) and the successive mechanical treatment. Subsequently, the chemical structure, microstructure and surface properties of ε-PL-TOCNs were characterized. The results showed that the prepared ε-PL-TOCNs had excellent dispersion performances, cationic properties brought by amino groups, and hydrophilic/hydrophobic functions of chain structure, which confirmed the feasibility of preparing HIPPEs. The HIPPEs with an internal phase volume fraction of 82 % were obtained at 0.8 wt% ε-PL-TOCNs concentration and pre-emulsification followed by continuous oil feeding. The HIPPEs' storage stability, morphology, and rheological behavior were further discussed. The ultra stable HIPPEs with apparent shear-thinning behavior and high solid viscoelasticity were successful produced, which was suitable for 3D printing. This work expanded the application of nanocellulose in emulsions field and provided a new thinking to prepare food-grade 3D printable materials and porous foam.

Quinoa protein Pickering emulsion: A promising cryoprotectant to enhance the freeze-thaw stability of fish myofibril gels

In this work, the effects of different QPE addition on the freeze-thaw (F-T) stability of fish myofibrillar protein (MP) gels were revealed. During freezing process, QPE decreased the freezing point of MP gels and shortened the time to pass through the maximum-ice-crystal-formation zone. The occurrence of thermal hysteresis effect led to the formation of small ice crystals and alleviated the damage to MP gel network. The incorporation of 7.5% QPE also reduced the free water amount to 19.23% and improved the water holding capacity of MP gels. Furthermore, the incorporation of QPE decreased the carbonyl content of MP gels after F-T cycles and delayed the protein oxidation. Meanwhile, QPE addition maintained the stability of the tertiary structure of MP gels via stabilizing the microenvironment of tyrosine and tryptophan. Overall, QPE shows the potential as a new cryoprotectant to improve the F-T stability of MP gel products.

Allergenicity, assembly and applications of ovalbumin in egg white: a review

Ovalbumin (OVA), the most abundant protein in egg whites, has been widely used in various industries. Currently, the structure of OVA has been clearly established, and the extraction of high-purified OVA has become feasible. However, the allergenicity of OVA is still a serious problem because it can cause severe allergic reactions and may even be life-threatening. The structure and allergenicity of the OVA can be altered by many processing methods. In this article, a detailed description on the structure and a comprehensive overview on the extraction protocols and the allergenicity of OVA was documented. Additionally, the information on assembly and potential applications of OVA was summarized and discussed in detail. Physical treatment, chemical modification, and microbial processing can be applied to alter the IgE-binding capacity of OVA by changing its structure and linear/sequential epitopes. Furthermore, research indicated that OVA could assemble with itself or other biomolecules into various forms (particles, fibers, gels, and nanosheets), which expanded its application in the food field. OVA also shows excellent application prospects, including food preservation, functional food ingredients and nutrient delivery. Therefore, OVA demonstrates significant investigation value as a food grade ingredient.

Novel Colloidal Food Ingredients: Protein Complexes and Conjugates

Food proteins, polysaccharides, and polyphenols are natural ingredients with different functional attributes. For instance, many proteins are good emulsifiers and gelling agents, many polysaccharides are good thickening and stabilizing agents, and many polyphenols are good antioxidants and antimicrobials. These three kinds of ingredients can be combined into protein, polysaccharide, and/or polyphenol conjugates or complexes using covalent or noncovalent interactions to create novel multifunctional colloidal ingredients with new or improved properties. In this review, the formation, functionality, and potential applications of protein conjugates and complexes are discussed. In particular, the utilization of these colloidal ingredients to stabilize emulsions, control lipid digestion, encapsulate bioactive ingredients, modify textures, and form films is highlighted. Finally, future research needs in this area are briefly proposed. The rational design of protein complexes and conjugates may lead to the development of new functional ingredients that can be used to create more nutritious, sustainable, and healthy foods.

Physicochemical and functional properties of capsaicin loaded cricket protein isolate and alginate complexes

As people become more aware of the health benefits of foods and their nutritional benefits for preventing diseases and promoting health, the demand for functional foods rich in proteins, fiber, and bioactives like capsaicin (CAP) is constantly rising. This study hypothesized that the electrostatic complexes developed by cricket protein isolate (CPI) and alginate (AL) could be utilized to encapsulate CAP, making it more water-soluble and protecting it at acidic pHs. Quantitative analysis revealed that CAP was efficiently encapsulated into the CPI-AL complexes with a maximum encapsulation efficiency of 91%, improving its aqueous solubility 45-fold. In vitro release tests showed that CAP was retained at acidic pHs (3.0 and 5.0) in CPI-AL complexes but released steadily at neutral pH (7.4), which will protect CAP in the stomach while enabling its release in the small intestine. Moreover, the antioxidant activity of CAP-CPI-AL complexes was superior to that of their individual bare equivalents. The complexes also demonstrated enhanced emulsifying capabilities and stability at acidic pHs (2.0-5.0) as the CPI fraction in the complexes increased. Our findings thus contribute to the growing body of knowledge that validates protein-polysaccharide complexation as a promising strategy for developing edible delivery systems.

Aggregation and Growth Mechanism of Ovalbumin and Sodium Carboxymethylcellulose Colloidal Particles under Thermal Induction

Ovalbumin (OVA)/sodium carboxymethylcellulose (CMC) colloidal particles were prepared with different compactness and morphologies by regulating the interaction between proteins and polysaccharides during heating. Electrostatic interactions between the amine groups of OVA (-NH₃⁺) and carboxyl groups of CMC (-COO^-) enhanced complex formation. The protein conformation change benefited the hydrophobic interaction between the particles. Proteins in colloidal particles were unfolded/folded under thermal induction to form aggregates having more β-sheet structures. When the OVA/CMC ratio was 1:2, the initially loosely connected OVA/CMC aggregation changed into a uniform sphere between 25 and 90 °C. The mass ratio of OVA to CMC within the final colloidal particle (90 °C) was about 1:1.4. The OVA/CMC particle stability was maintained with hydrogen bonding, hydrophobicity, and disulfide bond. When OVA levels were predominant, OVA and CMC developed an approximately hollow sphere. Moreover, the final colloidal particle composition showed the OVA-to-CMC ratio as 3:1 (w/w). OVA bound into colloidal particle pores to increase compactness. Moreover, OVA and CMC bound to the colloidal particle while the particle shrank, thereby increasing the compactness of colloidal particles. There was a significant decrease in ABTS^•+ scavenging activity of curcumin compared with that of the particles with a ratio of 1:2. Thus, the rational adjustment of the structure of colloidal particles could effectively enhance their functional characteristics, providing a new way for the controlled release of the active ingredients.

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.

Research advance of non-thermal processing technologies on ovalbumin properties: The gelation, foaming, emulsification, allergenicity, immunoregulation and its delivery system application

Ovalbumin (OVA) is the most abundant protein in egg white, with excellent functional properties (e.g., gelling, foaming, emulsifying properties). Nevertheless, OVA has strong allergenicity, which is usually mediated by specific IgE thus results in gut microbiota dysbiosis and causes atopic dermatitis, asthma, and other inflammation actions. Processing technologies and the interactions with other active ingredients can influence the functional properties and allergic epitopes of OVA. This review focuses on the non-thermal processing technologies effects on the functional properties and allergenicity of OVA. Moreover, the research advance about immunomodulatory mechanisms of OVA-mediated food allergy and the role of gut microbiota in OVA allergy was summarized. Finally, the interactions between OVA and active ingredients (such as polyphenols and polysaccharides) and OVA-based delivery systems construction are summarized. Compared with traditional thermal processing technologies, novel non-thermal processing techniques have less damage to OVA nutritional value, which also improve OVA properties. OVA can interact with various active ingredients by covalent and non-covalent interactions during processing, which can alter the structure or allergic epitopes to affect OVA/active components properties. The interactions can promote OVA-based delivery systems construction, such as emulsions, hydrogels, microencapsulation, nanoparticles to encapsulate bioactive components and monitor freshness for improving foods quality and safety.

Preparation of a biobased polyelectrolyte complex from chitosan and sodium carboxymethyl cellulose and its antibacterial characteristics

Using chitosan (CTS) and sodium carboxymethyl cellulose (CMCNa) as raw biobased materials, polyelectrolyte complex (PEC), which is the product of strong electrostatic interaction between two bio-based polyelectrolytes with opposite charges, was attempted to prepare. To enlarge the reactive contact area between CTS and CMCNa, the crosslinked vacuolar structure of PEC was prepared without addition of cross-linked agent. The preparation conditions had a significant impact on the yield of PEC and the bibulous rate of PEC. When pH, mass ratio of CMC-Na-to-CTS, stirring speed and reaction system temperature were 5, 1:2 [(1 wt% CMCNa, 2 wt% CTS), CMC-Na:CTS = 1:1 (v/v)], 800 rpm, 2 min and 25 °C, the yield of PEC reached 71.2 %. The prepared PEC was characterized by XRD and FT-IR. Afterwards, the antibacterial performance of PEC was examined. The prepared PEC had certain bacteriostatic effect on gram-positive and gram-negative bacteria. The bacteriostasis ratios of PEC against Escherichia coli and Staphylococcus aureus were 18.7 % and 31.3 %, respectively. By controlling the combination parameters of the preparation system, an effective strategy was successfully developed for preparation of biobased PEC with bacteriostatic and crosslinked vacuolar structure through simple physical blending without the application of additional crosslinker.

Formation, stability and the application of Pickering emulsions stabilized with OSA starch/chitosan complexes

We demonstrated the formation, structure and stability of Pickering emulsions stabilized by octenyl succinic anhydride starch (OSA-S)/chitosan (CS) complexes and explored their potential as templates for porous materials. Sufficient oil fraction (Φ > 50 %) was decisive for stable emulsions, whereas the complex concentration (c) significantly affected the gel network of emulsions. An increase in Φ or c led to tighter droplet arrangement and enhanced network, which improved the self-supporting characteristics and the stability of emulsions. The stacking of OSA-S/CS complexes at the oil-water interface influenced the emulsion properties, forming typical microstructure with small droplets embedded in interstices of large droplets, and bridging flocculation occurred. Porous materials prepared using emulsions (Φ > 75 %) as templates exhibited semi-open structures with pore size and network varying with different Φ or c. There was no structure collapse due to the interconnectivity of complexes. Our work provides comprehensive information on OSA-S/CS complex-stabilized Pickering emulsions.

Ultra-stable high internal phase emulsions stabilized by protein-anionic polysaccharide Maillard conjugates

This paper reports the production of O/W high internal phase emulsions (HIPEs) using protein-anionic polysaccharide Maillard conjugates. First, Maillard conjugates were prepared from soy protein isolate (SPI) or sodium caseinate (SC) proteins and Alyssum homolocarpum seed gum (AHSG) or kappa-carrageenan (kC) polysaccharides. The conjugation process was confirmed and monitored by UV spectrophotometry, Fourier transform infrared, circular dichroism, fluorescence spectroscopies, and differential scanning calorimetry. Under the optimized reaction conditions, SC-AHSG conjugates exhibited the highest glycation degree and emulsifying properties. Next, HIPEs were made using the optimized conjugates, and their microstructure, droplet size, and physical stability were evaluated. The emulsion stabilized by SC-AHSG conjugate had the lowest mean droplet size (363.07 ± 34.56 nm), orderly-packed oil droplets with monomodal distribution, the highest zeta potential (-27.70 ± 0.70 mV), high storage stability (no creaming or oil-off) and was ultra-stable against environmental stresses. Results of this research are helpful for development of emulsion-based foods with novel functionality.

Fabrication and digestive characteristics of high internal phase Pickering emulsions stabilized by ovalbumin-pectin complexes for improving the stability and bioaccessibility of curcumin

In this study, ovalbumin (OVA) interacted with pectin (PE) to form soluble electrostatic complexes to improve the functional properties of high internal phase Pickering emulsions (HIPEs) under extreme conditions. The results showed that the stability of the OVA-PE soluble complexes-stabilized HIPEs was significantly better than that of the free OVA-stabilized HIPEs and was modulated by the biopolymer ratio. In particular, the complexes at an OVA:PE ratio of 1:1 (C-1:1) may form particulates with a core-shell structure by a flocculation mechanism. The C-1:1-stabilized HIPEs had the smallest oil droplet size (11.34 ± 1.14 μm) and the best resistance to extreme environmental stresses due to their strong, rigid structure and dense interfacial architecture. The in vitro digestion results showed that the bioaccessibility (from 18.3% ± 0.5% to 38.8% ± 4.8%) of curcumin improved with increasing PE content. Our work is helpful in understanding OVA-PE complexes as stabilizers for HIPEs and their potential applications in food delivery systems.

Improvement of O/W emulsion performance by adjusting the interaction between gelatin and bacterial cellulose nanofibrils

This study was designed to improve the stability of medium internal phase emulsion by adjusting the electrostatic interaction between gelatin (GLT) and TEMPO-oxidized bacterial cellulose nanofibrils (TOBC). The influences of polysaccharide-protein ratio (1:10, 1:5, and 1:2.5) and pH (3.0, 4.7, 7.0, and 11.0) on the emulsion properties were investigated. The droplet size of TOBC/GLT-stabilized emulsion was increased with the TOBC proportion increasing at pH 3.0-11.0. Additionally, emulsion had a larger droplet size at pH 4.7 (the electrical equivalence point pH of mixtures). However, the addition of TOBC significantly improved the emulsion stability. The emulsions prepared with TOBC/GLT mixtures (mixing ratio of 1:2.5) at pH 3.0-7.0 were stable without creaming during the storage. It was because the formation of nanofibrils network impeded the droplet mobility, and the emulsion viscosity and viscoelastic modulus were increased with the addition of TOBC. These findings were meaningful to modulate the physical properties of emulsions.

High internal phase Pickering emulsions stabilized by co-assembled rice proteins and carboxymethyl cellulose for food-grade 3D printing

In this study, high internal phase Pickering emulsions (HIPPEs) stabilized by protein-polysaccharide complexes were used as inks for food-grade three-dimensional printing (3DP). The complexes (RCs) structured by synergistic interactions between rice proteins (RPs) and carboxymethyl cellulose (CMC) displayed outstanding biphasic wettability with excellent ability to reduce the oil/water interfacial tension. The interfacial structures formed by RCs provided a steric barrier and sufficient electrostatic repulsion, preventing droplet coalescence against heating treatment as well as long-term storage. Moreover, the rheological behaviors of the HIPPEs can be tuned by the substitution degree (DS) of CMC for tailorable hydrophobic/hydrophilic properties of RCs, allowing their controllable injectability and printability during 3DP. The HIPPEs stabilized by RCs with a DS 1.2 showed the most favorable printing resolution, hardness, adhesiveness, and chewiness. Associating the hydrophobic RPs with hydrophilic CMC, our study enabled on-demand amphiphilicity of RCs for effective stabilization of HIPPEs that can be manipulated for 3DP.

Protection of menhaden oil from oxidation in Pickering emulsion-based delivery systems with α-lactalbumin-chitosan colloidal nanoparticle

In this study, α-lactalbumin-chitosan (ALA-CHI) colloidal nanoparticles were spontaneously formed mainly through electrostatic interactions for stabilizing Pickering emulsion loaded with health-beneficial but unstable menhaden oil. The oxidative stability of menhaden oil was supposed to be significantly enhanced with Pickering emulsion-based delivery systems with ALA-CHI colloidal particles. The film of ALA-CHI colloidal nanoparticles had higher surface hydrophobicity than ALA at pH 5.0, and 6.5. A near-neutral wettability (89.6°) of ALA-CHI nanoparticles was observed at pH 5.0. Stable Pickering emulsions (60% menhaden oil fraction, w/w) were successfully fabricated with only 0.12% (w/w) of ALA-CHI nanoparticles. Pickering emulsions exhibited superior storage, heat, and centrifugation stability. The formation of gel-like structures was confirmed by rheological results. The viscosity and storage modulus in the frequency range of 0.1 to 10 Hz with a 1.0% strain exhibited remarkable increases with increasing colloidal particle concentration or oil fraction. Increasing oil fractions from 20% to 60% (w/w) or colloidal particle concentrations 0.12% to 2.40% (w/w) can pronouncedly facilitate the inhibition of lipid oxidation, as confirmed by detecting the formation of primary and secondary oxidation products.

Self-Assembled Micellar Nanoparticles by Enzymatic Hydrolysis of High-Density Lipoprotein for the Formation and Stability of High Internal Phase Emulsions

In this study, the influence of pH on the conformational state of EHT, which was obtained from the enzymatic hydrolysis of trypsin, and the stabilizing properties of high internal phase emulsions have been demonstrated. Critical micelle concentration and transmission electron microscopy results exhibited the formation of micellar nanoparticles with mean diameters ranging from 108 to 1359.5 nm. The results of solubility, surface hydrophobicity, and conformations indicated that EHT tended to act as particulate emulsifiers at pH 3, 5, and 7, while at alkaline pH, it was more like a polymeric emulsifier, which could be proven by confocal laser scanning microscopy. The EHT at pH 7 exhibited better stabilizing properties than those at pH 9 and 11 as influenced by storage, temperature, and ionic strength. These findings might be of great importance for broadening the range of sustainable applications of amphiphilic peptides in foods and pharmaceuticals.