Effect of pH, ionic strength, chitosan deacetylation on the stability and rheological properties of O/W emulsions formulated with chitosan/casein complexes

Properties regulation and mechanism on ferritin/chitooligosaccharide dual-compartmental emulsions and its application for co-encapsulation of curcumin and quercetin bioactive compounds

Dual-compartmental emulsions, containing multiple chambers, possess great advantages in co-encapsulation of different cargoes. Herein, we reported a stable dual-compartmental emulsion by regulating the ratio of Marsupenaeus japonicus ferritin (MF) and chitooligosaccharide (COS), enabling efficient co-encapsulation of different compounds. The adsorption behavior of MF/COS complex over droplet interface varied at different ratios, thereby exerting an influence on the emulsion properties. Remarkably, emulsions stabilized by MF/COS complex at a ratio of 2:1 exhibited superior stability, as evidenced by no significant creaming or demulsification during storage or heat treatment. The mechanism is that MF/COS2:1 complex can enhance the formation of thicker interfacial layer and dense continuous phase network structure. Additionally, curcumin and quercetin can be co-encapsulated into the emulsions and their retention rates were significantly improved than those in oils, implying the potential of the resulting dual-compartmental emulsions in co-encapsulation and delivery of bioactive compounds.

Interfacial multilayer self-assembly of protein and polysaccharides: Ultrasonic regulation, stability and application in delivery lutein

In this study, the layer-by-layer adsorption behavior of sodium caseinate, pectin, and chitosan on the oil-water interface was illustrated using multi-frequency ultrasound. We investigated the impact of ultrasound on various factors, such as particle size, zeta potential, and interfacial protein/polysaccharide concentration. It was observed that ultrasound has significantly decreased droplet size and increased the surface area at the interface, hence promoting the adsorption of protein/polysaccharide. In the sonicated multilayer emulsion, the concentrations of interface proteins, pectin, and chitosan increased to 84.82 %, 90.49 %, and 83.31 %, respectively. The findings of the study indicated that the application of ultrasonic treatment had a significant impact on the emulsion's surface charge and the prevention of droplet aggregation. As a result, the stability of the emulsion system, including its resistance to salt, temperature, and storage conditions, has been significantly improved. Moreover, the emulsion showed an increase in the retention rate of lutein by 21.88 % after a high-temperature water bath and by 19.35 % after UV irradiation. Certainly, the multilayer emulsion treated with ultrasound demonstrated a superior and prolonged releasing behavior. These findings demonstrated the suitability of the ultrasound treatment for the preparation of emulsions to deliver bioactive compounds.

Influences of carboxymethyl chitosan upon stabilization and gelation of O/W Pickering emulsions in the presence of inorganic salts

The objective of this study was to investigate the effects of carboxymethyl chitosan (CMCS) on the stabilization and gelation of oil-in-water (O/W) Pickering emulsions (PEs) with polyphenol-amino acid particles in the presence of inorganic salts. The results revealed that the CMCS-induced depletion interactions contributed to improving the emulsification ability and interfacial adsorption efficiency of polyphenol-amino acid particles as well as constructing the network structures in the continuous phase. These relevant changes collectively resulted in elevating stability, viscosity and moduli of PEs. The additional effects of different inorganic salts with varying additions were further investigated, and the addition-dependent phenomena were observed. At low additions of inorganic salts, the occurrence of the chelation of inorganic salts with CMCS consolidated the constructed network structure, favorable to the gelation of PEs. With increasing additions, this chelation effect became stronger which compromised the CMCS-induced depletion, gradually leading to destabilization of PEs. In terms of ion species, the more pronounced effect on emulsion stability was achieved with calcium ions than with potassium and iron ions. This study expects to provide a new perspective on the extending application of cationic CMCS for improving the stability of O/W PEs in the food industry.

Quality Characteristics of Vegan Mayonnaise Produced Using Supercritical Carbon Dioxide-Processed Defatted Soybean Flour

Emulsifiers, like egg yolk (EY), are necessary for the formation of mayonnaise, which is an oil-in-water type of colloid. This study aimed to assess the potential of defatted soybean powder treated with supercritical carbon dioxide (DSF) to enhance the quality of plant-based mayonnaise as plant-based alternatives gain popularity. This study involved the production of DSF and the comparison of its quality attributes to those of mayonnaise made with varying amounts of control soy flour (CSF), DSF, and EY. It was found that mayonnaise made with an increased quantity of DSF showed better emulsion stability, viscosity, and a smaller, more uniform particle size when compared with CSF mayonnaise. Additionally, DSF mayonnaise was generally rated higher in sensory evaluation. The addition of approximately 2% DSF positively influenced the emulsion and sensory properties of the vegan mayonnaise, indicating that DSF is a promising plant-based alternative emulsifier for the replacement of animal ingredients.

Effect of polysaccharide concentration on heat-induced Tremella fuciformis polysaccharide-soy protein isolation gels: Gel properties and interactions

The formation of a single soybean protein isolate (SPI) gel is limited by the processing conditions, and has the disadvantages of poor gel property, and it is usually necessary to add other biomacromolecules to improve its property. In this study, we investigated the effects of polysaccharide concentration on gel properties and interaction mechanisms of Tremella fuciformis polysaccharide (TFP)-SPI complexes. It was found that (1) the rheological properties, texture properties, water-holding properties, and thermal stability of TFP-SPI composite gels were improved with the addition of TFP (0.25-2.0 %, w/v) in a concentration-dependent manner; (2) hydrogen bond, the electrostatic interaction, hydrophobic interaction, and disulfide bond in the gel system increased with the increase of TFP concentration; (3) the electrostatic and hydrophobic interactions played an important role in the formation of the TFP-SPI composite gel while hydrogen bond formation was the least contributor to the binary composite gel network. Overall, TFP is not only a critical health food but also a promising structural component for improving the gel properties of SPI.

Layer-by-layer coated probiotics with chitosan and liposomes demonstrate improved stability and antioxidant properties in vitro

Probiotics are of increasing interest for their potential health benefits, but their survival and adhesion in the harsh gastrointestinal environment remain a concern. This study explored a single-cell encapsulation technique to enhance probiotic survival and adhesion in the gastrointestinal tract. We encapsulated probiotics in curcumin-loaded liposomes, further coated them with polymers using layer-by-layer techniques. The coated probiotics were evaluated for survival in simulated gastrointestinal conditions, adhesion to colonic mucus, and scavenging of reactive oxygen species (ROS). The results showed that multi-layer encapsulation increased probiotic size at the nanoscale, enhancing their survival in simulated gastrointestinal conditions. Upon reaching the colon, the shedding of the coating coincided with probiotic proliferation. Additionally, the coated probiotics exhibited increased adhesion to colonic mucus. Moreover, the coating acted as a protective barrier for effectively scavenging reactive oxygen radicals, ensuring probiotic survival in inflammatory environments. This study combines the synergistic effects of probiotics and curcumin, underscoring the promise of single-cell encapsulation techniques in improving the efficacy of probiotics for addressing colitis-related diseases.

Effects of limited enzymatic hydrolysis and polysaccharide addition on the physicochemical properties of emulsions stabilized with duck myofibrillar protein under low-salt conditions

This study aimed to investigate the role of hydrolysis and guar gum (GG) participation on the emulsification of the duck myofibrillar protein (MP) and the related stability of oil-in-water emulsion in low-salt condition. Emulsions were prepared using one of each or both treatments, and that prepared with trypsin hydrolysis and GG (T-GG) exhibited the highest stability. FTIR analysis confirmed the hydrogen bond interactions between the system components. T-GG treatment improved emulsion properties and decreased oil droplet size. Moreover, CLSM indicated that aggregation of T-GG oil droplets was prevented. Physical stability was assessed such as Turbiscan stability index, creaming index, and rheological properties. The adsorbed percentage for T-GG was the lowest. However, interfacial tension, droplet size, stability, and peroxide value analyses indicated that a denser interfacial membrane structure is formed with T-GG. Thus, T-GG treatment could be applied in the food industry, such as in nutrient delivery systems and fat mimetics.

Noncovalent interactions between biomolecules facilitated their application in food emulsions' construction: A review

The use of biomolecules, such as proteins, polysaccharides, saponins, and phospholipids, instead of synthetic emulsifiers in food emulsion creation has generated significant interest among food scientists due to their advantages of being nontoxic, harmless, edible, and biocompatible. However, using a single biomolecule may not always meet practical needs for food emulsion applications. Therefore, biomolecules often require modification to achieve ideal interfacial properties. Among them, noncovalent interactions between biomolecules represent a promising physical modification method to modulate their interfacial properties without causing the health risks associated with forming new chemical bonds. Electrostatic interactions, hydrophobic interactions, and hydrogen bonding are examples of noncovalent interactions that facilitate biomolecules' effective applications in food emulsions. These interactions positively impact the physical stability, oxidative stability, digestibility, delivery characteristics, response sensitivity, and printability of biomolecule-based food emulsions. Nevertheless, using noncovalent interactions between biomolecules to facilitate their application in food emulsions still has limitations that need further improvement. This review introduced common biomolecule emulsifiers, the promotion effect of noncovalent interactions between biomolecules on the construction of emulsions with different biomolecules, their positive impact on the performance of emulsions, as well as their limitations and prospects in the construction of biomolecule-based emulsions. In conclusion, the future design and development of food emulsions will increasingly rely on noncovalent interactions between biomolecules. However, further improvements are necessary to fully exploit these interactions for constructing biomolecule-based emulsions.

Effect of polysaccharides on conformational changes and functional properties of protein-polyphenol binary complexes: A comparative study

This study aimed to investigate the effect of different polysaccharides on the binding behavior and functional properties of soybean protein isolate (SPI)-quercetin (Que) complex. The binding behavior was assessed using multi-spectral technique with the Stern-Volmer equation, which confirmed the presence of static fluorescence quenching in Que and SPI. The addition of sodium alginate (SA) resulted in a reduction of the binding affinity between SPI and Que, while dextran (DX) exhibited some promoting effect. A slight blue shift was observed in amide I and amide II bands, indicating the presence of hydrophobic and electrostatic interactions. Circular dichroism spectra revealed the ordered structures transformed into a more disordered state when polysaccharides were added, leading to an increase in random coils (SA: 18.5 %, DX: 15.4 %). Docking and dynamic simulations demonstrated that SA displayed greater stability within the hydrophobic compartments of SPI than DX, increased rigidity and stability of the SPI structure in SPI-Que-SA complexes. Electrostatic forces played a significant role between SPI and SA, while van der Waals forces were the main driving forces in SPI-DX complexes. Overall, the introduction of SA led to a looser and stable structure of SPI-Que complexes, resulting in an improvement of their emulsifying, foaming, and antioxidant properties.

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

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

Use of sodium alginate coatings to improve bioavailability of liposomes containing DPP-IV inhibitory collagen peptides

Sodium alginate (SA) was used to coat liposomes containing DPP-IV inhibitory collagen peptides to improve their stability and in vitro absorption for intra-oral delivery. The liposome structure as well as entrapment efficiency and DPP-IV inhibitory activity was characterized. The liposome stability was determined by measuring in vitro release rates and their gastrointestinal stability. Transcellular permeability of liposomes was further tested to characterize their permeability in small intestinal epithelial cells. The results showed that the 0.3% SA coating increased the diameter (166.7 nm to 249.9 nm), absolute value of zeta potential (30.2 mV to 40.1 mV) and entrapment efficiency (61.52% to 70.99%) of liposomes. The SA-coated liposomes containing collagen peptides showed enhanced storage stability within one month, gastrointestinal stability increased by 50% in bioavailability, transcellular permeability increased by 18% in transmission percentage, and in vitro release rates reduced by 34%, compared to uncoated liposomes. SA coating liposomes are promising carriers for transporting hydrophilic molecules, may be beneficial for improving nutrient absorption and can protect bioactive compounds from being inactivated in the gastrointestinal tract.

The physicochemical properties and stability of myofibrillar protein oil-in-water emulsions as affected by the structure of sugar

Different sugars (glucose, GL; fructose, FR; hyaluronic acid, HA; cellulose, CE) were added to a myofibrillar protein (MP) emulsion (MP: 1.2 w/v%, sugar: 0.1% w/v) to study the effect of sugar structure on the physicochemical properties and stability of the MP emulsions. The emulsifying properties of MP-HA were significantly (P < 0.05) higher than those of the other groups. The monosaccharide (GL/FR) exerted negligible effects on the emulsifying performance of the MP emulsions. The ζ-potential and particle size implied that HA introduced stronger negative charges, significantly reducing the final particle size (190-396 nm). Rheological examinations indicated that the introduction of polysaccharides considerably increased the viscosity and network entanglement; confocal laser scanning microscopy and creaming index revealed that MP-HA was stable during storage, whereas MP-GL/FR/CE exhibited severe delamination after long-term storage. HA, a heteropolysaccharide, is most suitable for improving MP emulsion quality.

Pickering emulsions stabilized with a spirulina protein-chitosan complex for astaxanthin delivery

Astaxanthin (AXT) is a lipid-soluble carotenoid with good anti-oxidation, hepatic steatosis reduction, anti-inflammation, and intestinal microbiota regulation ability, whose poor stability and pH vulnerability limit its bioavailability. Spirulina protein (SP) derived from spirulina has good emulsifying ability with potential application in nutraceuticals, medicines, and cosmetics. In this study, Pickering emulsions were prepared using a SP-chitosan (CS) complex as an emulsifier. The particle size, zeta potential, and three-phase contact angle of the SP-CS complex with different SP to CS ratios were investigated. A mass ratio of 1 : 2.5 SP-CS complex showed a good emulsifying ability in preparing Pickering emulsion. A higher storage modulus and viscoelasticity were observed with higher SP-CS complex concentrations and oil fractions. The SP-CS Pickering emulsion significantly improved the stability of AXT in different environments. The lipid release rate and AXT bioavailability after digestion of 3 wt% SP-CS complex-stabilized Pickering emulsion reached 70.54 ± 1.59% and 36.60 ± 3.44%, respectively. The results indicated that the SP-CS complex could act as a Pickering emulsion stabilizer and had the potential to deliver protective hydrophobic AXT.

Transglutaminase-Catalyzed Glycosylation Improved Physicochemical and Functional Properties of Lentinus edodes Protein Fraction

Lentinula edodes has high nutritional value and abundant protein. In order to develop and utilize edible mushroom protein, this study was designed to investigate the effects of TGase-catalyzed glycosylation and cross-linking on the physicochemical and functional properties of Lentinus edodes protein fraction. The results showed that within a certain time, glycosylation and TGase-catalyzed glycosylation decreased the total sulfydryl, free sulfydryl, disulfide bond, surface hydrophobicity, β-fold and α-helix, but increased the fluorescence intensity, random coil, β-turn, particle size and thermal stability. The apparent viscosity and the shear stress of the protein with an increase in shear rate were increased, indicating that TGase-catalyzed glycosylation promoted the generation of cross-linked polymers. In addition, the TGase-catalyzed glycosylated proteins showed a compact texture structure similar to the glycosylated proteins at the beginning, indicating that they formed a stable three-dimensional network structure. The flaky structure of proteins became more and more obvious with time. Moreover, the solubility, emulsification, stability and oil-holding capacity of enzymatic glycosylated Lentinus edodes protein fraction were significantly improved because of the proper TGase effects of glycosylation grafting and cross-linking. These results showed that glycosylation and TGase-catalyzed glycosylation could improve the processing characteristics of the Lentinula edodes protein fraction to varying degrees.

Effect of konjac oligo-glucomannan on emulsifying properties of myofibrillar protein

BACKGROUND

The high viscosity of konjac glumannan (KGM) limits its application in meat processing. In this work, the effects of konjac oligo-glucomannan (KOG), as a derivative of KGM, on the emulsifying properties of myofibrillar protein (MP) and the related mechanism were investigated.

RESULTS

It was found that the addition of KOG had no significant effect on the secondary structure of MP, but altered the tertiary conformation of MP, resulting in exposure of tyrosine residues to polar microenvironments and decreased intrinsic fluorescence intensity. In addition, the addition of KOG increased the emulsifying activity of MP, resulting in decreased particle size and improved physical stability of the emulsion. The emulsifying activity of MP reached the maximum value when 1.0 wt% KOG was added. Moreover, the interfacial tension and interfacially adsorbed protein content of MP/KOG emulsions decreased with the increase in KOG concentration.

CONCLUSION

These findings demonstrated that KOG mainly interacted with MP and changed the amphipathy of the KOG-MP at the oil-water interface, forming a stable interface film to improve the emulsifying properties of MP. © 2023 Society of Chemical Industry.

Recent developments in improving the emulsifying properties of chitosan

Chitosan is one of the valuable products obtained from crustacean waste. The unique characteristics of chitosan (antimicrobial, antioxidant, anticancer, and anti-inflammatory) have increased its application in various sectors. Besides unique biological properties, chitosan or chitosan-based compounds can stabilize emulsions. Nevertheless, studies have shown that chitosan cannot be used as an efficient stabilizer because of its high hydrophilicity. Hence, this review aims to provide an overview of recent studies dealing with improving the emulsifying properties of chitosan. In general, two different approaches have been reported to improve the emulsifying properties of chitosan. The first approach tries to improve the stabilization property of chitosan by modifying its structure. The second one uses compounds such as polysaccharides, proteins, surfactants, essential oils, and polyphenols with more wettability and emulsifying properties than chitosan's particles in combination with chitosan to create complex particles. The tendency to use chitosan-based particles to stabilize Pickering emulsions has recently increased. For this reason, more studies have been conducted in recent years to improve the stabilizing properties of chitosan-based particles, especially using the electrostatic interaction method. In the electrostatic interaction method, numerous research has been conducted on using proteins and polysaccharides to increase the stabilizing property of chitosan.

Food emulsifier based on the interaction of casein and butyrylated dextrin for improving stability and emulsifying properties

Green hydrophobically modified butyrylated dextrin (BD) was used to modulate casein (CN). The CN/BD complex nanoparticles were formed at different CN-to-BD mass ratios based on a pH-driven technology. The interaction force, stability, and emulsifying properties of complex nanoparticles were investigated. The nanoparticles had a negative charge and a small particle size (160.03, 152.6, 155.9, 206.13, and 231.67 nm) as well as excellent thermal stability and environmental stability (pH 4.5, 5.5, 6.6, 7.5, 8.5, and 9.5; ionic strength, 50, 100, 200, and 500 mM). Transmission electron microscopy demonstrated the successful preparation of complex nanoparticles and their spherical shape. Fourier transform infrared spectroscopy, fluorescence spectroscopy, and dissociation analysis results showed that the main driving forces of formed CN/BD nanoparticles were hydrogen bonding and hydrophobic interaction. Furthermore, the CN/BD nanoparticles (CN/BD mass ratio, 1:1; weight/weight) exhibited the lowest creaming index, and optical microscopy showed that it has the most evenly dispersed droplets after 7 d of storage, which indicates that the CN/BD nanoparticles had excellent emulsifying properties. Butyrylated dextrin forms complex nanoparticles with CN through hydrogen bonding and hydrophobic interaction to endow CN with superior properties. The results showed that it is possible to use pH-driven technology to form protein-polysaccharide complex nanoparticles, which provides some information on the development of novel food emulsifiers based on protein-polysaccharide nanoparticles. The study provided significant information on the improvement of CN properties and the development of emulsions based on CN.

Application of functionalized chitosan in food: A review

Environmental and sustainability issues have received increasing attention in recent years. As a natural biopolymer, chitosan has been developed as a sustainable alternative to traditional chemicals such as food preservation, food processing, food packaging, and food additives due to its abundant functional groups and excellent biological functions. This review analyzes and summarizes the unique properties of chitosan, with a particular focus on the mechanism of action for its antibacterial and antioxidant properties. This provides a lot of information for the preparation and application of chitosan-based antibacterial and antioxidant composites. In addition, chitosan is modified by physical, chemical and biological modifications to obtain a variety of functionalized chitosan-based materials. The modification not only improves the physicochemical properties of chitosan, but also enables it to have different functions and effects, showing promising applications in multifunctional fields such as food processing, food packaging, and food ingredients. In the current review, applications, challenges, and future perspectives of functionalized chitosan in food will be discussed.

Complexation of oligochitosan with sodium caseinate in alkalescent and weakly acidic media

Сomplexation of oligochitosan (OCHI) having the degree of acetylation (DA 26 %) with sodium caseinate (SC) at pH 5.8 and 7.2 is described and compared with the complexation of OCHI (DA 2 %) at pH 5.8. In the alkalescent medium, the complexation of OCHI (DA 26 %) is weaker and dualistic depending on SC concentration in the system. In the diluted alkalescent system, the formation of only soluble complexes is observed at OCHI/SC ratio ≤0.9. In the semi diluted one, the complexation results in the formation of insoluble complexes those composition changes symbatically with the OCHI/SC ratio in the system. At pH 5.8, OCHI/SC ratio in insoluble complexes remains the same regardless of OCHI/SC ratio in the solution. At pH 5.8, the electrostatic complexation weakens with an increase in DA and is completely suppressed at a high ionic strength. These results can be promising for construction of biodegradable protein/chitosan drug delivery systems.

Electrostatic Heteroaggregation: Fundamentals and Applications in Interfacial Engineering

The aggregation of oppositely charged soft materials (particles, surfactants, polyelectrolytes, etc.) that differ in one or more physical or chemical attributes, broadly referred to as electrostatic heteroaggregation, has been an active area of research for several decades now. While electrostatic heteroaggregation (EHA) is relevant to diverse fields such as environmental engineering, food technology, and pharmaceutical formulations, more recently there has been a resurgence to explore various aspects of this phenomenon in the context of interface stabilization and the development of functional materials. In this Feature Article, we provide an overview of the recent contributions of our group to this exciting field with particular emphasis on fundamental studies of electrostatic heteroaggregation between oppositely charged systems in the bulk, at interfaces, and across the bulk/interface. The influence of the size and shape of particles and the surface charge of heteroaggregates on the formation of Pickering emulsions and their utilization in the development of porous ceramics is discussed.

Effects of environmental stimuli on the physicochemical and rheological properties of chitosan-macroalgal polyphenol stabilized Pickering emulsion

In this study, Pickering emulsions stabilized by chitosan (CS), chitosan-Laminaria japonica polyphenols (CP) and chitosan-Ascophyllum nodosum polyphenols (CB) were fabricated. This study also evaluated the stability of CS, CP, and CB under different environmental factors including pH (2-9), NaCl concentrations (0-500 mM), heat treatments (50-100 °C) and storage period (0-8 weeks). The characterization on interfacial layer of emulsion droplets demonstrated that macroalgal polyphenols could combined with the amorphous regions of chitosan particles through hydrogen bond and electrostatic interactions, providing stronger dual wettability with enhanced ability of interfacial layer in stabilizing Pickering emulsions. All three emulsions showed best droplet distribution, highest emulsion stability and specific surface area at pH 6 and 0 mM NaCl concentration as fresh emulsion. Moreover, CS, CP, and CB exhibited the rheological behaviour of pseudoplastic fluids at different pH and NaCl concentration. It should be noted that CP and CB exhibited higher emulsion stability than CS under a variety of environmental stresses. Overall, this research proved that chitosan-macroalgal polyphenol co-stabilized Pickering emulsion had enhanced stability against various environmental stimuli, which could be utilized as potential delivery and protection system for hydrophobic bioactive compounds.

Conformation changes and emulsifying properties of myofibrillar proteins in water: Effects of electrostatic interaction with chitosan

Great interests have been attracted toward muscle protein in a water-soluble state with improved functionality for further designing meat protein fortified low-salt functional foods. In the present study, electrostatic interaction of chitosan (CH) with myofibrillar proteins (MP) in water aqueous solution was investigated, and the linked structure changes and emulsion stabilization of MP were studied. Results showed that the electrostatic interaction inhibited MP aggregation, and smaller particle size complexes were formed at pH 6.0, leading to the loss of β-sheet contents and recovery of α-helix contents with decreasing MP/CH mixing ratio (5:1 and 1:1). The tertiary structure confirmed the conformation changes of MP in which more hydrophobic groups and active sulfhydryl groups were exposed (P < 0.05), and the fluorescence was also quenched. With decreasing mixing ratio, the droplet size of emulsion decreased (P < 0.05), while the absorbed protein content increased (P < 0.05). After 7 d of storage, complex at a ratio of 1:1 displayed desirable emulsion stability, which could be due to the improved emulsifying capacity, enhanced electrostatic repulsion and steric effects. These findings provide a better understanding of conformation changes of MP in water aqueous solution induced by electrostatic interactions at mild acidic pH and help to fabricate stable protein/polysaccharide emulsification systems for further developing meat protein-based functional food to deliver health.

Improved Stabilization and In Vitro Digestibility of Mulberry Anthocyanins by Double Emulsion with Pea Protein Isolate and Xanthan Gum

There is significant evidence that double emulsion has great potential for successfully encapsulating anthocyanins. However, few research studies are currently using a protein-polysaccharide mixture as a stable emulsifier for double emulsion. This study aimed to improve the stability and in vitro digestibility of mulberry anthocyanins (MAs) by employing a double emulsion composed of pea protein isolate (PPI) and xanthan gum (XG). The influence of various XG concentrations (0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%) and different temperatures (5 °C, 25 °C, 45 °C, 65 °C) on the physical stability and the thermal degradation of MAs from double emulsions were investigated. In addition, the physicochemical properties of double emulsions and the release performance of MAs during in vitro simulated digestion were evaluated. It was determined that the double emulsion possessed the most stable physical characteristics with the 1% XG addition. The PPI-1% XG double emulsion, when compared to the PPI-only double emulsion, expressed higher thermal stability with a retention rate of 83.19 ± 0.67% and a half-life of 78.07 ± 4.72 days. Furthermore, the results of in vitro simulated digestion demonstrated that the MAs in the PPI-1% XG double emulsion were well-protected at oral and gastric with ample release found in the intestine, which was dissimilar to findings for the PPI-only double emulsion. Ultimately, it was concluded that the double emulsion constructed by the protein-polysaccharide system is a quality alternative for improving stability and absorption with applicability to a variety of food and beverage systems.

Physicochemical Properties and Oxidative Stability of an Emulsion Prepared from (-)-Epigallocatechin-3-Gallate Modified Chicken Wooden Breast Myofibrillar Protein

The deterioration of wooden breast myofibrillar protein (WBMP) causes a decline in its processing performance, and the protein becomes easier to oxidize. Previous studies have revealed that the use of (-)-epigallocatechin-3-gallate (EGCG) may improve the physicochemical properties and oxidative stability of proteins in aqueous solutions. The effects of varying concentrations (0.01%, 0.02%, 0.03%, and 0.04% w/v) of EGCG on the physicochemical properties of a WBMP emulsion (1.2% WBMP/10% oil) and the inhibition of lipid and protein oxidation were studied. The results revealed that a moderate dose of EGCG (0.03%) could significantly (p < 0.05) improve the emulsion activity index (4.66 ± 0.41 m2/g) and emulsion stability index (91.95 ± 4.23%), as well as reduce the particle size of the WBMP emulsion. According to the micrographs and cream index, 0.03% EGCG retarded the phase separation by stopping the aggregation of droplets and proteins, thus significantly improving the stability of WBMP emulsions. During storage at 50 °C for 96 h, 0.03% EGCG inhibited lipid oxidation (lipid hydroperoxide and 2-thiobarbituric acid-reactive substance formation) and protein oxidation (carbonyl formation and sulfhydryl loss). In contrast, lower and higher EGCG concentrations (0.01%, 0.02%, and 0.04%) demonstrated shortcomings (such as weak antioxidant capacity or protein over-aggregation) in improving the quality and oxidation stability of the emulsion. In conclusion, a moderate dose of EGCG (0.03%) can be used to improve the quality and shelf life of WBMP 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.

Garlic essential oil in water nanoemulsion prepared by high-power ultrasound: Properties, stability and its antibacterial mechanism against MRSA isolated from pork

Food-borne methicillin-resistance Staphylococcus aureus (MRSA) has caused significant health threats and economic loss in livestock and poultry products. Garlic essential oil (GEO) is an effective antibacterial agent but presents strong instability and hydrophobicity. In this study, GEO in water nanoemulsion (GEON) with good stability was produced by emulsification technique of high-power ultrasound. Its antibacterial activity and underlying mechanism against MRSA isolated from retailed pork were investigated. Results showed that ultrasonic treatment significantly reduced the particle size of GENO from 820.3 to 215.0 nm as time increased from 0 to 10 min. Comparatively, GEON of 10 min ultrasound was more stable than other GEONs (0, 1, 5 min) during 30 d storage. It also displayed good thermal stability and relatively good ion stability (NaCl, MgCl₂, and glucose). Antibacterial analysis showed that GEON (10 min) exhibited the best anti-MRSA activity among all GEONs, and the minimum inhibitory concentration of GEO in this nanoemulsion was 0.125 % (1.25 mg/mL). Treatment of GEON (10 min) significantly suppressed the cell proliferation of MRSA, which was mainly achieved by damaging the cell membrane as evidenced by membrane depolarization and considerable leakage of intracellular nucleic acids and protein. Laser scanning confocal microscope and scanning electron microscopy showed that treatment of GEON (10 min) significantly altered the membrane integrity and severely damaged the cellular membrane and structure. The present work illustrated that GEON produced by ultrasonic emulsification is a promising alternative to inhibit the contamination and spread of MRSA in livestock and poultry products.

Deacetylation and Desuccinylation of the Fucose-Rich Polysaccharide Fucopol: Impact on Biopolymer Physical and Chemical Properties

FucoPol is an acylated polysaccharide with demonstrated valuable functional properties that include a shear thinning fluid behaviour, a film-forming capacity, and an emulsion forming and stabilizing capacity. In this study, the different conditions (concentration, temperature, and time) for alkaline treatment were investigated to deacylate FucoPol. Complete deacetylation and desuccinylation was achieved with 0.02 M NaOH, at 60 °C for 15 min, with no significant impact on the biopolymer’s sugar composition, pyruvate content, and molecular mass distribution. FucoPol depyruvylation by acid hydrolysis was attempted, but it resulted in a very low polymer recovery. The effect of the ionic strength, pH, and temperature on the deacetylated/desuccinylated polysaccharide, d-FucoPol, was evaluated, as well as its emulsion and film-forming capacity. d-FucoPol aqueous solutions maintained the shear thinning behaviour characteristic of FucoPol, but the apparent viscosity decreased significantly. Moreover, contrary to FucoPol, whose solutions were not affected by the media’s ionic strength, the d-FucoPol solutions had a significantly higher apparent viscosity for a higher ionic strength. On the other hand, the d-FucoPol solutions were not affected by the pH in the range of 3.6–11.5, while FucoPol had a decreased viscosity for acidic pH values and for a pH above 10.5. Although d-FucoPol displayed an emulsification activity for olive oil similar to that of FucoPol (98 ± 0%) for an oil-to-water ratio of 2:3, the emulsions were less viscous. The d-FucoPol films were flexible, with a higher Young′s modulus (798 ± 152 MPa), a stress at the break (22.5 ± 2.5 MPa), and an elongation at the break (9.3 ± 0.7%) than FucoPol (458 ± 32 MPa, 15.5 ± 0.3 MPa and 8.1 ± 1.0%, respectively). Given these findings, d-FucoPol arises as a promising novel biopolymer, with distinctive properties that may render it useful for utilization as a suspending or emulsifier agent, and as a barrier in coatings and packaging films.

Physicochemical Properties, Stability and Texture of Soybean-Oil-Body-Substituted Low-Fat Mayonnaise: Effects of Thickeners and Storage Temperatures

With the increasing consumer demand for low-fat and low-cholesterol foods, low-fat mayonnaise prepared from soybean oil body (SOB) substitute for egg yolk has great consumption potential. However, based on previous studies, it was found that the stability and sensory properties of mayonnaise substituted with SOB were affected due to there being less lecithin and SOB containing more water. Therefore, this study investigated the effects of different ratios of xanthan gum, pectin and modified starch as stabilizers on the apparent viscosity, stability, texture and microstructure of SOB-substituted mayonnaise. It was found that the apparent viscosity and stability of SOB-substituted mayonnaise increased significantly when xanthan gum, pectin and modified starch were added in a ratio of 2:1:1. Meanwhile, the emulsified oil droplets of SOB-substituted mayonnaise were similar in size and uniformly dispersed in the emulsion system with different thickener formulations. In addition, the storage stability of SOB-substituted mayonnaise was explored. Compared with full egg yolk mayonnaise, SOB-substituted mayonnaise had better oxidative stability and bacteriostatic, which is important for the storage of mayonnaise. This study provided a theoretical basis for the food industry application of SOB. Meanwhile, this study provided new ideas for the development and storage of low-fat mayonnaise.

Biodegradable Nanoparticles Prepared from Chitosan and Casein for Delivery of Bioactive Polysaccharides

Ophiopogon japonicus polysaccharides (OJPs) have great anti-inflammation and immunomodulatory abilities. However, the low bioavailability of OJPs reduces its applicability in the biomedical and pharmaceutical fields. Chitosan (CS) has excellent mucoadhesive properties and absorption-enhancing ability in oral administration. Casein hydrolysate (CL) has good interfacial diffusivity and emulsifying ability, and can interact with polysaccharides to form complexes combining the individual properties of both. Therefore, chitosan and casein hydrolysate are good candidates for developing nanoformulations for oral delivery. In this study, bioactive polysaccharides (OJPs), CS and CL, were combined to prepare CS/OJPs/CL co-assembled biodegradable nanoparticles. The interactions between polysaccharides (CS and OJPs) and peptide (CL) resulted in the formation of nanoparticles with an average particle size of 198 nm and high OJPs loading efficiency. The colloidal properties of the nanoparticles were pH-dependent, which were changed significantly in simulated digestive fluid at different pH values. OJPs released from the CS/OJPs/CL nanoparticles were greatly affected by pH and enzymatic degradation (trypsin and lysozyme). The nanoparticles were easily internalized by macrophages, thereby enhancing the OJPs’ inhibitory ability against Ni²⁺-induced cytotoxicity and LPS-induced nitric oxide production. This study demonstrates that prepared polysaccharide/protein co-assembled nanoparticles can be potential nanocarriers for the oral delivery of bioactive polysaccharides with anti-inflammatory functions.

Enhancing thermal and emulsifying resilience of pomegranate fruit protein with gum Arabic conjugation

In this study, a controlled Maillard reaction was carried out to conjugate gum Arabic (GA) polymer to pomegranate protein isolate (PPI). The Maillard conjugates (MCs) were visualized by SEM and authenticity of the conjugates was assessed by NMR, FTIR, and XRD. To reveal the effect of the Maillard conjugation on the quality attributes of PPI, functional properties, thermal stability, and emulsifying behaviors of PPI and MCs were investigated. The oil binding capacity of conjugated protein (370.52%) was higher than that of protein alone (208.19%). While GA and PPI were completely degraded or decomposed at a temperature of 1000 °C, the MCs retained approximately half of the initial mass. MCs displayed higher emulsifying activity (42.71 m²/g) and emulsifying stability (90.17 (ESI30)), compared to PPI (32.61 m²/g) and (72.25 (ESI30)). Stability coefficient was significantly improved and reached from 0.64 R to 0.95 R with the usage of MCs in the emulsions. A lower centrifugal precipitation rate was determined in MCs emulsions (28.26%) compared to PPI emulsions (45.42%). Utilization of MCs instead of protein alone as a stabilizer in the oil-in-water emulsions was a logical approach for increasing their stability against environmental degradations including freeze-thaw cycle, pH, ionic, and temperature stress.

Rheological properties of polysaccharides from Pholiota nameko with different temperature extraction: Concentration, pH, temperature, and saltion

Cold and hot water extracted polysaccharides (CW-PNPs and HW-PNPs) were isolated from Pholiota nameko. The rheological properties of PNPs were investigated by steady shear and oscillatory rheological measurements. The PNPs exhibited typical non-Newtonian and shear-thinning behavior, which are affected by PNP concentration, temperature, pH value, salt ion, and concentration. Specifically, the apparent viscosity of the two PNPs solutions at concentration of 1% (w/w) was shown as HW-PNPs > CW-PNPs. The apparent viscosity of PNPs decreases under acidic and alkaline conditions and when the temperature rises; K⁺ and Na⁺ cause the apparent viscosity of CW-PNPs to decrease, while Ca²⁺ and Al³⁺ are opposite. The addition of four different salt ions all caused the apparent viscosity of the HW-PNPs to decrease. The results of dynamic rheological experiments show that G' and G″ showed slightly frequency dependency with G' exceeding G″ throughout the accessible range of frequency for CW-PNPs and HW-PNPs.

Modulation of Fabrication and Nutraceutical Delivery Performance of Ovalbumin-Stabilized Oleogel-Based Nanoemulsions via Complexation with Gum Arabic

Protein–polysaccharide complexes, which involve Maillard-type protein–polysaccharide conjugates and electrostatic protein–polysaccharide complexes, have the potential to stabilize oleogel-based nanoemulsions for nutraceutical delivery. Here, ovalbumin (OVA) and gum arabic (GA) were used to prepare OVA–GA conjugate (OGC) and OVA–GA mixture (OGM), followed by the fabrication of astaxanthin-loaded oleogel-based nanoemulsions. Carnauba wax (5% w/w) and rice bran oil were mixed to prepare food-grade oleogel. The successful preparation of OGC was verified by means of SDS-PAGE analysis and free amino groups determination. OGC endowed oleogel-based nanoemulsions with smaller emulsion droplets and higher stability during 30-day storage, implying more outstanding emulsifying capability than OGM. Both OGC-stabilized nanoemulsions and OGM-stabilized nanoemulsions could enhance the extent of lipolysis and the bioaccessibility of astaxanthin compared with oleogel. Meanwhile, OGC exhibited significantly better than OGM, which indicated that OGC-stabilized oleogel-based nanoemulsions possessed more desirable nutraceutical delivery performance than OGM-stabilized oleogel-based nanoemulsions. This study may fill a gap in the influence of different protein–polysaccharide complexes on oleogel-based nanoemulsions and contribute to deeper insights about novel oleogel-based nanoemulsions for their applications in the food industry.

Combined effect of chitosan and bovine serum albumin/whey protein isolate on the characteristics and stability of shrimp oil-in-water emulsion

The effect of bovine serum albumin (BSA) or whey protein isolate (WPI) at various concentrations (0.5%, 1.5%, and 3%; w/v) on the properties of shrimp oil-in-water emulsion was investigated. Both proteins at 1.5% showed the highest emulsifying properties. Moreover, the combined impact of chitosan (CS) at different levels (0.25%, 0.50%, 0.75%, and 1%; w/v) and 1.5% BSA or 1.5% WPI on emulsion properties was also studied. For the same protein used, those stabilized by BSA and WPI in conjunction with CS solution at 0.5% and 0.25% had the highest emulsion stability index, respectively. During storage for 28 days, the BSA-CSstabilized emulsion had higher turbidity, a*, b* but the lowest L* values compared to the WPI-CS counterpart (p < 0.05). Emulsion stabilized by the BSA-CS complex showed higher stability, as witnessed by lower d₃₂ and d₄₃ and lower flocculation factor and coalescence index, but it had a lower negative charge than those stabilized by the WPI-CS complex (p < 0.05). Oil droplets of the BSA-CS-stabilized emulsion showed a lower extent of size enlargement after storage. Rheological studies revealed viscous, shear-thinning, and non-Newtonian behavior of emulsions. Overall, emulsion stabilized by the BSA-CS complex had higher stability than that stabilized by the WPI-CS complex, and the former could maintain the stability of pigment in shrimp oil to some extent. PRACTICAL APPLICATION: Oil from shrimp hepatopancreas is a rich source of both astaxanthin and polyunsaturated fatty acids with health benefits. It can be used for the preparation of food emulsion, such as mayonnaise, with nutraceutical properties. However, emulsion stability determines the quality of the emulsion. The use of protein (bovine serum albumin) in conjunction with polysaccharides, especially chitosan at appropriate concentrations, was proven to improve shrimp oil-in-water emulsion during extended storage. Additionally, chitosan can act as an antioxidant to prevent the degradation of astaxanthin to some extent. This finding could be potentially beneficial to produce emulsion with high stability using protein-chitosan complexes.

Effect of pectin on the properties of nanoemulsions stabilized by sodium caseinate at neutral pH

The effect of different concentrations of low methoxyl pectin (LMP) on lipid oxidation and physical stability of sodium caseinate (CAS) stabilized nanoemulsions under neutral pH was investigated. The addition of pectin at low concentration (≤ 0.10 wt%) had no significant effect on the average size of nanoemulsions, but a slight size increase and phase separation were observed at higher concentrations of pectin (≥ 0.25 wt%). This result suggests that LMP can not adsorb at the oil/water interfacial CAS membrane at neutral pH. However, in the presence of LMP, the physical stability of nanoemulsions against high salt concentrations and freeze-thaw cycles was significantly enhanced. Moreover, nanoemulsions containing pectin have a better ability to inhibit lipid and protein oxidation than nanoemulsions without pectin after 3 weeks, and the lowest lipid hydroperoxide content was observed for nanoemulsions containing 0.25 wt% pectin.

Maillard-Type Protein-Polysaccharide Conjugates and Electrostatic Protein-Polysaccharide Complexes as Delivery Vehicles for Food Bioactive Ingredients: Formation, Types, and Applications

Due to their combination of featured properties, protein and polysaccharide-based carriers show promising potential in food bioactive ingredient encapsulation, protection, and delivery. The formation of protein–polysaccharide complexes and conjugates involves non-covalent interactions and covalent interaction, respectively. The common types of protein–polysaccharide complex/conjugate-based bioactive ingredient delivery systems include emulsion (conventional emulsion, nanoemulsion, multiple emulsion, multilayered emulsion, and Pickering emulsion), microcapsule, hydrogel, and nanoparticle-based delivery systems. This review highlights the applications of protein–polysaccharide-based delivery vehicles in common bioactive ingredients including polyphenols, food proteins, bioactive peptides, carotenoids, vitamins, and minerals. The loaded food bioactive ingredients exhibited enhanced physicochemical stability, bioaccessibility, and sustained release in simulated gastrointestinal digestion. However, limited research has been conducted in determining the in vivo oral bioavailability of encapsulated bioactive compounds. An in vitro simulated gastrointestinal digestion model incorporating gut microbiota and a mucus layer is suggested for future studies.