Mechanism of Formation and Stabilization of Nanoparticles Produced by Heating Electrostatic Complexes of WPI-Dextran Conjugate and Chondroitin Sulfate

Studies on the Properties and Stability Mechanism of Double Emulsion Gels Prepared by Heat-Induced Aggregates of Egg White Protein-Oligosaccharides Glycosylation Products

Multiple emulsions can dissolve some substances with different properties, such as hydrophilicity and lipophilicity, into different phases. They play an important role in protection, controlled release and targeted release of the encapsulated substances. However, it's poor stability has always been one of the main problems restricting its application in the food industry. For this reason, a heat-induced aggregate (HIA) of Maillard graft product of isomalto-oligosaccharides (IMO), as well as egg white protein (EWP), was used as hydrophilic emulsifier to improve the stability of W1/O/W2 emulsions. Moreover, gelatin was added into the internal aqueous phase (W1) to construct W1/O/W2 emulsion-gels system. The encapsulation efficiency of HIA-stabilized W1/O/W2 emulsions remained nearly unaltered, dropping by only 0.86%, significantly outperforming the conjugates and physical mixture of IMO and EWP in terms of encapsulation stability. The emulsion-gels system was constructed by adding 5% gelatin in the W1, and had the highest EE% and good salt and heat stability after 30 days of storage. This experiment provides guidance for improving the stability of W1/O/W2 emulsions system and its application in the package delivery of functional substances in the food field.

Complexes of glycated casein and carboxymethyl cellulose enhance stability and control release of anthocyanins

To improve the stability and sustained-release property of anthocyanins (ACNs), casein (CA) - dextran (DEX) glycated conjugates (UGCA) and carboxymethyl cellulose (CMC) were used to prepare ACNs-loaded binary and ternary complexes. The ACNs-loaded binary complexes (ACNs-UGCA) and ternary complexes (ACNs-UGCA-CMC) achieved by 8 min' ultrasonic treatment with 40 % amplitude. The binary and ternary complexes showed spherical structure and good dispersibility, with the average size of 121.2 nm and 132.4 nm respectively. The anthocyanins encapsulation efficiency of ACNs-UGCA-CMC increased almost 20 % than ACNs-UGCA. ACNs-UGCA-CMC had better colloidal stabilities than ACNs-UGCA, such as thermal stability and dilution stability. Simultaneously, both of the binary and ternary complexes significantly prevented anthocyanins from being degraded by heat treatment, ascorbic acid, sucrose and simulated gastrointestinal environment. The protective effect of ACNs-UGCA-CMC was more significant. Furthermore, ACNs-UGCA-CMC showed slower anthocyanins release in simulated releasing environment in vitro and a long retention time in vivo. Our current study provides a potential delivery for improving the stability and controlling release of anthocyanins.

Smart antimicrobial system based on enzyme-responsive high methoxyl pectin-whey protein isolate nanocomplex for fresh-cut apple preservation

The increase in pectin methylesterase (PME) activity on fresh-cut apple surface can smartly trigger the controlled release of bactericidal agents encapsulated within intelligent responsive Pickering emulsions. In this study, we developed a PME-responsive nanocomplex (W-H-II) to stabilize Pickering emulsion containing thyme essential oil (TEO), preserving fresh-cut apples. W-H-II, formed by heat-induced whey protein isolate (WPI) and high methoxyl pectin (HMP) (pH 4.5, 85 °C, 15 min, WPI:HMP ratio 1:2), exhibited good pH stability due to the stabilizing effects of hydrophobic, hydrogen bonding, and electrostatic interactions. The presence of PME triggered the demethylation of HMP within W-H-II, conferring PME response characteristics. Subsequently, a bacteriostasis experiment with pectinase-producing Bacillus subtilis provided evidence of PME-triggered TEO release from W-H-II-stabilized Pickering emulsion. Furthermore, microscopy techniques were employed to verify the demulsification behavior of the emulsion when PME activity ranged from 0.25 to 2.50 U mL-1. Finally, the PME-responsive TEO Pickering emulsion effectively preserved fresh-cut apples. Stored for 6 days at 5 °C and 10 °C, as the PME activity on the apple surface increased, the decay rate of the coated group was 0 %, with a total colony count below 3.0 log CFU g-1. This study introduces a novel intelligent preservation strategy for storing fresh-cut apples.

Stabilization of anthocyanins by simultaneous encapsulation-copigmentation via protein-polysaccharide polyelectrolyte complexes

This study prepared a series of polyelectrolyte complexes (PECs) composed of heated whey protein isolate (HWPI) and different polysaccharides for simultaneous encapsulation and copigmentation of anthocyanins (ATC) and their ultimate stabilization. Four polysaccharides including chondroitin sulfate, dextran sulfate, gum arabic, and pectin were chosen due to their abilities to simultaneously complex with HWPI and copigment ATC. At pH 4.0, these PECs were formed with an average particle size of 120-360 nm, the ATC encapsulation efficiency of 62-80%, and the production yield of 47-68%, depending on the type of polysaccharides. The PECs effectively inhibited the degradation of ATC during storage and when exposed to neutral pH, ascorbic acid, and heat. Pectin had the best protection, followed by gum arabic, chondroitin sulfate, and dextran sulfate. The stabilizing effects were associated with the hydrogen bonding, hydrophobic and electrostatic interactions between HWPI and polysaccharides, conferring dense internal network and hydrophobic microenvironment in the complexes.

Storage impact on egg white powder's physical and functional properties

BACKGROUND

Changes in storage temperature and time alter the functional properties of egg white powder (EWP) and determine its quality and shelf-life, finally affecting the consumer acceptance of the products made from EWP. In the present study, the EWP samples were stored at four different temperatures (-20, 4, 25 and 37 °C) for 60 days, and then the protein structural, physical and functional properties of EWP were measured and assessed further for correlation with storage conditions using heatmap.

RESULTS

The viscosity of the EWP solution increased after 30 days. Foaming ability and rheological properties increased first and then decreased compared to untreated samples with the prolonged storage time. Correlation analysis results indicated that the gel hardness, water holding capacity, foaming ability, emulsifying ability, particle size, dispersibility and viscosity of EWP were significantly related to storage time (P < 0.05). Only the gelation properties of EWP stored at 37 °C for 60 days changed significantly and were negatively related to its moisture content (P < 0.05). Additionally, the random coil content of EWP was positively correlated with particle size, moisture content, solubility and gel properties, whereas β-sheet was negatively correlated with them.

CONCLUSION

Compared to other temperatures, the functional properties of EWP were relatively stable under 4 °C. Therefore, the low temperature (4 °C) was selected as the most suitable storage temperature for EWP. The results of the present study could provide a theoretical basis for the shelf-life extension of EWP. © 2022 Society of Chemical Industry.

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.

Preparation of novel self-assembled albumin nanoparticles from Camellia seed cake waste for lutein delivery

The potential utilization value of Camellia seed cake was explored by extracting albumin (CSCA) to develop nanoparticles for lutein delivery. First, thermal property and amphiphilicity of CSCA were evaluated to guide nanoparticle preparation. Next, CSCA nanoparticles modified with chitosan (CS) were prepared through a thermally induced self-assembly method derived by electrostatic attraction and hydrophobic interaction. The optimized nanoparticles were prepared from CSCA:CS at a mass ratio of 2:1 with pH of 4.5, and an incubation temperature and time of 80 ℃ and 10 min, respectively. The nanoparticles had the highest effective loading capacity for lutein at 5.89 ± 0.78%, and the corresponding encapsulation efficiency was 43.82 ± 5.69%. The storage stability of lutein was improved by nanoparticle loading, and the bioaccessibility of lutein in simulated intestinal digestion increased from 26.8 ± 4.4% to 57.3 ± 9.6% after encapsulation into nanoparticles. These findings may facilitate the development of new and sustainable proteins from plant waste for delivery system applications.

Ovalbumin/carboxymethylcellulose colloids: Particle compactness and interfacial stability

A protein/polysaccharide colloidal particle was prepared via combined complex coacervation and heat-induction. When the ratio of ovalbumin (OVA) to carboxymethylcellulose (CMC) was at 1:2, loose flexible particles (low D_f) with low surface hydrophobicity were obtained. Conversely, dense and compact particles (high D_f) were easily formed at a higher OVA/CMC ratio. Only in the appropriate OVA/CMC ratio, pH will have a greater impact on the colloidal particles. At the pH value of 4.4, the OVA/CMC ratio had a greater impact on the colloidal particles compared to pH. The emulsion stabilized by loose particles had a mean particle size of 3888 nm and was easily flocculated and creamed. On the other hand, compact particles formed a stable emulsion, which had a higher exponent of Δr² (0.867) and could resist flocculation during the 7 days storage. As such, the results showed that stable emulsion could be realized by utilizing compact particles as emulsifiers.

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

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

Structure, function and enzymatic synthesis of glucosaccharides assembled mainly by α1 → 6 linkages - A review

A variety of glucosaccharides composed of glucosyl residues can be classified into α- and β-type and have wide application in food and medicine areas. Among these glucosaccharides, β-type, such as cellulose and α-type, such as starch and starch derivatives, both contain 1 → 4 linkages and are well studied. Notably, in past decades also α1 → 6 glucosaccharides obtained increasing attention for unique physiochemical and biological properties. Especially in recent years, α1 → 6 glucosaccharides of different molecular weight distribution have been created and proved to be functional. However, compared to β- type and α1 → 4 glucosaccharides, only few articles provide a systematic overview of α1 → 6 glucosaccharides. This motivated, the present first comprehensive review on structure, function and synthesis of these α1 → 6 glucosaccharides, aiming both at improving understanding of traditional α1 → 6 glucosaccharides, such as isomaltose, isomaltooligosaccharides and dextrans, and to draw the attention to newly explored α1 → 6 glucosaccharides and their derivatives, such as cycloisomaltooligosaccharides, isomaltomegalosaccharides, and isomalto/malto-polysaccharides.

Construction of Hohenbuehelia serotina polysaccharides-mucin nanoparticles and their sustain-release characteristics under simulated gastrointestinal digestion in vitro

In this study, Hohenbuehelia serotina polysaccharides-mucin nanoparticles (HSP-MC NPs) were fabricated based on hydrogen bonding and hydrophobicity effects for improving the bioavailability of HSP. The structural characteristics and morphology of HSP-MC NPs prepared by different conditions were respectively identified and observed. The results showed that HSP-MC NPs (HSP/MC, 1/1, w/w) presented the optimal physicochemical characteristics, with the encapsulation efficiency of 88.09 ± 0.01%, average particle size of 509.4 ± 9.76 nm and zeta potential of -20.6 ± 0.7 mV. Furthermore, HSP-MC NPs (HSP/MC, 1/1, w/w), belonged to non-crystalline substances, exhibited the excellent physicochemical stabilities against temperature, pH and ionic strength, and had the uniform spherical morphological characteristics. In addition, under simulated gastrointestinal digestion in vitro, HSP-MC NPs (HSP/MC, 1/1, w/w) showed the good sustained release performances, that might effectively improve the absorption rate of HSP. The present research is meaningful for designing the polysaccharides-loaded nano-delivery system based on natural non-toxic carrier that can be used in function food field.

Mild Enzyme-Induced Gelation Method for Nanoparticle Stabilization: Effect of Transglutaminase and Laccase Cross-Linking

Low-environment-sensitive nanoparticles were prepared by enzymatic cross-linking of electrostatic complexes of dextran-grafted whey protein isolate (WPI-Dextran) and chondroitin sulfate (ChS). The effect of transglutaminase (TG) and laccase cross-linking on nanoparticle stability was investigated. Covalent TG cross-linking and grafted dextran cooperatively contributed to the stability of nanoparticles against dissociation and aggregation under various harsh environmental conditions (sharply varying pH, high ionic strength, high temperature, and their combined effects). However, fragmentation induced by laccase treatment did not promote nanoparticle stability. Structural characterization showed that the compact structure promoted by TG-induced covalent isopeptide bonds repressed dissociation against varying environmental conditions and thermal-induced aggregation. Furthermore, the increasing α-helix and decreasing random coil contents benefited the formation of disulfide bonds, further contributing to the enhanced stability of nanoparticles cross-linked by TG, whereas weak hydrophobic interactions and hydrogen bonding as evidenced by the increase in β-sheet and microenvironmental changes were not able to maintain the stability of nanoparticles treated with laccase. Encapsulated cinnamaldehyde presented sustained release from TG-cross-linked nanoparticles, and the bioaccessibility was considerably enhanced to 50.7%. This research developed a novel mild strategy to enhance nanoparticle stability in harsh environments and digestive conditions, which could be an effective delivery vehicle for hydrophobic nutrients and drug applications in food and pharmaceutical industries.

Development of Nanocomplexes for Curcumin Vehiculization Using Ovalbumin and Sodium Alginate as Building Blocks: Improved Stability, Bioaccessibility, and Antioxidant Activity

Type I (Complex I) and type II nanocomplexes (Complex II) were created in this work for curcumin (Cur) delivery using ovalbumin (OVA, 1.0% w/w) and sodium alginate (ALG, 0.5% w/w) as building blocks. OVA was heated at 90 °C for 5 min at pH 7.0 and then coated with ALG at pH 4.2 to produce Complex I; OVA-ALG electrostatic complex was created at pH 4.0, which was treated at 90 °C for 5 min thereafter yielding Complex II. Complex I presented an irregular elliptical shape with a diameter of ∼250 nm, whereas Complex II adopted a defined spherical structure of a smaller size (∼200 nm). Complex II did not dissociate at the pH range of 5-7, which was different from Complex I. Cur was loaded into the nonpolar matrix of nanocomplexes through hydrogen bonding and hydrophobic interactions, and Complex II displayed a higher loading capacity than Complex I. Nanocomplexes were resistant to pepsinolysis during simulated gastrointestinal digestion, which enhanced the stability and controlled release of loaded Cur, thereby improving Cur bioaccessibility from ∼20% (free form) to ∼60%. Additionally, nanocomplexes contributed to the cellular antioxidant activity (CAA) of Cur by promoting its cellular uptake. The CAA of Cur was also better preserved in nanocomplexes especially in Complex II after digestion owing to the increased stability and bioaccessibility. Results from this work highlighted the effect of nanocomplex encapsulation on the performance of Cur and revealed the critical role of preparation method in the physicochemical attributes of nanocomplexes.

Comparative study on stabilizing ability of food protein, non-ionic surfactant and anionic surfactant on BCS type II drug carvedilol loaded nanosuspension: Physicochemical and pharmacokinetic investigation

Carvedilol (CAR) in its pure state has low aqueous solubility and extremely poor bioavailability which largely limit its clinical application. The aim of the study is to improve the dissolution rate and the bioavailability of CAR via preparing nanosuspensions with different stabilizers. Antisolvent precipitation-ultrasonication technique was used here. Attempts have been made to use food protein- Whey protein isolate (WPI) as a stabilizer in CAR loaded nanosuspension and also to compare its stabilizing potential with conventional nanosuspension stabilizers such as non-ionic linear copolymer-poloxamer 188 (PLX188) and anionic surfactant-sodium dodecyl sulfate (SDS). Optimized nanosuspensions showed narrow size distribution with particle size ranging from 275 to 640nm. Amorphous state of CAR nanocrystals which also improved the solubility by 16-, 25-, 55-fold accordingly was confirmed by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). From scanning electron microscopy (SEM), flaky shape of PLX188 and SDS nanosuspensions could be revealed but WPI nanosuspension was sphere-shaped. Up to 70% dissolution of loaded drug was observed within 15min in phosphate buffer (pH6.8). A pharmacokinetic study in rats indicated that both C_max and AUC_0-36 values of nanosuspensions were estimated to be 2-fold higher than those of reference, suggesting a significant increase in CAR bioavailability.

Protein Selectivity Controlled by Polymer Charge Density and Protein Yield: Carboxylated Polysaccharides versus Sulfated Polysaccharides

The effect of polymer charge density on protein selectivity in the presence of carboxylated polysaccharides (CPS) and sulfated polysaccharides (SPS) was investigated for Kunitz trypsin inhibitor/Bowman-Birk protease inhibitor (KTI/BBI, KBM). To determine the conditions for coacervation or precipitation as a function of polymer charge densities, turbidimetric titrations and Tricine-SDS-PAGE were used. Polymer charge density as well as chain flexibility greatly influenced the strength of interactions and protein recovery. Although charge compensation must occur for CPS-KBM complexes, SPS-KBM systems did not require conservation of charge neutrality. Despite their similar isoelectric points, KTI bound preferentially to CPS and SPS due to its higher affinity compared to BBI. Complexation of KBM with the polysaccharide with the lowest charge density, arabic gum, expectedly cannot realize the purification of BBI under conditions where binding to more highly charged polysaccharides occurs. This work will be beneficial to selective purification of target proteins through control of protein-polysaccharide complexation.