Effect of interactions between glycosylated protein and tannic acid on the physicochemical stability of Pickering emulsions

Ultrasound-assisted oligochitosan/casein complexes stabilized Pickering emulsion: Characterization, stability and its application for lutein delivery

Lutein is a natural pigment with various beneficial biological activities, but its poor water solubility, chemical instability, and low bioavailability limit its application in food processing. In this study, modified casein (CAS-OCS NPs)-based Pickering emulsions were constructed under the combined effect of TGase-type glycation and ultrasound treatment as delivery systems for lutein fortification. Pickering emulsions based on CAS-OCS NPs enhanced the encapsulation efficiency of lutein (87.04 ± 0.30 %). The modification treatments improved the emulsifying properties, environmental stability, and digestive stability, as well as the delivery capability of lutein and antioxidant activity in simulated in vitro gastrointestinal digestion. After glycation modification, the lutein release rate of CAS-OCS NPs-based Pickering emulsions after in vitro digestion was higher than that of untreated casein-based Pickering emulsions, and the maximum release rate was 55.44 ± 0.50 %. Moreover, the CAS-OCS NPs-based Pickering emulsions showed improved lutein bioaccessibility, reaching the maximum value of 58.52 ± 0.52 %. These findings demonstrated the suitability of TGase-type glycation and ultrasound treatment for the preparation of Pickering emulsions to deliver bioactive compounds.

Preparation and characterization of covalent starch-protein-tea polyphenol complexes with enhanced interfacial properties

In this study, covalent octenyl succinic anhydride starch-soy protein- (-)-Epigallocatechin-3-gallate (OSAS-SP-EGCG) complexes were synthesized by H2O2/ ascorbic acid radical grafting method. Particle size, ζ-potential, Fourier transform infrared, and thermogravimetric results proved the formation of covalent OSAS-SP-EGCG complexes. The results of scanning electron microscopy and atomic force microscopy confirmed that the particles of the covalent complexes (especially 1:4 complexes) were more uniformly distributed. Compared with single OSAS, the covalent complexes exhibited excellent antioxidant capacity (>70 %). Static/dynamic contact angle, dynamic interfacial tension and quartz crystal microbalance were used to characterize the interfacial properties of the samples. Results showed that the stronger hydrophobicity of the complexes resulted in lower interfacial tension, which was stabilized at 17 mN/m after 45 min. Among the complexes, 1:4 complexes showed the most visible interfacial properties, with the initial and equilibrium surface values increasing by 12.1 % and 24.3 %, respectively. Moreover, the saturated f displacement of 1:4 complexes reached 50.45 Hz. It was indicated that better interfacial adsorption capacity of the complexes allowed them to adsorb more quickly to the oil-water interface and form thicker and denser interfacial films. This work provides a promising avenue for improving the interfacial properties of covalent polysaccharide-protein-polyphenol complexes.

Effects of alcalase hydrolysis combined with TGase-type glycosylation of self-assembled zein for curcumin delivery: Stability, bioavailability, and antioxidant properties

In this study, zein was hydrolyzed by alcalase and conjugated to oligochitosan under transglutaminase (TGase) catalysis to construct novel self-assembly complex for the delivery of curcumin. The effects of enzyme hydrolysis and TGase-type glycosylation of zein/curcumin on the stability, bioavailability, and antioxidant properties were evaluated. The obtained glycosylated zein hydrolysate had a uniform distribution and small particle sizes. Structural analysis revealed that the primary forces within the curcumin-loaded glycosylated zein hydrolysate complex were electrostatic interactions, hydrogen bonding, and hydrophobic interactions. The prepared complex demonstrated excellent encapsulation efficiency for curcumin (82.19 %). Oligochitosan formed a protective layer around zein hydrolysate/curcumin complex through covalent binding, effectively resisting the degradation caused by gastric enzymes. This significantly increased the retention rate during the undigested stage and facilitated the release of curcumin in the intestine, thereby enhancing the bioavailability. This study offers new insights into using hydrolysis combined with TGase-type glycosylation of protein as a delivery system to protect hydrophobic nutrients.

Enhancing curcumin stability and bioavailability through chickpea protein isolate-citrus pectin conjugate emulsions: Targeted delivery and gut microecology modulation

The limited solubility, rapid metabolism, and poor bioavailability of curcumin restrict its application. In this study, we synthesized chickpea protein isolate (CPI)-citrus pectin (CP) conjugates to prepare an emulsion delivery system that enhances the stability and bioavailability of curcumin. The CPI-CP emulsion achieved a curcumin encapsulation efficiency of 86.15 %. Additionally, the stability of curcumin within CPI-CP emulsion was enhanced under conditions of thermal, UV irradiation, and oxidation. In vitro digestion demonstrated that the CPI-CP conjugates effectively preserved the interfacial film integrity during gastric digestion, facilitating targeted delivery of curcumin to the small intestine. This resulted in a substantial increase in curcumin bioavailability, from 50.60 % to 85.60 %. In vivo, the emulsion alleviated liver oxidative stress by improving antioxidant enzyme activity and promoted gut health through increased short-chain fatty acid production and modulation of gut microbiota. This research presents an effective strategy for enhancing the stability and bioavailability of curcumin and demonstrates the potential application of CPI-CP conjugates in delivery systems for bioactive substances.

Interfacial behavior and emulsifying properties of coconut protein glycated by polygalacturonic acid with different molecular weight

Glycosylation can be used to improve the emulsifying properties of protein by covalently binding with sugar. In this study, we prepared coconut protein (CP) -polygalacturonic acid (PA) conjugates by dry-heat method, studied the effect of PA with different molecular weight on the structure and functionality of CP, and characterized the interfacical behavior of CP at the oil-water interface to establish the relationship between interfacial behavior and emulsion stability. The results showed that different molecular weights of PA (28.4 ± 2.01 kDa, 20.3 ± 3.09 kDa, 16.3 ± 3.07 kDa, 11.6 ± 2.33 kDa) significantly affected the grafting degree between CP and PA (14.57 % ± 0.98 %, 53.74 % ± 0.1 %, 45.5 % ± 1.81 %, 36.54 % ± 0.38 %, respectively). The results of scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FT-IR) confirmed the successful preparation of PA-CP conjugates. The dynamic interfacial tension of the conjugate was lowest (11.03 ± 0.07 mN/m) at the lowest PA molecular weight (11.6 ± 2.33 kDa), which increased with the increase of molecular weight. The diffusion, penetration and rearrangement rates of the conjugate were the highest when the molecular weight of PA was 20.3 ± 3.09 kDa. Compared to mixtures, conjugates tended to form a more elastic and stable interfacial film at the oil-water interface. In addition, the glycosylation reaction could improve the emulsion stability, resulting in smaller droplets size and higher zeta potential. With the decrease of molecular weight of PA, the emulsifying performance of CP was also improved. In conclusion, this work can further expand the application of coconut protein in the food industry and indicate the direction for further development of pectin with different molecular weights in the food industry.

Recent advances of protein modification strategies to enhance the freezing stability of food emulsions: Principles, applications, and prospects

Emulsion-based foods typically employ proteins as their stabilizers, and their quality maintenance mostly relies on freezing conditions. Currently, improving the freezing stability of food emulsions through various strategies has been a topical issue in food science fields, and the modification targeting proteins is an essential research direction. This review discusses the destabilization mechanisms of food emulsions during freezing, including changes in the aqueous and oil phases, lipid oxidation, changes in pH and ionic strength, and denaturation or inactivation of proteins as emulsifiers. Then, it illustrates the role of the spatial structural properties of proteins and the formation of interfacial protein films in maintaining the freezing stability of emulsions. Moreover, this review highlights the effects of protein modification strategies on the freezing stability of emulsions and emulsion gels, including enzymatic hydrolysis treatment, glycosylation, salt and pH treatment, polyphenol addition, and physical treatment. It also discusses the further application of protein-modified Pickering emulsions in the food industry. In summary, modification treatments performed on proteins are effective in improving the freezing stability of food emulsions, and this area still has considerable room for exploration in the future, such as treatments involving emerging technologies or emerging substances and the synergistic effect of different treatments in maintaining emulsion freezing stability. This review will provide valuable theoretical insights into the production of high-quality and shelf-stable emulsion-based food products.

Interfacial mechanisms, environmental influences, and applications of polysaccharide-based emulsions: A review

To develop stable polysaccharide-based emulsions, many studies have focused on the interfacial behavior of adsorbed polysaccharides. This review first discussed the mechanism of polysaccharides self-assembly at the oil-water interface. It can be concluded that polysaccharides can form a thick and strong interfacial membrane that stabilizes emulsions through steric hindrance and electrostatic interactions. In particular, we also investigated the influence of various conditions (i.e., mechanical stress, heating, pH, enzymatic treatment, and ionic strength) on the architecture and properties of polysaccharide-based emulsions. Additionally, the interactions of polysaccharides with other molecules in the emulsion system were summarized, revealing that co-adsorption further changes their properties. Furthermore, current approaches for monitoring the behavior of adsorbed polysaccharides at the oil/water interface were reviewed, highlighting their advantages and limitations. Lastly, we emphasized the potential of polysaccharides for producing environmental-friendly emulsions in the food industry.

Fabrication and characterization of novel TGase-mediated glycosylated whey protein isolate nanoparticles for curcumin delivery

The aim of this study was to fabricate novel transglutaminase (TGase)-mediated glycosylated whey protein isolate (WPI) nanoparticles for the encapsulation and delivery of curcumin. The influences of glycosylation on the physiochemical properties, stability, bioavailability, and antioxidant properties of WPI nanoparticles loaded with curcumin were investigated. Composite nanoparticles exhibited uniform distribution and small particle sizes. The main driving forces for the formation of curcumin nanoparticles were electrostatic interactions, hydrogen bonding, and hydrophobic interactions. The encapsulation and loading efficiency of curcumin after TGase-type glycosylation were significantly increased in comparison to WPI-curcumin nanoparticles. Glycosylated WPI-curcumin nanoparticles had stronger antioxidant properties and stability to resist external environmental changes than WPI-curcumin nanoparticles. In addition, glycosylated WPI-curcumin nanoparticles showed a controlled release and enhanced curcumin bioavailability in vitro gastrointestinal digestion. This study provides novel insights for self-assembled glycosylated protein nanoparticles as delivery systems for protecting hydrophobic nutrients.

Enhancing the Stability of Litsea Cubeba Essential Oil Emulsions Through Glycosylation of Fish Skin Gelatin via Dry Maillard Reaction

Emulsions are widely utilized in food systems but often face stability challenges due to environmental stresses, such as pH, ionic strength, and temperature fluctuations. Fish skin gelatin (FSG), a promising natural emulsifier, suffers from limited functional properties, restricting its broader application. This study explored the enhancement of emulsion stability in Litsea cubeba essential oil systems through the glycosylation of fish skin gelatin (FSG) with dextran via the dry Maillard reaction. Among dextrans of varying molecular weights (10 kDa, 100 kDa, 200 kDa, and 500 kDa), the 200 kDa dextran exhibited the best emulsification performance, achieving a remarkable 160.49% increase in stability index. The degree of grafting (DG) increased with molecular weight, peaking at 34.77% for the 500 kDa dextran, followed by 23.70% for the 200 kDa variant. The particle size of the FSG-Dex 200 kDa conjugate emulsion was reduced to 639.1 nm, compared to 1009-1146 nm for the unmodified FSG, while hydrophobicity improved by 100.56%. The zeta potential values approached 30 mV, indicating enhanced stability. Furthermore, glycosylation significantly improved antioxidant activity, as evidenced by increased radical scavenging capacity in both DPPH and ABTS assays. These findings underscore the potential of glycosylated FSG as a natural emulsifier in food applications.

Study on the Structural Characteristics and Foaming Properties of Ovalbumin-Citrus Pectin Conjugates Prepared by the Maillard Reaction

This study explored the structural features and foaming properties of ovalbumin (OVA) and its glycosylated conjugates with citrus pectin (CP) formed through the Maillard reaction. The results demonstrated that OVA and CP were successfully conjugated, with the degree of grafting increasing to 43.83% by day 5 of the reaction. SDS-PAGE analysis confirmed the formation of high-molecular-weight conjugates. Fourier-transform infrared (FT-IR) and fluorescence spectroscopy further revealed alterations in the secondary and tertiary structures of OVA, including an enhanced β-sheet content, a reduced β-turn content, and the depletion of tryptophan residues. Moreover, the surface hydrophobicity of the OVA-CP conjugates significantly increased, enhancing foaming properties. Furthermore, the analysis of foaming properties exhibited that the Maillard reaction improved the foaming capacity of OVA to 66.22% and foaming stability to 81.49%. These findings highlight the potential of glycosylation via the Maillard reaction to significantly improve the foaming properties of OVA, positioning it as a promising novel foaming agent.

Enhancing the water dispersibility and intestinal targeting of pterostilbene using tannic acid-whey protein conjugates

In this study, three types of whey protein isolate (WPI)-tannic acid (TA) covalent conjugates (WPI-TA) were synthesized via alkaline treatment, free radical-induced method, and laccase induction. These conjugates were subsequently utilized in the antisolvent precipitation method to encapsulate pterostilbene (Pte). The structural and functional properties of these conjugates as carriers for intestinal-targeted Pte delivery were thoroughly evaluated. SDS-PAGE, total phenolic content measurement, grafting efficiency, and FT-IR analysis confirmed the successful formation of three distinct covalent conjugates. Among them, the laccase-induced WPI-TA conjugates exhibited the highest TA grafting efficiency. The particle size of this conjugate was measured at 115.25 nm with a PDI of 0.31. Upon encapsulation of Pte, this conjugate exhibited superior thermal stability, enhanced antioxidant properties, and sustained release within the gastrointestinal tract. The water solubility of Pte in these nanoparticles was found to be 361.19 times higher than that of free Pte, presenting a promising strategy for targeted intestinal delivery of Pte.

Structural and functional properties of whey protein isolate-inulin conjugates prepared with ultrasound or wet heating method

BACKGROUND

Whey protein isolate (WPI) generally represents poor functional properties such as thermal stability, emulsifying activity and antioxidant activity near its isoelectric point or high temperatures, which limit its application in the food industry. The preparation of WPI-polysaccharide covalent conjugates based on Maillard reaction is a promising method to improve the physical and chemical stability and functional properties of WPI. In this research, WPI-inulin conjugates were prepared through wet heating method and ultrasound method and their structural and functional properties were examined.

RESULTS

In conjugates, the free amino acid content was reduced, the high molecular bands were emerged at sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), new C-N bonds were formed in Fourier-transform infrared (FTIR) spectroscopy, and fluorescence intensity was reduced compared with WPI. Furthermore, the result of circular dichroism (CD) spectroscopy also showed that the secondary structure of conjugates was changed. Conjugates with ultrasound treatment had better structural properties compared with those prepared by wet heating treatment. The functional properties such as thermal stability, emulsifying activity index (EAI), emulsion stability (ES) and antioxidant activity of conjugates with wet heating treatment were significantly improved compared with WPI. The EAI and ES of conjugates with ultrasound treatment were the highest, but the thermal stability and antioxidant activity were only close to that of the conjugates with wet heating treatment for 2 h.

CONCLUSION

This study revealed that WPI-inulin conjugates prepared with ultrasound or wet heating method not only changed the structural characteristics of WPI but also could promote its functional properties including thermal stability, EAI, ES and antioxidant activity. © 2024 Society of Chemical Industry.

Preparation of oil-in-water emulsions stabilized by faba bean protein-grape leaf polyphenol conjugates: pH-, salt-, heat-, and freeze-thaw-stability

BACKGROUND

Plant proteins are being increasingly utilized as functional ingredients in foods because of their potential health, sustainability, and environmental benefits. However, their functionality is often worse than the synthetic or animal-derived ingredients they are meant to replace. The functional performance of plant proteins can be improved by conjugating them with polyphenols. In this study, the formation and stability of oil-in-water emulsions prepared using faba bean protein-grape leaf polyphenol (FP-GLP) conjugates as emulsifiers. Initially, FP-GLP conjugates were formed using an ultrasound-assisted alkali treatment. Then, corn oil-in-water emulsions were prepared using high-intensity sonication (60% amplitude, 10 min) and the impacts of conjugate concentration, pH, ionic strength, freezing-thawing, and heating on their physicochemical properties and stability were determined.

RESULTS

Microscopy and light scattering analysis showed that oil-in-water emulsions containing small oil droplets could be formed at conjugate concentrations of 2% and higher. The addition of salt reduced the electrostatic repulsion between the droplets, which increased their susceptibility to aggregation. Indeed, appreciable droplet aggregation was observed at ≥ 50 mmol/L sodium chloride. The freeze-thaw stability of emulsions prepared with protein-polyphenol conjugates was better than those prepared using the proteins alone. In addition, the emulsions stabilized by the conjugates had a higher viscosity than those prepared by proteins alone.

CONCLUSION

This study showed that FP-GLP conjugates are effective plant-based emulsifiers for forming and stabilizing oil-in-water emulsions. Indeed, emulsions formed using these conjugates showed improved resistance to pH changes, heating, freezing, and salt addition. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Enhancing the emulsion properties and bioavailability of loaded astaxanthin by selecting the reaction sequence of ternary conjugate emulsifiers in nanoemulsions

This study investigated the effects of the conjugate reaction sequences of whey protein concentrate (WPC), epigallocatechin gallate (EGCG) and dextran (DEX) on the structure and emulsion properties of conjugates and the bioaccessibility of astaxanthin (AST). Two types of ternary covalent complexes were synthesised using WPC, EGCG and DEX, which were regarded as emulsifiers of AST nanoemulsions. Results indicated that the WPC-DEX-EGCG conjugate (referred to as 'con') exhibits a darker SDS-PAGE dispersion band and higher contents of α-helix (6%), β-angle (24%) and random coil (32%), resulting in a greater degree of unfolding structure and fluorescence quenching. These findings suggested WPC-DEX-EGCG con had the potential to exhibit better emulsification properties than WPC-EGCG-DEX con. AST encapsulation efficiency (76.22%) and bioavailability (31.89%) also demonstrated the superior performance of the WPC-DEX-EGCG con emulsifier in nanoemulsion delivery systems. These findings indicate that altering reaction sequences changes protein conformation, enhancing the emulsification properties and bioavailability of AST.

Preparation and Properties of Walnut Protein Isolate-Whey Protein Isolate Nanoparticles Stabilizing High Internal Phase Pickering Emulsions

To enhance the functional properties of walnut protein isolate (WalPI), hydrophilic whey protein isolate (WPI) was selected to formulate WalPI-WPI nanoparticles (nano-WalPI-WPI) via a pH cycling technique. These nano-WalPI-WPI particles were subsequently employed to stabilize high internal phase Pickering emulsions (HIPEs). By adjusting the mass ratio of WalPI to WPI from 9:1 to 1:1, the resultant nano-WalPI-WPI exhibited sizes ranging from 70.98 to 124.57 nm, with a polydispersity index of less than 0.326. When the mass ratio of WalPI to WPI was 7:3, there were significant enhancements in various functional properties: the solubility, denaturation peak temperature, emulsifying activity index, and emulsifying stability index increased by 6.09 times, 0.54 °C, 318.94 m2/g, and 552.95 min, respectively, and the surface hydrophobicity decreased by 59.23%, compared with that of WalPI nanoparticles (nano-WalPI), with the best overall performance. The nano-WalPI-WPI were held together by hydrophobic interactions, hydrogen bonding, and electrostatic forces, which preserved the intact primary structure and improved resistance to structural changes during the neutralization process. The HIPEs stabilized by nano-WalPI-WPI exhibited an average droplet size of less than 30 μm, with droplets uniformly dispersed and maintaining an intact spherical structure, demonstrating superior storage stability. All HIPEs exhibited pseudoplastic behavior with good thixotropic properties. This study provides a theoretical foundation for enhancing the functional properties of hydrophobic proteins and introduces a novel approach for constructing emulsion systems stabilized by composite proteins as emulsifiers.

Revealing the mechanism of the lutein protective function of epicatechin-fructan glycosylated soybean protein isolate

Lutein possesses various physiological activities but is susceptible to light degradation, thermal degradation, and oxidative degradation. As such, protecting the activity of lutein-based products using natural extracts has become a current research. In this study, lutein was protected by complexing inulin-type fructan (ITF), soybean protein isolate (SPI), and epicatechin (EC), and the protection mechanism of epicatechin-fructan glycosylated soybean protein isolate (EC-GSPI) toward lutein was elucidated comprehensively. The results showed that the addition of EC delayed the degradation of lutein. The results of light stability experiments showed that increased EC significantly enhanced the storage time of the GSPI-Lutein system from 4 to 13 days. Additionally, the effect of EC on glycosylated soybean 7S globulin (G7S) and glycosylated soybean 11S globulin (G11S) was assessed. The light stability of G11S-Lutein and G7S-Lutein after the addition of EC was from G11S > G7S → G7S > G11S. Furthermore, the proteins purified from SPI interacted differently with EC and ITF, with soybean 7S globulin (7S) mainly interacting with EC and soybean 11S globulin (11S) mainly interacting with ITF. EC-GSPI-Lutein exhibited a good protective effect, probably due to the occurrence of hygrothermal Maillard between ITF and 11S, providing a porous structure for lutein storage. At the same time, the binding of EC to 7S significantly enhanced the antioxidant property of the solution and the stability of the protein secondary structure, thereby prolonging the storage time of lutein.

An innovative Pickering W/O/W nanoemulsion co-encapsulating hydrophilic lysozyme and hydrophobic Perilla leaf oil for extending shelf life of fish products

A Pickering water-in-oil-in-water nanoemulsion co-encapsulating lysozyme (LYS) and Perilla leaf oil (PO) was prepared using whey protein isolate-tannin acid conjugated nanoparticles (WPI-TA NPs) as emulsifiers, called LYS-PO-NE, and subsequently analyzed. The nano size and multiple phases was confirmed based on the results of confocal laser scanning microscope, scanning electron microscope, and droplet size analysis. LYS-PO-NE had high encapsulation efficiencies of 89.36 % (PO) and 43.91 % (LYS) and both could be released at a slow and continuous rate. The PO addition increased the droplet size, and the LYS addition delayed the release of PO. LYS-PO-NE also showed good storage, pH, thermal, and salt stability, and an effective combined bactericidal activity of LYS and PO against spoilage bacteria. Furthermore, the results of chilled salmon storage experiments indicated that LYS-PO-NE could extend the shelf life of chilled salmon to at least 6 days, demonstrating the potential in the shelf life for fish products.

Characterization and emulsifying ability evaluation of whey protein-pectin conjugates formed by glycosylation

Glycosylation is a method that enhances the functional properties of proteins by covalently attaching sugars to them. This study aimed at preparing three conjugates (WP-HG, WP-SBP, and WP-RGI) by dry heating method to research the influence of different pectin structures on the functional properties of WP and characterize properties and structures of these conjugates. The research results manifested that the degree of glycosylation (DG) of HG, SBP and RGI were 13.13 % ± 0.07 %, 23.27 % ± 0.3 % and 36.39 % ± 0.3 % respectively, suggesting that the increase of the number of branch chains promoted the glycosylation reaction. The formation of the conjugate was identified by the FT-IR spectroscopy technique. And SEM showed that WP could covalently bind to pectin, resulting in a smoother and denser surface of the conjugates. The circular dichroism analysis exhibited that the glycosylation reaction altered the secondary structure of WP and decreased the α-Helix content. This structural change in the protein spatial conformation led to a decrease in the hydrophobicity of protein surface. But the addition of pectin further regulated the hydrophilic-hydrophobic ratio on the surface of the protein, thus improving the emulsification properties of WP. In addition, the glycosylation could improve the stability of the emulsion, giving it a smaller droplet size, higher Zeta-potential and more stable properties. In a word, this study pointed out the direction for the application of different pectin structures in the development of functional properties of glycosylation products in food ingredients.

Novel Pickering emulsion stabilized by glycosylated whey protein isolate: Characterization, stability, and curcumin bioaccessibility

Pickering emulsions prepared from protein-polysaccharide complexes have attracted increasing attention. In this study, whey protein isolates (WPI) were modified with oligochitosan using transglutaminase (TGase)-type to fabricate Pickering emulsions, and loaded with curcumin. The curcumin/protein ratio of 1:25 and oil phase fraction (φ = 17 %) are the most optimal condition for emulsions stabilization, and particle size of glycosylated WPI emulsion was 31.70 μm. Glycosylated WPI emulsion had the highest encapsulation efficiency (96.64 %) of curcumin. Microstructure analysis showed that glycosylated WPI had small droplets covered by dense interface layers. The modified WPI emulsions exhibited optimal emulsifying properties and emulsion stability, which effectively inhibited the premature water-oil stratification in emulsion. In vitro digestion results showed that WPI-oligochitosan complexes enhanced curcumin bioaccessibility (40.34 %). The antioxidant activity of glycosylated WPI emulsions was significantly increased. The results of this study provide helpful references for applying glycosylated WPI-stabilized Pickering emulsions, which can be used as transport carriers of curcumin.

Construction of protein-, polysaccharide- and polyphenol-based conjugates as delivery systems

Natural polymers, such as polysaccharides and proteins, have been used to prepare several delivery systems owing to their abundance, bioactivity, and biodegradability. They are usually modified or combined with small molecules to form the delivery systems needed to meet different needs in food systems. This paper reviews the interactions of proteins, polysaccharides, and polyphenols in the bulk phase and discusses the design strategies, coupling techniques, and their applications as conjugates in emulsion delivery systems, including traditional, Pickering, multilayer, and high internal-phase emulsions. Furthermore, it explores the prospects of the application of conjugates in food preservation, food development, and nanocarrier development. Currently, there are seven methods for composite delivery systems including the Maillard reaction, carbodiimide cross-linking, alkali treatment, enzymatic cross-linking, free radical induction, genipin cross-linking, and Schiff base chemical cross-linking to prepare binary and ternary conjugates of proteins, polysaccharides, and polyphenols. To design an effective target complex and its delivery system, it is helpful to understand the physicochemical properties of these biomolecules and their interactions in the bulk phase. This review summarizes the knowledge on the interaction of biological complexes in the bulk phase, preparation methods, and the preparation of stable emulsion delivery system.

High internal phase Pickering emulsions stabilised by ultrasound-induced soy protein-β-glucan-catechin complex nanoparticles to enhance the stability and bioaccessibility of curcumin

AIMS

To evaluate the potential applications of soy protein-glucan-catechin (SGC) complexes prepared with different ultrasound times in stabilising high internal phase Pickering emulsion (HIPPE) and delivering curcumin.

METHODS

The SGC complexes were characterised by particle size, morphology, zeta potential, Fourier transform infra-red, and fluorescence spectroscopy. Formation and stability of curcumin emulsions were monitored by droplet size, microstructure, rheological property, lipid oxidation, and in vitro digestion.

RESULTS

Short-time ultrasound-induced complexes (SGC-U15) exhibited a small size and wettability of ∼82.5°. The chemical stability and bioaccessibility of curcumin was greatly improved by SGC-U15-stabilised HIPPEs, even after 70 days of storage, heating at 100 °C for 30 min, ultraviolet irradiation for 120 min, and in vitro digestion, owing to the formation of elastic gel-like structure at the oil/water interfaces.

CONCLUSION

Our findings may contribute to the design of emulsion-based delivery systems using ultrasound-induced protein-polysaccharide-polyphenol complexes.

Insights into the Mechanism Underlying the Influence of Glycation with Different Saccharides and Temperatures on the IgG/IgE Binding Ability, Immunodetection, In Vitro Digestibility of Shrimp (Litopenaeus vannamei) Tropomyosin

Tropomyosin (TM) is a heat-stable protein that plays a crucial role as a major pan-allergen in crustacean shellfish. Despite the high thermal stability of the TM structure, its IgG/IgE binding ability, immunodetection, and in vitro digestibility can be negatively influenced by glycation during food processing, and the underlying mechanism remains unclear. In this study, TM was subjected to glycosylation using various sugars and temperatures. The resulting effects on IgG/IgE-binding capacity, immunodetection, and in vitro digestibility were analyzed, meanwhile, the structural alterations and modifications using spectroscopic and LC-MS/MS analysis were determined. Obtained results suggested that the IgG/IgE binding capacity of glycosylated TM, immunodetection recovery, and in vitro digestibility were significantly reduced depending on the degree of glycosylation, with the greatest reduction occurring in Rib-TM. These changes may be attributable to structural alterations and modifications that occur during glycosylation processing, which could mask or shield antigenic epitopes of TM (E3: 61-81, E5b: 142-162, and E5c: 157-183), subsequently reducing the immunodetection recognition and digestive enzyme degradation. Overall, these findings shed light on the detrimental impact of glycation on TMs potential allergenicity and digestibility immunodetection and provide insights into the structural changes and modifications induced by thermal processing.

Preparation, Characterization and Antioxidant Activity of Glycosylated Whey Protein Isolate/Proanthocyanidin Compounds

A glycosylated protein/procyanidin complex was prepared by self-assembly of glycosylated whey protein isolate and proanthocyanidins (PCs). The complex was characterized through endogenous fluorescence spectroscopy, polyacrylamide gel electrophoresis, Fourier infrared spectroscopy, oil-water interfacial tension, and transmission electron microscopy. The results showed that the degree of protein aggregation could be regulated by controlling the added amount of procyanidin, and the main interaction force between glycosylated protein and PCs was hydrogen bonding or hydrophobic interaction. The optimal binding ratio of protein:PCs was 1:1 (w/w), and the solution pH was 6.0. The resulting glycosylated protein/PC compounds had a particle size of about 119 nm. They exhibited excellent antioxidant and free radical-scavenging abilities. Moreover, the thermal denaturation temperature rose to 113.33 °C. Confocal laser scanning microscopy (CLSM) images show that the emulsion maintains a thick interface layer and improves oxidation resistance with the addition of PCs, increasing the application potential in the functional food industry.

A review of protein-phenolic acid interaction: reaction mechanisms and applications

Phenolic acids (PA) are types of phytochemicals with health benefits. The interaction between proteins and PAs can cause minor or extensive changes in the structure of proteins and subsequently affect various protein properties. This study investigates the protein/PA (PPA) interaction and its effects on the structural, physicochemical, and functional properties of the system. This work particularly focused on the ability of PAs as a subgroup of phenolic compounds (PC) on the modification of proteins. Different aspects including the influence of structure affinity relationship and molecular weight of PA on the protein interaction have been discussed in this review. The physicochemical properties of PPA change mainly due to the change of hydrophilic/hydrophobic parts and/or the formation of some covalent and non-covalent interactions. Furthermore, PPA interactions affecting functional properties were discussed in separate sections. Due to insufficient studies on the interaction of PPAs, understanding the mechanism and also the type of binding between protein and PA can help to develop a new generation of PPA. These systems seem to have good capabilities in the formulation of low-fat foods like high internal Phase Emulsions, drug delivery systems, hydrogel structures, multifunctional fibers or packaging films, and 3 D printing in the meat processing industry.