High-temperature glycosylation modifies the molecular structure of ovalbumin to improve the freeze-thaw stability of its high internal phase emulsion

Rennet-assisted modification for enhanced freeze-thaw stability in sodium caseinate-stabilized high internal phase emulsions

Poor freeze-thaw stability seriously limits the application of Pickering emulsions in the frozen food industry. This study developed sodium caseinate-stabilized high internal phase emulsions (NaCas-HIPEs) with enhanced freeze-thaw stability through rennet modification. The freeze-thaw stability and 3D printing properties of NaCas-HIPEs significantly improved as rennet addition increased from 0 % to 0.5 (w/v). NaCas-HIPEs with 0.5 % rennet even maintained a stable oil-in-water emulsion structure after five freeze-thaw cycles. Changes in enthalpy and freezing/thawing point demonstrated that rennet modification improved freeze-thaw stability by reducing the ice crystal formation. Additionally, increasing rennet concentration significantly enhanced the apparent viscosity and viscoelasticity of NaCas-HIPEs, restricting ice crystal growth and preventing droplet aggregation during freezing and thawing. This improvement is attributed to the strong gel networks formed by rennet-induced casein between droplets, as shown by the cryo-SEM microscopy and SDS-PAGE analysis. This study presents an effective method for producing freeze-thaw stable emulsions, offering promising applications in the rapidly growing ready-to-eat food industry.

Recent progress in protein-based high internal-phase Pickering emulsions: Composition, stabilization, applications, and future trends

Protein-based high internal-phase Pickering emulsions (HIPPEs) have attracted widespread attention in recent years because they exhibit unique advantages for 3D printing and dysphagia food, including moist, soft, and creamy texture, good swallowing behavior, and excellent 3D printing effect. HIPPEs stability vastly influences its 3D printing accuracy, texture, and swallowing behavior. This review aims to comprehensively explore crucial factors influencing the formation and stability of HIPPEs, presenting reasonable strategies to enhance HIPPEs stability. Our emphasis lies in uncovering the relationship between protein-based particles' interfacial behavior, HIPPEs stability, and the application of HIPPEs on 3D printing and dysphagia food. Furthermore, the convergence of 3D printing and dysphagia foods expected to deepen, facilitating development of HIPPEs-based dysphagia food. Although application prospect of HIPPEs is very wide, looking ahead, there are many areas where further research is still required: (1) exploring more sources of protein fibrils, microalgae and insect proteins as Pickering particles to stabilize HIPPEs; (2) constructing mathematical model that unraveling the relationship between particles' interfacial behavior and HIPPEs stability; (3) combining dual-nozzle 3D printing with infill structure to modify the texture behavior and obtain more attractive appearance of HIPPEs-based dysphagia foods; (4) linking rheological behavior with oral processing and swallowing will be a research trend for exploring the texture and mouthfeel of dysphagia foods at different stages of oral processing; (5) developing evaluation system connected with oral processing behavior of dysphagia foods; (6) exploring the nutrition retention and texture behavior of dysphagia foods during 3D printing, post-processing, and chewing/swallowing process.

Elucidation on the quality improvement of dumpling wrappers by glycosylated potato protein under freeze-thaw cycle treatment

Dumplings are the favorite quick-frozen food for people in many countries. However, the formation and recrystallization of ice crystals damage the quality of dumpling wrappers during storage. Research has shown that proteins and polysaccharides can improve the quality of frozen dough and that the Maillard reaction can improve the functional properties of proteins and polysaccharides. Therefore, the effects of glycosylated protein between potato protein and xanthan gum (PXM) on the overall changes in dumpling wrappers during freeze-thaw cycles (FT) were studied in this study. The results showed that the addition of PXM (1 %) slowed the deterioration of texture and rheological properties and reduced the cooking loss rate and freezable water content of dumpling wrappers during FT, thus improving the texture quality of dumpling wrappers. Moreover, the addition of PXM delayed the changes in the contents of free sulfhydryl (SH) and disulfide (SS) bonds during storage, weakening the damage to the secondary structure and network structure of the protein. The reason for this difference may be that protein glycosylation significantly increases the zeta potential (13.5 %), surface hydrophobicity (63.9 %), emulsifying activity (192.6 %) and emulsification stability (116.7 %) of potato protein (PP). These results suggest that the application of the glycosylated protein provides a potentially feasible approach to improve the quality of frozen dumpling.

Maillard reaction conjugates of millet bran globulin and Arabic gum for curcumin encapsulation: Physicochemical characterization, storage stability, and in vitro digestion

In this study, millet bran globulin (MBG) and Arabic gum (AG) conjugates were prepared through the Maillard reaction (MR) and applied to curcumin-loaded Pickering emulsions. The effect of MR on MBG-AG conjugates (MBG-AG con) was evaluated by the degree of grafting (DG), the absorbance of intermediate reactants, and the browning index. The emulsifying properties of MBG-AG con with different DGs were assessed using the emulsifying activity index (EAI) and emulsifying stability index (ESI). Curcumin-loaded Pickering emulsions were prepared using optimized conjugates. Results indicated that MR enhanced the conjugates emulsifying properties, leading to improved emulsion performance. Compared to MBG, the optimized conjugates exhibited approximately 252.3 % and 167.1 % increases in EAI and ESI, respectively. The formation of MBG-AG con was confirmed through polyacrylamide gel electrophoresis, Fourier transform infrared, and fluorescence spectroscopy. Morphological changes before and after MR were observed through scanning electron microscopy. In comparison to MBG-stabilized emulsions, conjugate-stabilized emulsions exhibited smaller droplets, higher curcumin encapsulation efficiency (over 80 %), and better apparent viscosity. During simulated digestion, the bioavailability of curcumin reached 88.67 % in Pickering emulsions stabilized by 5 % conjugates. This study demonstrated the potential application of MBG-AG con prepared via MR in stabilizing Pickering emulsions, providing new theoretical insights into curcumin encapsulation.

Collaborative stabilizing effect of trehalose and myofibrillar protein on high internal phase emulsions: Improved freeze-thaw stability and 3D printability

This study investigated the improvement of adding trehalose (Tre) on freeze-thaw (F-T) stability and 3D printability of myofibrillar protein (MP)-based high internal phase emulsions (HIPEs), also the underlying mechanism. Appropriate Tre addition formed thicker shell-like structure around MP by hydrogen bonds, and induced protein unfolding to ameliorate amphiphilicity. Additionally, Tre promoted the MP diffusion to interface to reduce interfacial tension. After interface saturation, Tre inducing MP rearrangement contributed more to form compact interface layer. Larger interface coverage increased hydrophobic interactions between droplets, constructing stronger MP-Tre-HIPEs gel network, inhibiting more free water to form ice crystals, confirmed by reduced destabilization index and freezing point. Such gel network enhanced their own viscoelasticity and thixotropic recovery, exhibiting superior printing accuracy. Conversely, excessive Tre aggregates (15 %-20 %) competed with MP for interfacial adsorption and filled between interfacial layer of adjacent droplets, weakening gel network. These findings expanded MP-HIPEs high-value application in frozen-foods and 3D printing.

Structural and functional changes induced by different ultrasound-frequency-assisted xylose-glycation inhibits lysinoalanine formation in Tenebrio molitor protein

We explored the effects of sonication-assisted xylose (Xyl) grafting on the structure and functionality of Tenebrio molitor protein (MP). Different ultrasound frequencies (20, 25, 28, 20/25, 20/28, 25/28, 20/25/28 kHz) were used, and the inhibition mechanism of ultrasound-assisted Xyl grafting on the formation of lysinoalanine (LAL) was explored. The results suggested that the turbidity and browning products of MP significantly increase, with MP-Xyl-20 kHz exhibiting the highest grafting degree (43.78 %). Compared with MP, the total sulfhydryl content of MP-Xyl and MP-Xyl-20 kHz was significantly improved by 21.90 % and 98.80 % (P < 0.05). Circular Dichroism, Fourier Transform Infrared Spectroscopy, SEM, and AFM analysis showed changes in MP conformation following various frequencies ultrasound-assisted glycosylation. Notably, emulsifying capacity, stability, and foaming ability of MP-Xyl-20 kHz were significantly enhanced by 97.08 %, 48.03 %, and 55.01 %, respectively, compared with MP. The glycol-conjugated MP treated with ultrasound-assisted glycosylation (MP-Xyl-25/28 kHz) had the lowest LAL content (7.19 μg/mg), representing a 56.56 % and 46.70 % decrease compared to the control MP and MP-Xyl, respectively. The content of LAL exhibited a positive correlation with surface hydrophobicity, whereas it demonstrated a negative correlation with sulfhydryl and carbonyl groups. These findings indicated that sonication-assisted xylose improved the functional characteristics of MP, and the inhibition effect on LAL formation. The outcome of the study could be very beneficial in the modification of MP for food industrial applications.

Structural modification of whey protein isolate via electrostatic complexation with Tremella polysaccharides and its effect on emulsion stability at pH 4.5

Emulsions play an important role in food systems by encapsulating and delivering active compounds, but maintaining their stability under various conditions can be challenging. This study explored how the concentrations of Tremella polysaccharides (TPs) (0-0.75 %) affects the structural of whey protein isolate (WPI) and the stability of their emulsions at pH 4.5. At this pH, electrostatic interactions between WPI and TPs exposed hydrophobic groups within the protein, increased β-sheet contents, and improved the hydrophilic-hydrophobic balance, which enhanced emulsifying performance. WPI-TPs complexes (WTS) showed a high emulsifying activity index (57.85 m2/g) and emulsion stability index (82.03 %). Compared to WPI-only emulsions, WTS emulsions had smaller particle sizes, lower Turbiscan Stability Index (TSI) values, and higher viscoelasticity, thermal stability, freeze-thaw stability, and re-emulsification capacity. Importantly, when the TPs concentration in WTS emulsions exceeded 0.375 %, the TSI value dropped below 1, showing no particle migration or peak thickness, indicating full emulsion stability. These findings suggest that TPs help stabilize WPI emulsions near their isoelectric point (pH 4.5) and offer a promising approach to improving WPI functionality in acidic environments. The WTS system provides a reliable way to stabilize emulsions under acidic conditions, supporting the development of natural, stable emulsifiers for food applications.

Soy protein gels based on ultrasonic treatment: Effects of Ca2+ and 11S/7S ratio on gel structures and digestive properties

This study aimed to explore the impact of varying Ca2+ concentrations and 11S/7S ratios on the gel performance of soybean protein gels (SPGs) under ultrasonication (400 W, 15 min) and to clarify the mechanisms involved. Results showed Ca2+ addition altered the structure of soybean 11S/7S protein gels. Low Ca2+ levels increased the turbidity, hardness, and water retention of the gels, whereas high levels disrupted the orderly aggregation of 11S/7S proteins, creating a rough, porous network. The effect of Ca2+ was more pronounced with a higher 11S ratio, significantly influencing turbidity, disulfide bonding, and gel hardness. Conversely, 7S-rich gels showed reduced sensitivity to Ca2+. In vitro digestion and SDS-PAGE results indicated that 7S globulin's α, α', and β subunits were more digestible than the A and B subunits of 11S globulin. In conclusion, ultrasound combined with Ca2+ can enhance the cross-linking degree between 11S and 7S globulin, forming a dense network structure.

Preparation of mayonnaise with excellent thermal and storage stability from egg yolk-amino acid complex: Rheology, interfacial property, microstructure and lutein delivery

In this paper, egg yolk-amino acid (betaine or proline) complex was prepared at different pasteurization temperatures (68, 72 and 76 °C). Then complexes were applied to stabilized mayonnaise emulsion system. The results demonstrated that liquid egg yolk (LEY) protein structure gradually aggregated, molecular flexibility increased by 5 %, interfacial tension and intermolecular force enhanced remarkably with growth of pasteurization temperature. Compared with LEY, egg yolk-amino acid complex exhibited a more flexible structure with lower interfacial tension and superior molecular wettability. Complexes stabilized mayonnaise emulsion displayed excellent rheological property, homogeneous droplet distribution, smaller average particle size and higher (about 10 °C) thermal denaturation temperature (Td). In terms of thermal stability, oil binding capacity (OBC) of heated betaine mayonnaise (HBM) and heated proline mayonnaise (HPM) was approximately 20 % higher than that of heated control mayonnaise (HCM). Notably, the group of HBM thermal stability was generally excellent. During storage, mayonnaise might be an intermediate unstable state before emulsion breakage. In vitro digestion results illustrated that bioaccessibility of lutein delivered by BM-72 and PM-72 was 48.9 % and 37.0 % higher than CM-72, respectively. The results will provide reference for preparation of mayonnaise by egg yolk-amino acid complex as a carrier to deliver fat-soluble substances to improve bioaccessibility.

Preparation of high internal phase emulsions based on high-temperature glycation-modified egg white protein: Structural characteristics, stability, and β-carotene bioavailability under multi-parameter regulation

In recent years, freeze-thaw stability of high internal phase emulsions (HIPEs) has gained increasing attention. High-temperature glycosylation-modified proteins have shown to produce stable HIPEs. This study examines the effects of high-temperature glycosylation on egg white protein (EWP) and fructo-oligosaccharides (FO), focusing on how pH and EWP/FO ratios affect the structure of glycosylated EWPs (GEWPs) and HIPEs stability. Specifically, strong alkaline conditions promoted the glycosylation reaction, with the highest DG value at pH 11.0. At pH 5.0, close to the isoelectric point of EWP, GEWPs could not successfully stabilize HIPEs. However, they stabilized HIPEs under other pH conditions, with the best freeze-thaw stability and flocculation resistance when EWP ≥ FO. At pH 3.0, HIPEs had high viscosity and storage modulus, but phase transitions occurred after freeze-thaw when EWP ≤ FO. GEWPs-stabilized HIPEs formed gel structures with elastic properties upon thermal induction. Encapsulation experiments with β-carotene demonstrated that HIPEs prepared from GEWPs showed potential in DPPH and ABTS+ radical scavenging, improving β-carotene stability and bioavailability. Our findings show that GEWPs-stabilized HIPEs offer excellent stability, rheological properties, and carrier performance, with enhanced applications through optimized emulsifiers and preparation processes.

Effect of fat replacement in high internal phase emulsions constructed by high temperature saccharification of grafted proteins on gel properties and flavor profiles of sausages

In order to mitigate the risk of cardiovascular diseases associated with excessive saturated fatty acid intake, utilizing high internal phase emulsions (HIPEs) as a substitute for animal fat in producing high-quality fat-substituted meat products is an ideal approach. This study involves the preparation of glycosylation products of egg white protein (EWP) through saccharification at high temperatures in the presence of fructooligosaccharides (FO). The resulting glycation products of EWP were employed to create colloidal particles, forming HIPEs, which were further utilized to induce the formation of HIPEs gels (HIPEs-Gs). The study investigated the effects of substituting different ratios (25%, 50%, 75%, and 100%) of animal fat with HIPEs and HIPEs-Gs on the gel properties and flavor characteristics of sausages. Results showed that, compared to the control group, substituting fat with HIPEs significantly improved the gel properties, cooking yield, and G' of sausages, while excessive HIPEs-Gs substitution yielded negative effects. Low-field nuclear magnetic resonance results also demonstrated that adding HIPEs improved water and oil distribution in the sausage batter, enhancing protein's binding capacity with water. Scanning electron microscope revealed that HIPEs substitution led to a denser gel network with smaller pores, effectively "locking in" more water. Analysis of volatile compounds indicated accelerated release of aromatic compounds, alkanes, sulfides, and lipids when fat was substituted with HIPEs and HIPEs-Gs. Electronic tongue analysis suggested that HIPEs-Gs substitution reduced response values for umami and saltiness. In conclusion, compared to HIPEs-Gs, using HIPEs as a fat substitute improves the quality of sausages.

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.

Freeze-thaw stability of high-internal-phase emulsion stabilized by chickpea protein microgel particles and its application in surimi

BACKGROUND

Future applications of high-internal-phase emulsions (HIPEs) are highly regarded, but poor freeze-thaw stability limits their utilization in frozen products. This study aimed to characterize the structure of chickpea protein microgel particles (HCPI) induced by NaCl and to assess its impact on the freeze-thaw stability of HIPEs.

RESULTS

The results showed that NaCl induction (0-400 mmol L-1) increased the surface hydrophobicity (175.9-278.9) and interfacial adsorbed protein content (84.9%-91.3%) of HCPI. HIPEs prepared with HCPI induced by high concentration of NaCl exhibited superior flocculation index and centrifugal stability, and their freeze-thaw stability was better than that of natural chickpea protein. The increase in NaCl concentration reduced the droplet aggregation and coalescence index of the freeze-thaw emulsions, diminishing the precipitation of oil from the emulsion. Linear and nonlinear rheology showed that the strengthened gel structure (higher G' values) restricted water flow and counteracted the damage to the interfacial film by ice crystals at 100-400 mmol L-1 NaCl, thus improving the viscoelasticity of the freeze-thaw emulsions. Finally, the thawing loss of surimi gel with HCPI-200 HIPE was reduced by 2.04% compared to directly adding oil.

CONCLUSION

This study provided a promising strategy to improve the freeze-thaw stability of HIPEs and reduce the thawing loss of frozen products. © 2024 Society of Chemical Industry.

Ultrasound-assisted glycosylation of ovalbumin and dextran conjugate carrier for anthocyanins and their stability evaluation

Anthocyanins (AC) are vulnerable to degradation when affected by external factors. The present study employed ultrasound-assisted glycosylation of ovalbumin (OVA) and dextran (Dex) to generate conjugate carrier for AC to improve its stability. The results showed that sonication significantly improved the progression of Maillard reaction to OVA. Compared to traditional glycosylation, ultrasound treatment showed a higher degree of grafting, a lower number of free-SH, and smaller particle size and uniform distribution. The SDS-PAGE results indicated covalent interaction. Intrinsic fluorescence (INF), Fourier transform infrared spectroscopy (FTIR), and Circular dichroism (CD) analysis results suggested that ultrasound-assisted glycosylation altered the OVA structure. The scanning electron microscope (SEM) and X-ray diffractometer (XRD) observed that the ultrasound-assisted complex had a more compact and smoother structure and protein unfolding were better. The protein solubility increased significantly after glycosylation. Thermal gravimetric analysis (TGA) and Differential scanning calorimetry (DSC) indicated that the glycosylated conjugates can significantly improve the thermal stability of AC In addition, the AC showed an improved processing and storage stability when conjugated with glycosylated carrier. The glycosylated protein-anthocyanins complex may help provide new ideas and scientific basis for the development of naturally sourced anthocyanins-relevant products in pharmaceutical and food industry applications.

A comprehensive review on freeze-induced deterioration of frozen egg yolks: Freezing behaviors, gelation mechanisms, and control techniques

Over the years, the production of eggs has increased tremendously, with an estimated global egg production of 9.7 billion by 2050. Further processing of shell eggs to egg products has gained growing popularity. Liquid egg yolks, an innovative form of egg replacement, still suffer from short shelf-life issues, and freezing has been applied to maintain freshness. An undesirable phenomenon called "gelation" was found during the production of frozen egg yolks, which has attracted numerous scholars to study its mechanism and quality control methods. Therefore, we comprehensively reviewed the history of the studies on frozen egg yolks, including the production procedure, the fundamentals of freezing, the gelation mechanism, the factors affecting gelation behaviors, and the techniques to control the gelation behaviors of frozen egg yolks. Reporting the production procedure and freezing fundamentals of frozen egg yolks will give readers a better understanding of the science and technological aspects of frozen egg yolks. Furthermore, a comprehensive summary of the mechanism of egg yolk gel formation induced by freeze-thawing and relevant control techniques will provide insights to researchers and manufacturers in the field of frozen egg processing.

High freeze-thaw stability of Pickering emulsion stabilized by SPI-maltose particles and its effect on frozen dough

Pickering emulsions with good freeze-thaw stability are essential in frozen food applications. This study developed a high freeze-thaw stabilized soy protein isolate (SPI)-maltose (M) Pickering emulsion and applied it to frozen doughs to investigate and reveal its impacts on the processing properties of the frozen dough. The results showed that after the freeze-thaw cycle, with a volume ratio of 1:2 of SPI to M, the appropriate amount of M changed the structure of SPI. This resulted in the Pickering emulsion prepared by the SPI exhibiting the least droplet coalescence and the best freeze-thaw stability. The results of dough rheological properties, textural properties, and binding capacity with water demonstrated that Pickering emulsions effectively inhibited the loss of gluten protein network structure in the dough after freeze treatment and increased the binding capacity of gluten proteins with starch and water in the dough. The best results were obtained with the incorporation of 3 % SPI-M high freeze-thaw stability, where the amount of bound water following three freeze-thaw cycles was 4.27 times higher than in doughs without Pickering emulsion. Overall, this study is significant for enhancing the freeze-thaw stability of Pickering emulsions stabilized by proteins and providing a new application route for Pickering emulsions.

Effects of freezing on the gelation behaviors of liquid egg yolks affected by saccharides: thermal behaviors and rheological and structural changes

Monitoring and controlling the freezing process and thermal properties of foods is an important means to understand and maintain product quality. Saccharides were used in this study to regulate the gelation of liquid egg yolks induced by freeze‒thawing; the selected saccharides included sucrose, L-arabinose, xylitol, trehalose, D-cellobiose, and xylooligosaccharides. The regulatory effects of saccharides on frozen egg yolks were investigated by characterizing their thermal and rheological properties and structural changes. The results showed that L-arabinose and xylitol were effective gelation regulators. After freeze‒thawing, the sugared egg yolks exhibited a lower consistency index and fewer rheological units than those without saccharides, indicating controlled gelation. Weaker aggregation of egg yolk proteins was confirmed by smaller aggregates observed by confocal laser scanning microscopy and smaller particle sizes. Saccharides alleviated the freeze-induced conversion of α-helices to β-sheets in egg yolk proteins, exposing fewer Trp residues. Overall, L-arabinose showed the greatest improvement in regulating the gelation of egg yolks, followed by xylitol, which is correlated with its low molecular weight.

Pickering emulsion with high freeze-thaw stability stabilized by xanthan gum/lysozyme nanoparticles and konjac glucomannan

In this study, freeze-thaw cycle experiments were conducted on food-grade Pickering emulsions co-stabilized with konjac glucomannan (KGM) and xanthan gum/lysozyme nanoparticles (XG/Ly NPs). The rheological properties, particle size, flocculation degree (FD), coalescence degree (CD), centrifugal stability, Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and microstructure of Pickering emulsion stabilized by KGM before and after freeze-thaw were characterized. It was found that as the concentration of KGM increased, the flocculation degree (FD) and coalescence degree (CD) of the emulsion decreased after the freeze-thaw cycle compared to the control sample, and the microscopic images showed that the droplets became smaller and less affected by the freeze-thaw cycles. The rheological and water-holding properties also confirmed that the KGM-added emulsions still had a strong gel network structure and prevented the separation of the continuous and dispersed phases of the droplets after freezing and thawing. Freeze-thaw treatments had a negative effect on the stable emulsion of XG/Ly NPs, while the addition of KGM improved the freeze-thaw stability of the emulsion, which provided a theoretical basis for the development of emulsion products with high freeze-thaw stability.

Quinoa protein/polysaccharide electrostatic complex stabilized vegan high internal phase emulsions for 3D printing: Role of complex state and gelling-type polysaccharides

Rational selection of the complex state and polysaccharide type may enhance the performance of electrostatic complex stabilized high internal phase emulsions (HIPEs). Herein, quinoa proteins were extracted to form electrostatic complexes separately with three gelling-type polysaccharides to fabricate HIPEs. Results showed that the complexes in soluble state (pH 8.4-5.6) exhibited moderate size, high negative potential and enhanced protein hydrophobicity, and could achieve HIPEs with 84% oil phase upon acidification to pH 6 at low concentrations. Its excellent interfacial structure enhanced stability during heating, freeze-thawing and long-term storage, and exhibited promising 3D printing potential. Furthermore, the complexes formed by sulfated polysaccharide carrageenan had higher amphiphilicity than those formed by carboxylated polysaccharide pectin or sodium alginate, and their stabilized HIPE had preferable droplet size, stability and 3D printing resolution than its counterparts. This study may provide new insights into the performance enhancement of protein/polysaccharide electrostatic complex stabilized HIPEs.

Effects of glycation method on the emulsifying performance and interfacial behavior of coconut globulins-fucoidan complexes

Coconut globulins (CG) possesses potential as an emulsifier but has not been utilized well. In this study, the emulsifying performance of glycated CG-fucoidan (CGF) complexes, and the relationship between emulsifying stability and interfacial behavior were investigated. The results showed that the grafting of fucoidan increased the molecular weight of CG, and decreased the zeta potential and fluorescence intensity. With the higher glycosylation degree, the fucoidan modified CG exhibited better emulsifying stability and higher viscosity. Moreover, the result of adsorption kinetics revealed that elasticity was the main property of the interface layer. Compared to CG, CGF complexes with high degree of glycosylation had thicker interfacial layer on the oil-water interface. A thicker elastic interfacial layer may be beneficial to the emulsion stability, owing to the strong interaction of electrostatic repulsion and steric hindrance between oil droplets. These findings may provide useful information for glycated CGF complexes as emulsifiers in functional food.

High-temperature glycosylation of saccharides to modify molecular conformation of egg white protein and its effect on the stability of high internal phase emulsions

This paper investigates the freeze-thaw stability of oil-in-water emulsions stabilized by high-temperature wet heating glycosylation products. Glucose (Glu), D-fructose (Fru), xylose (Xyl), maltodextrin (MD), oligofructose (FO), and oligomeric isomaltulose (IMO) were chosen as sugar sources for the glycosylation reaction with egg white proteins (EWPs) at 120 °C to prepare the GEWPs. The study reveals that the type of sugar significantly influences the Maillard reactions with EWPs. The degree of glycosylation was highest in the Xyl group with the greatest reducing capacity and lowest in the MD, FO, and IMO groups. High-temperature wet glycosylation treatment induced changes in the secondary and tertiary structures of EWP. Elevated temperature exposed hydrophobic groups within the protein, while covalent binding of hydrophilic carbohydrates via the Maillard reaction decreased the protein's H0 value. Improved foaming and emulsifying properties were attributed to the increase in α-helix content, disulfide bond formation, and reduced surface tension. Emulsions prepared from GEWPs exhibited higher apparent viscosity and G' compared to those from natural EWPs, with the GEWP/Xyl group showing the highest values. After freeze-thaw treatment, the GEWP/Fru and GEWP/FO groups demonstrated superior stability and reduced freezing point, along with minimal microstructural alterations. These findings underscore the importance of sugar type in the stability of high internal phase emulsions (HIPEs) stabilized by GEWPs, indicating that a tailored Maillard reaction can yield stabilizers with exceptional freeze-thaw stability for emulsions.

Changes in structural, rheological, and gel properties of egg white protein induced by preheating in the dry state

The knowledge of fundamental rheological concepts is essential to understand the gelling process of egg white proteins (EWP), which can be used to further manipulate the gel performance with desired sensorial attributes. In this study, the rheological and gel properties of EWP as influenced by heating in the dry state were investigated. The structural changes in dry heated EWP (DEWP) were also characterized in terms of morphology, protein stability, and protein microenvironment. The results showed that moderate dry heating induced linear aggregation of DEWP and decreased the denaturation temperature (Td) and enthalpy of denaturation (ΔH). Furthermore, the cross-linking on protein surface led to nonpolar microenvironment of hydrophobic groups, which lays the foundation of improved gel properties. The specific outcomes include the increase in the G'max and the G''max values, k'/k'' values of DEWP dispersions, gel hardness and gumminess of DEWP gels and a decrease in gelation temperature of DEWP dispersions. However, few changes were found in the springiness and cohesiveness of the DEWP gels with increasing dry heating time. Notably, gels prepared with DEWP also had better digestibility. Overall, these results can provide theoretical basis for quality control and sensory evaluation of DEWP in the food industry.

Glycation Improved the Interfacial Adsorption and Emulsifying Performance of β-Conglycinin to Stabilize the High Internal Phase Emulsions

This study investigated the interfacial adsorption and emulsifying performance of glycated β-conglycinin (7S) with D-galactose (Gal) at various times. Results indicated that glycation increased the particle sizes and zeta potentials of glycated 7S by inducing subunit dissociation. Glycation destroyed the tertiary structures and transformed secondary structures from an ordered one to a disordered one, leading to the more flexible structures of glycated 7S compared with untreated 7S. All these results affected the structural unfolding and rearrangement of glycated 7S at the oil/water interface. Therefore, glycated 7S improved interfacial adsorption and formed an interfacial viscoelasticity layer, increasing emulsifying performance to stabilize high internal phase emulsions (HIPE) with self-supportive structures. Furthermore, the solid gel-like network of HIPE stabilized by glycated 7S led to emulsification stability. This result provided new ideas to improve the functional properties of plant proteins by changing the interfacial structure.