Protein glycosylation: a promising way to modify the functional properties and extend the application in food system

Preparation of an aqueous colloidal dispersion of myofibrillar proteins: A synergistic strategy integrating nonenzymatic glycation and exogenous amino acids

This study explores the possibility of exogenous lysine combined with nonenzymatic glycation to prepare an aqueous colloidal dispersion of meat protein. The results indicate that compared to the MPs aqueous solution, the aqueous colloidal dispersion possesses outstanding dispersion and stability. Results from structural analysis and microscopic observation show that l-lysine can promote the swelling and dissociation of MPs and form an entanglement network due to intermolecular bonding. Glycation by introducing hydrophilic dextran molecules leads to steric hindrance, inhibiting the self-assembly of myosin. Furthermore, the order of the reactions is critical; the addition of l-lysine can improve the degree of subsequent glycation, and the dextran molecules introduced during the glycation process also provide additional intermolecular forces for the entangled network. In summary, exogenous lysine combined with glycation is an effective strategy for preparing aqueous colloidal dispersions of MPs, improving their dispersibility and stability in a fluid state.

Impaired cellular barriers and blocked metabolic pathways contribute to inhibition of carvacrol-loaded nanoemulsions stabilized by soy protein isolate / chitooligosaccharide conjugate on S. putrefaciens

In this study, soy isolate protein / chitooligosaccharide (SPI/COS) glycosylated conjugates was prepared and employed as an emulsifier to stabilize carvacrol-loaded nanoemulsions (CNE-SPI/COS). The antibacterial properties and mechanism of CNE-SPI/COS against S. putrefaciens was investigated. The results of microbial growth curves and confocal laser scanning microscopy (CLSM) results showed that CNE-SPI/COS effectively inhibited the growth of S. putrefaciens and the killing effect of CNE-SPI/COS on S. putrefaciens was concentration-dependent. Field emission scanning electron microscopy (FESEM) images showed that CNE-SPI/COS caused folds, shrinkage, rupture and even lysis of S. putrefaciens. The results showed that CNE-SPI/COS inhibited the growth and reproduction of S. putrefaciens mainly through three targets: (i) the reduction of alkaline phosphatase (AKP) activity and protein leakage indicated that CNE-SPI/COS disrupted the integrity of cell wall and cell membrane; (ii) the reduction of intracellular protein and ATP content indicated that CNE-SPI/COS interfered the synthesis of intracellular nutrient and synthesis of energy-supplying substances; (iii) changes in the activities of succinate dehydrogenase, pyruvate kinase, and glucose 6-phosphate dehydrogenase indicated that CNE-SPI/COS impeded the normal cellular metabolic pathways such as the tricarboxylic acid cycle, the glycolytic pathway, and the pentose phosphate pathway, and the decrease in superoxide dismutase activity indicated that CNE-SPI/COS disrupted the defense system against oxidative stress. In conclusion, the encapsulation of carvacrol into the nanoemulsion system can provide theoretical support and methodological guidance for the application of nanoemulsions in microbial decontamination of aquatic products.

Recent advances in modification of plant-based proteins for improved encapsulation performance

Encapsulation is a useful technique for protection, stabilization and controlling the release of bioactive compounds and food ingredients particularly sensitive to environmental factors such as heat, light and temperature. A wide variety of biopolymers can be used as wall materials in encapsulation, among which proteins are an essential group. In recent years, with the increasing interest in concepts such as plant-based nutrition and sustainability, the use of plant proteins in encapsulation has also increased. Proteins obtained from plant sources are sustainable, easily accessible, and low cost compared to animal-based counterparts; additionally, they are biodegradable, renewable, and biocompatible. However, there are some limitations regarding their functional properties such as solubility, emulsifying, gelling, and film-forming abilities. Various physical, chemical and enzymatic modification methods are used to improve the functional properties of plant proteins and to expand their use in encapsulation technologies. In this review, plant-based proteins (PBPs) and their use in encapsulation are discussed. Different modification techniques can improve the encapsulation performance of plant proteins; however, process parameters should be optimized. The most commonly studied physical, chemical, enzymatic and combined modification methods are sonication, Maillard conjugation, enzymatic hydrolysis and pH-shifting combined ultrasonication, respectively. The use of combined modification methods is a promising approach for improvement of the encapsulation performance of PBPs.

Application of fat replacers in low-fat starch-based foods: Type, formulation and action mechanism on food quality

Fat is an essential component in the processing of starch-based products. However, excessive fat intake is not beneficial to human health. Therefore, the development of fat replacers (FRs) and healthy and delicious low-fat starch-based products has become a research focus. The regulation mechanisms of fat on the quality of starch-based products, and types and formulations of FRs used in starch-based products were summarized. Based on the interaction with starch, the regulation mechanism of FRs on the quality of starch-based products and main quality evaluation parameters of low-fat starch-based products formed by these FRs were discussed. Oil-free systems (particles, polymers, hydrocolloids) and oil-containing systems (emulsions, emulsion gels, oleogels) are the main FRs used in starch-based foods. Their formulations depend mainly on the interaction between the components (polysaccharides, proteins and fats). Regulation mechanisms of FRs on the quality of starch-based products are mainly due to that their addition changes the structure, physicochemical and functional properties of starch. Microstructure, textural, rheological and tribological properties, sensory evaluation, fat digestion and calories, and nutrition are main elements of quality evaluation of low-fat starch-based products containing FRs. Next, it is necessary to systematically explore the regulation mechanism of FRs with different structures and properties on the quality of starch-based products based on molecular simulation and machine learning. More interdisciplinary collaborations, such as molecular chemistry, nutrition and nanotechnology, need to be used to guide the design of FRs and the development of low-fat starch-based products.

Effects of different saccharides glycosylation modified soy protein isolate on its structure and film-forming characteristics

With the serious impact of traditional plastic packaging on the environment, the development of safe, environmentally friendly and degradable packaging materials has become a research hotspot. Glycosylation reaction has been explored by researchers because of its green, efficient and simple. In this study, the film-forming properties of soy protein isolate (SPI) were improved by glycosylation modification. Different types of saccharides (monosaccharides: glucose, fructose, xylose; oligosaccharides: maltose, fructooligosaccharide, xylooligosaccharide; polysaccharide: gum arabic) were introduced into the SPI by moist heat method. The results show that the xylose-modified SPI film has the best performance in mechanical properties and thermal stability, and its tensile strength is increased to 5.1 MPa, and its elongation reached 117.8 %. Structural analysis revealed that glycosylation resulted in a decrease in α-helix content of SPI, while β-sheets and random coils increased, forming a tighter cross-linked network, improving film density and stability. Furthermore, xylose modification significantly reduced the water vapor transmission rate to only 12.64 g/m2·24 h. These modifications significantly enhance the comprehensive properties of SPI films, especially in terms of thermal stability and moisture barrier properties. The correlation analysis between SPI film properties and internal structure shows that glycosylation can change the internal structure of protein and further affect the film properties. The research in this paper provides a theoretical basis for the glycosylation modification of SPI, and provides a new idea for the sustainable development of food packaging materials.

Exploring Camellia oleifera Abel seed cake as sustainable source of protein for food applications: A review

The demand for sustainable plant-based protein is rising due to concerns over the environmental impact of animal-based protein. One promising yet overlooked protein source is the seed cake generated from Camellia oleifera oil extraction (COSC), which contains 14-20 % crude protein. COSC protein (COSCP) exhibit excellent nutritional and functional properties making it a promising ingredient for innovative food products. However, its adoption remains limited. This review discusses COSCP extraction methods, functional properties, and food applications to promote its broader utilization. It also examined how oil extraction methods influence COSCP functional characteristics and explores modification techniques to enhance its functionality. COSCP has excellent functional properties, making it suitable for use as emulsifier, foaming, and gelling agents in food systems. However, cross-linking of COSCP with saponins and phenolics during seed processing compromise the protein yield, purity, and functionality and need to be addressed to fully unlock the potential of COSCP in food applications.

Functional modification of edible film based on egg white protein and its application in food preservation: A review

Based on the urgent need for environmental protection, traditional petroleum-based packaging materials are gradually being replaced by non-toxic and biodegradable biopolymer packaging materials such as proteins, polysaccharides and lipids. Among them, egg white protein (EWP) has been widely concerned because of its excellent gel film forming properties and high nutritional value. EWP film has the advantages of high mechanical strength, good stability, high transparency, controllable cost, good compatibility with human tissue, etc. However, the common problems such as humidity sensitivity and poor flexibility of protein-based films limit its application. In this paper, the characteristics and film-forming mechanism of EWP were introduced, and the film-forming methods, influencing factors, performance improvement (such as physical modification, chemical modification, enzymatic modification and mixing with other functional ingredients, etc.) as well as its application in food packaging were reviewed. In addition, the existing problems and prospects of EWP based films are discussed, which provides a new idea for improving the properties of EWP films and expanding its application in the future.

Effects of whey protein-inulin conjugates with varying degrees of glycosylation on hepatic antioxidant capacity, immunomodulation and gut microbiota in mice

In this study, whey protein isolate-inulin (WPI-In) conjugates with varying degrees of glycosylation (DG) were prepared, characterized, and examined for their potential immunomodulatory effects and regulation of gut microbiota in mice. The data indicated that an increase in DG significantly affects the microstructure and functionalities of WPI-In conjugates. The WPI-In conjugates with high DG promoted the growth and development of the thymus while altering gut microbiota composition by increasing the relative abundance of Bacteroidetes and reducing that of Firmicutes. Additionally, the WPI-In conjugates enhanced liver antioxidant capacity and the secretion of immunoglobulin G, and elevated levels of anti-inflammatory cytokines (IL-4 and IL-2), while decreasing pro-inflammatory cytokine (TNF-α) content in serum. Spearman correlation analysis suggested that the enhancement of liver antioxidant capacity and regulation of immune-related indicators may be associated with the gut microbiota altered by WPI-In conjugates. Therefore, WPI-In conjugates demonstrate beneficial properties, indicating potential applications in food systems.

Unveiling the potential of bean proteins: Extraction methods, functional and structural properties, modification techniques, physiological benefits, and diverse food applications

Bean proteins, known for their sustainability, versatility, and high nutritional value, represent a valuable yet underutilized resource, receiving less industrial attention compared to soy and pea proteins. This review examines the structural and molecular characteristics, functional properties, amino acid composition, nutritional value, antinutritional factors, and digestibility of bean proteins. Their applications in various food systems, including baked goods, juice and milk substitutes, meat alternatives, edible coatings, and 3D printing inks, are discussed. The physiological benefits of bean proteins, such as antidiabetic, cardioprotective, antioxidant, and neuroprotective effects, are also presented, highlighting their potential for promoting well-being. Our review emphasizes the diversity of bean proteins and highlights ultrasound as the most effective extraction method among available techniques. Beyond their physiological benefits, bean proteins significantly enhance the structural, technological, and nutritional properties of food systems. The functionality can be further improved through various modification techniques, thereby expanding their applicability in the food industry. While studies have explored the impact of bean protein structure on their nutritional and functional properties, further research is needed to investigate advanced modification techniques and the structure-function relationship. This will enhance the utilization of bean proteins in innovative and sustainable food applications.

Mechanism studies of gliadin-glucose glycation reaction and products formation by heat treatment with different conduction modes

Heat treatments induce protein-reducing sugar glycation reactions easily, leading to protein structural transformations and advanced glycation end products generation. In this study, effects of four heat conduction modes (air, contact, vapour and liquid-conduction) on the spatial conformation and glycation products of gliadin-glucose system were evaluated. The results showed that gliadin tertiary structure expanded and exposed more hydrophobic sites in vapour-conduction, resulting in more glycation sites. Conversely, air-conduction promoted the protein folded, causing a lighter glycation degree and lower glyoxal, methylglyoxal, acrylamide, 5-hydroxymethylfurfural and carboxymethyl lysine contents (following vapour-conduction > contact-conduction > liquid-conduction > air-conduction). The above phenomena were attributed to the different water content in the different conduction modes. Furthermore, the glycation sites identified in vapour-conduction and contact-conduction were approximately two-fold of that in air-conduction. Conclusively, gliadin-glucose systems subjected to air-conduction showed less glycated intensity and hazardous products.

Carvacrol-loaded emulsions stabilized by soy protein isolate/chitosan oligosaccharide conjugates improved the quality of refrigerated sea bass (Lateolabrax maculatus)

In this study, the soybean protein isolate / chitosan oligosaccharide (SPI/COS) conjugates were developed using glycosylation and used as a stabilizer of carvacrol-loaded emulsions for refrigerating sea bass (Lateolabrax maculatus). The results of Fourier transform infrared spectroscopy and fluorescence spectroscopy showed that COS modified the secondary and tertiary structure of SPI by covalent binding. The SPI/COS conjugate with a mass ratio of SPI and COS of 4:1 (SPI/COS-4) exhibited high glycosylation degree, great water solubility and better emulsification properties. Carvacrol-loaded emulsion stabilized by the SPI/COS-4 (CE-SPI/COS-4) had nanoscale droplet size and remained stable during 40 days of storage. SPI/COS-4 aqueous solution (SPI/COS) and CE-SPI/COS-4 aqueous solution (CE-SPI/COS) in the form of immersion were applied to investigate their preservation effects on sea bass, with sterile water as control check (CK). Sea bass were stored at 4 °C and quality assessments of fish were performed periodically for up to 21 days, which included microbiological and physicochemical analysis. As suggested by microbiological analysis, CE-SPI/COS treatment could significantly inhibit the bacterial growth. The low total volatile basic nitrogen value, thiobarbituric acid value and K-value indicated that CE-SPI/COS greatly retarded protein and lipid oxidation in fish and significantly suppress the degradation of nucleotide. Moreover, fish treated with CE-SPI/COS had minimal color variation and water loss, and maintained hardness, adhesiveness, chewiness, and resilience of fish to the highest degree. Therefore, emulsions stabilized with SPI/COS conjugates may be employed as a potential strategy for the quality maintenance of sea bass.

Effects of Maillard Reaction Durations on the Physicochemical and Emulsifying Properties of Chickpea Protein Isolate

This study investigated the physicochemical and emulsifying properties of chickpea protein isolate (CPI)-citrus pectin (CP) conjugates formed via the Maillard reaction across varying reaction durations. CPI and CP were conjugated under controlled dry-heating conditions, and the resulting conjugates were characterized by measuring their particle size, zeta potential, solubility, thermal stability, surface hydrophobicity, and emulsifying properties. The results showed that as reaction duration increased, the particle size and zeta potential of the CPI-CP conjugates increased significantly, reaching a maximum particle size of 1311.33 nm and a zeta potential of -35.67 mV at 12 h. Moreover, the Maillard reaction improved the solubility, thermal stability, and hydrophobicity of the CPI. Glycosylation increased the emulsifying activity index (EAI) and emulsifying stability index (ESI) of the CPI to 145.33 m2/g and 174.51 min, respectively. Optimal emulsions were achieved at a protein concentration of 1.5 wt% and a 10% volume fraction of the oil phase. The Maillard reaction promoted the interfacial protein content and the thickness of the interfacial layer while decreasing the droplet size and zeta potential of the emulsion. Additionally, the emulsion prepared with CPI-CP-12 h showed outstanding long-term stability. These results demonstrate that a moderate Maillard reaction with CP effectively enhances the physicochemical and emulsifying characteristics of CPI.

A comprehensive review of effects of ultrasound pretreatment on processing technologies for food allergens: Allergenicity, nutritional value, and technofunctional properties and safety assessment

Many proteins are essential food components but also major allergens. Reducing protein allergenicity while preserving its nutritional value and technofunctional properties has always been the goal of the food industry. Ultrasound (US) is a green processing method for modifying proteins. In addition, US pretreatment combined with other processing techniques (USPCT) has been increasingly used in the food industry. Therefore, this review presents an overview of recent advances in the impact of US and USPCT (US-combined enzymatic hydrolysis [USCE], US-combined glycation [USCG], and US-combined polyphenol conjugation [USCP]) on the allergenicity, nutritional value, and technofunctional properties of food allergens. We discuss the potential mechanisms, advantages, and limitations of these technologies for improving the properties of proteins and analyze their safety, challenges, and corresponding solutions. It was found that USPCT can improve the efficiency and effectiveness of different methods, which in turn can be more effective in reducing protein allergenicity and improving the nutritional value and functional properties of processed products. Future research should start with new processing methods, optimization of process conditions, industrial production, and the use of new research techniques to promote technical progress. This paper is expected to provide reference for the development of high-quality hypoallergenic protein raw materials.

Enhancement of soy protein functionality by conjugation or complexation with polysaccharides or polyphenols: A review

Soy proteins have good nutritional quality and exhibit a range of useful functional attributes, making them a viable option for replacing animal proteins in the development of more sustainable and eco-friendly plant-based food products. Nevertheless, soy proteins are prone to denaturation and/or aggregation under conditions they encounter in some food and beverage products (including certain pH, ionic, and thermal conditions), which adversely impact their functional performance. This problem can often be overcome by covalently (conjugation) or noncovalently (complexation) linking the soy proteins to polysaccharides or polyphenols, thereby expanding their application scope. Compared to soy proteins alone, these conjugates or complexes exhibit enhanced technofunctional performance, including improved solubility, emulsification, foaming, gelling, antimicrobial properties, and antioxidant capacities. Conjugates are typically more stable than complexes, which may be an advantage for some food applications. However, complexes do not require additional regulatory approval, which makes them more suitable for most food applications. This review aims to comprehensively examine the enhancement of soy protein functionality through conjugation or complexation with polysaccharides or polyphenols. The research focuses on how these modifications enhance solubility, emulsification potential, foaming, gelling, and antioxidant properties, reduce the allergenicity of soy proteins, and enable their potential applications in plant-based food development, 3D food printing, fat substitutes, functional food carriers, and hypoallergenic foods.

Catalytic elevation effect of methylglyoxal on invertase and characterization of MGO modification products

Reactive carbonyl species can modify digestive enzymes upon intake due to their electrophilic nature. This study evaluated the effects of methylglyoxal (MGO), glyoxal, acrolein, and formaldehyde on invertase, an enzyme presents in digestive tract. Unexpectedly, MGO enhanced, rather than inhibited, invertase activity. Moreover, MGO counteracted the inhibitory effects of the other three carbonyls on invertase activity. Kinetic analyses revealed that 150 mmolLexp.-1 MGO resulted in a 2-fold increase in the Km and a 3.3-fold increase in Vmax, indicating that MGO increased the turnover rate of sucrose while reducing the substrate binding affinity of invertase. Additionally, MGO induced dynamic quenching of fluorescence, reduced free amino groups, increased hydrophobicity, the content of Amadori products, fluorescent and nonfluorescent AGEs, and amyloid fibrils of invertase. The specific modifications responsible for the elevated activity of MGO on invertase require further investigation.

Structural and functional impacts of glycosylation-induced modifications in rabbit myofibrillar proteins

Rabbit meat, recognized for its nutritional value, is gaining global attention. However, the inferior functional properties of rabbit myofibrillar proteins lead to quality degradation during the production process. Glycosylation represents an effective method for enhancing protein functionality. This study investigated the glycosylation modification of rabbit myofibrillar proteins. The results demonstrated that solubility of glucose-glycosylated products increased by 34 %, while the reduction capacity improved from 0.15 mg/mL to 1.6 mg/mL. The·OH free radical scavenging ability increased from 63.94 % to 94.21 %. β-Glucan-glycosylated products exhibited the highest thermal stability, and their DPPH free radical scavenging rate increased from 19.68 % to 76.21 %. Glycosylation also induced changes in protein conformation, characterized by a 10-30 °C increase in thermal denaturation peak temperature, gradual attenuation of endogenous fluorescence intensity, gradual enhancement of λmax redshift, and a 30-40 % decrease in surface hydrophobicity. Molecular docking simulations revealed that the primary interactions between glucose, lactose, and β-Glucan with myofibrillar proteins involve hydrogen bonds and van der Waals forces. In conclusion, glycosylation can effectively improve the functional properties of proteins, contributing to the development and production of high-quality, stable, and nutritious rabbit meat products.

Carvacrol-loaded nanoemulsions stabilized by soy protein isolate / chitooligosaccharide conjugates inhibited the oxidation and conformational variations of myofibrillar proteins in refrigerated sea bass (Lateolabrax maculatus)

Soy isolate protein / chitooligosaccharide (SPI/COS) glycosylated conjugates was prepared and employed as an emulsifier to stabilize carvacrol-loaded nanoemulsions (CNE-SPI/COS). The effects of CNE-SPI/COS on the oxidation and aggregation of myofibrillar protein (MPs) from sea bass (Lateolabrax maculatus) were investigated. Samples were immersed in sterile water (CK), SPI/COS solution and CNE-SPI/COS solution, respectively, follow by a 15-day refrigerated storage. MPs were extracted from fish fillets at 3-day intervals, then assessed for the oxidation degree and conformational changes in MPs, as well as structural variations in myofibrils. Compared with the CK group, the results obtained from protein oxidation assessment clarified that the oxidation and aggregation of MPs was significantly reduced by the CNE-SPI/COS treatment, as evidenced by the higher total sulfhydryl content and Ca2+-ATPase activity and lower surface hydrophobicity. Conformational analysis of MPs showed that CNE-SPI/COS was effective in maintaining the ordered secondary structure of MPs and reducing the exposure of hydrophobic residues in the hydrophobic core of the tertiary structure. In addition, CNE-SPI/COS was found to be effective in protecting the microstructure of muscle fibers and myofibrils in fish fillets. These results suggest that CNE-SPI/COS can be a promising method to prevent protein oxidation and aggregation in fish.

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.

A Review of Modified Gelatin: Physicochemical Properties, Modification Methods, and Applications in the Food Field

Gelatin is a significant multifunctional biopolymer that is widely utilized as a component in food, pharmaceuticals, and cosmetics. Numerous functional qualities are displayed by gelatin, such as its exceptional film-forming ability, gelling qualities, foaming and emulsifying qualities, biocompatibility and biodegradable qualities. Due to its unique structural, physicochemical, and biochemical characteristics, which enhance nutritional content and health benefits as well as the stability, consistency, and elasticity of food products, gelatin is utilized extensively in the food business. Additionally, gelatin has demonstrated excellent performance in encapsulating, delivering, and releasing active ingredients. Gelatin's various modifications, such as chemical, enzymatic, and physical processes, were analyzed to assess their impact on gelatin structures and characteristics. Hopefully, gelatin will be more widely used in various applications after modification using suitable methods.

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.

Emulsifying properties of egg proteins: Influencing factors, modification techniques, and applications

As an essential food ingredient with good nutritional and functional properties and health benefits, eggs are widely utilized in food formulations. In particular, egg proteins have good emulsification properties and can be commonly used in various food products, such as mayonnaise and baked goods. Egg protein particles can act as stabilizers for Pickering emulsions because they can effectively adsorb at the oil-water interface, reduce interfacial tension, and form a stable physical barrier. Due to their emulsifying properties, biocompatibility, controlled release capabilities, and ability to protect bioactive substances, egg proteins have become ideal carriers for encapsulating and delivering functional substances. The focus of this review is to summarize current advances in using egg proteins as emulsifiers. The effects of influencing factors (temperature, pH, and ionic strength) and various modification methods (physical, chemical, and biological modification) on the emulsifying properties of egg proteins are discussed. In addition, the application of egg proteins as emulsifiers in food products is presented. Through in-depth research on the emulsifying properties of egg proteins, the optimization of their applications in food, biomedical, and other fields can be achieved.

Effect of glycosylation modification on structure and properties of soy protein isolate: A review

Soybean protein isolate (SPI) is a highly functional protein source used in various food applications, such as emulsion, gelatin, and food packaging. However, its commercial application may be limited due to its poor mechanical properties, barrier properties, and high water sensitivity. Studies have shown that modifying SPI through glycosylation can enhance its functional properties and biological activities, resulting in better application performance. This paper reviews the recent studies on glycosylation modification of SPI, including its quantification method, structural improvements, and enhancement of its functional properties, such as solubility, gelation, emulsifying, and foaming. The review also discusses how glycosylation affects the bioactivity of SPI, such as its antioxidant and antibacterial activity. This review aims to provide a reference for further research on glycosylation modification and lay a foundation for applying SPI in various fields.

Property and quality of japonica rice cake prepared with Polygonatum cyrtonema powder

Rice cake is a common traditional food in China. In this study, the effect of Polygonatum cyrtonema (PC) on the qualities and characteristics of rice cake was investigated. The incorporation of PC powder in rice cakes endowed a light-yellow color and increased the water content and water absorption of products. Rheological analysis showed that the rice cake containing PC exhibited weak-gel properties. Additionally, PC (40%) inhibited the rice cake aging and lowered the hardness of rice cakes to 13.86 N after 4 h storage. In vitro starch digestion analysis showed that PC (40%) reduced the digestibility of rice cakes by decreasing the starch hydrolysis rate from 88.70 to 58.95%, displaying a low estimated glycemic index (eGI) of 52.14. The findings mentioned above indicated that the inclusion of PC powder in rice cakes enhanced their characteristics and attributes, which also provided an approach for the development of PC products.

Proteins from Legumes, Cereals, and Pseudo-Cereals: Composition, Modification, Bioactivities, and Applications

This review presents a comprehensive analysis of plant-based proteins from soybeans, pulses, cereals, and pseudo-cereals by examining their structural properties, modification techniques, bioactivities, and applicability in food systems. It addresses the critical need for a proper utilization strategy of proteins from various plant sources amidst the rising environmental footprint of animal protein production. The inherent composition diversity among plant proteins, their nutritional profiles, digestibility, environmental impacts, and consumer acceptance are compared. The innovative modification techniques to enhance the functional properties of plant proteins are also discussed. The review also investigates the bioactive properties of plant proteins, including their antioxidant, antimicrobial, and antitumoral activities, and their role in developing meat analogs, dairy alternatives, baked goods, and 3D-printed foods. It underscores the consideration parameters of using plant proteins as sustainable, nutritious, and functional ingredients and advocates for research to overcome sensory and functional challenges for improved consumer acceptance and marketability.

Molecular modification of low-dissolution soy protein isolates by anionic xanthan gum, neutral guar gum, or neutral konjac glucomannan to improve the protein dissolution and stabilize fish oil emulsion

Herein, the effects of anionic xanthan gum (XG), neutral guar gum (GG), and neutral konjac glucomannan (KGM) on the dissolution, physicochemical properties, and emulsion stabilization ability of soy protein isolate (SPI)-polysaccharide conjugates were studied. The SPI-polysaccharide conjugates had better water dissolution than the insoluble SPI. Compared with SPI, SPI-polysaccharide conjugates had lower β-sheet (39.6 %-56.4 % vs. 47.3 %) and α-helix (13.0 %-13.2 % vs. 22.6 %) percentages, and higher β-turn (23.8 %-26.5 % vs. 11.0 %) percentages. The creaming stability of SPI-polysaccharide conjugate-stabilized fish oil-loaded emulsions mainly depended on polysaccharide type: SPI-XG (Creaming index: 0) > SPI-GG (Creaming index: 8.1 %-21.2 %) > SPI-KGM (18.1 %-40.4 %). In addition, it also depended on the SPI preparation concentrations, glycation times, and glycation pH. The modification by anionic XG induced no obvious emulsion creaming even after 14-day storage, which suggested that anionic polysaccharide might be the best polysaccharide to modify SPI for emulsion stabilization. This work provided useful information to modify insoluble proteins by polysaccharides for potential application.

The effect of sequential extraction on the physicochemical and rheological properties of Naematelia aurantialba polysaccharides

To overcome the difficulty of separation and low rate of extraction caused by highly viscous polysaccharides from Naematelia aurantialba (NA), four N. aurantialba polysaccharides (NAPs) were sequentially extracted using water (enzyme-/ultrasound-assisted extraction), alkali (0.1 mol/L NaOH), and acid (0.1 mol/L HCl), and named E-NAP, U-NAP, Al-NAP, and Ac-NAP. The properties of four NAPs were different. The yields of NAPs were 26.05 % (Ac-NAP) > 20.33 % (Al-NAP) > 17.99 % (U-NAP) > 12.77 % (E-NAP), respectively. The monosaccharide composition of NAPs was composed primarily of mannose, xylose, glucose, glucuronic acid, and galactose. Sequential extraction improved the purity and solubility of NAPs, but decreased the particle size, thermal stability, water retention, and crystallinity. Two polysaccharides, U-NAP and Al-NAP, had a triple helix structure. All the NAPs were pseudoplastic fluids with concentration/frequency-dependent entangled structure. Al-NAP with the highest viscosity exhibited an elastic gel, while Ac-NAP with the lowest viscosity was a viscous gel. The behavior of NAPs differed from that predicted using the Cox-Merz rule, and in particular, E-NAP and U-NAP more significantly deviated from the rule. In this study, four NAPs with different properties were extracted sequentially, which provided a theoretical basis for the down-stream processing with high added-value and utilization of NA and NAP.

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.

N-glycoproteomic profiling reveals structural and functional alterations in yellow primary preserved egg white under saline-alkali treatment

The posttranslational N-glycosylation of food proteins is important to their structure and function. However, the N-glycoproteomics of yellow preserved egg white were rarely reported. This study explored the changes of N-glycoproteome in yellow preserved eggs white after salt and alkali treatment. A total of 213 N-glycosites were identified on 102 glycoproteins, revealing prevalent glycosylation motifs and multiple N-glycosites within proteins. Salt and alkali treatment significantly altered the glycosylation patterns, impacting major proteins differently. GO analysis indicated the roles of differentially expressed glycoproteins in responding to stimuli and biological regulation. KEGG analysis emphasized the importance of salivary secretion pathway in enzyme secretion and peptide generation. Protein domain analysis highlighted the downregulation of Serpin. Protein-protein interaction networks revealed Apolipoprotein B as central players. This study provides essential structural information on the glycosylation modifications of egg white proteins, contributing to our understanding of the mechanisms behind the functional properties of preserved eggs.

Conjugation of Soybean Proteins 7S/11S Isolate with Glucose/Fructose in Gels through Wet-Heating Maillard Reaction

Conjugation with glucose (G) and fructose (F) via the Maillard reaction under the wet-heating condition is a natural and non-toxic method of improving the technological functions of 7S/11S proteins in different kinds of gels. It may be used as an affordable supply of emulsifiers and an excellent encapsulating matrix for gels. This study aimed to create a glucose/fructose-conjugated 7S/11S soy protein via the Maillard reaction. The conjugation was confirmed by determining the SDS-PAGE profile and circular dichroism spectra. In addition, these conjugates were comprehensively characterized in terms of grafting degree, browning degree, sulfhydryl content, surface hydrophobicity (H0), and differential scanning calorimetry (DSC) through various reaction times (0, 24, 48, and 72 h) to evaluate their ability to be used in food gels. The functional characteristics of the 7S/11S isolate-G/F conjugate formed at 70 °C, with a high degree of glycosylation and browning, were superior to those obtained at other reaction times. The SDS-PAGE profile indicated that the conjugation between the 7S and 11S proteins and carbohydrate sources of G and F through the Maillard reaction occurred. Secondary structural results revealed that covalent interactions with G and F affected the secondary structural components of 7S/11S proteins, leading to increased random coils. When exposed to moist heating conditions, G and F have significant potential for protein alteration through the Maillard reaction. The results of this study may provide new insights into protein modification and establish the theoretical basis for the therapeutic application of both G and F conjugation with soy proteins in different food matrixes and gels.

Maillard reaction between high-intensity ultrasound pre-treated pea protein isolate and glucose: Impact of reaction time and pH on the conjugation process and the properties of conjugates

In this study, pea protein isolate was pretreated with high intensity ultrasound (HIUS) at 300 W for 5 min. The Maillard reaction (MR) between the pretreated sample (UPPI) and glucose were performed by heating (80 °C) of their aqueous dispersion at various time (0, 6, 12, 18, and 24 h) and pH (6.0, 8.0, 10.0, and 12.0). According to browning index and glucose depletion, the conjugation between UPPI and glucose through MR was not markedly accelerated compared to PPI. FTIR and intrinsic/extrinsic fluorescence spectroscopy showed that HIUS pretreatment could alter secondary and tertiary structures of PPI. HIUS pretreatment coupled with MR increased hydrophobicity and particle size of UPPI-glucose conjugates. Solubility of UPPI and PPI was improved after MR; but the increment of former was lower than the latter. This study suggests that HIUS pretreatment is an effective method to improve the solubility of PPI regardless of the subsequent MR.

Development of quinoa (Chenopodium quinoa Willd) protein isolate-gum Arabic conjugates via ultrasound-assisted wet heating for spice essential oils emulsification: Effects on water solubility, bioactivity, and sensory stimulation

Quinoa protein isolate-gum Arabic (QPI-GA) conjugates were developed by ultrasound-assisted wet heating to improve the water solubility and bioactivity of spice essential oils (EOs) in this study. The optimal conditions for QPI-GA conjugates preparation were found to be: heating temperature of 72 ℃, ultrasound power of 450 W, and reaction time of 46 min. QPI-GA conjugates displayed significantly higher emulsifying efficiency and stronger tolerance to pH variation, high salt concentration, and storage than raw materials. The emulsifying efficiency of emulsions was also influenced by the pH and viscosity of EOs, zeta potential of the emulsion as well as the relative density and lipid/water partition coefficient (P) of EOs were the possible factors impacting the stability of EO emulsions. The water solubility, antioxidant ability, and antibacterial ability of tested EOs were improved after emulsification. Meanwhile, encapsulation with QPI-GA conjugates played a good effect on reducing the sensory stimulation of EOs.

Nonenzymatic glycation as a tunable technique to modify plant proteins: A comprehensive review on reaction process, mechanism, conjugate structure, and functionality

Plant proteins are expected to become a major protein source to replace currently used animal-derived proteins in the coming years. However, there are always challenges when using these proteins due to their low water solubility induced by the high molecular weight storage proteins. One approach to address this challenge is to modify proteins through Maillard glycation, which involves the reaction between proteins and carbohydrates. In this review, we discuss various chemical methods currently available for determining the indicators of the Maillard reaction in the early stage, including the graft degree of glycation and the available lysine or sugar, which are involved in the very beginning of the reaction. We also provide a detailed description of the most popular methods for determining graft sites and assessing different plant protein structures and functionalities upon non-enzymatic glycation. This review offers valuable insights for researchers and food scientists in order to develop plant-based protein ingredients with improved functionality.

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.

Study on Physicochemical Properties of Food Protein

As the global population continues to grow, the demand for sustainable and nutritious food sources has never been higher [...].

Quantitative N-glycoproteomic analysis of egg yolk powder during thermal processing

The production of egg yolk powder often involves critical processes such as pasteurization and spray drying, however, these thermal processes will inevitably affect the functional properties of egg yolk (especially gelation and emulsification). The aim of this study was to elucidate the mechanism of the effect of pasteurized egg yolk (P-EY) and spray-dried egg yolk (SD-EY) on the functional properties through quantitative N-glycoproteomic. The results showed, compared with fresh egg yolk (F-EY), emulsifying property of mild heat-treated P-EY was slightly reduced while the gelation property did not undergo significant changes, whereas emulsifying activity (EAI) and gelation strength of vigorously heat-treated SD-EY were significantly reduced by 48.72 % and 35.73 %, respectively. During thermal processing in SD-EY, larger aggregate particles (particle size ∼10 um) were formed, and the surface hydrophobicity was reduced (93.0 %) and the zeta potential was enhanced (62.8 %). The results of quantitative N-glycoproteomic showed that 13 N-glycosylated proteins (APOB, vitellogenin, etc.) were down-regulated while only 2 N-glycosylated proteins were up-regulated; 21 N-glycosylation sites were down-regulated and 2 N-glycosylation sites were up-regulated in SD-EY, suggesting that covalent cross-linking of protein N-glycoproteins may have occurred in the process of spray-drying, which altered molecular physicochemical characteristics of the yolk solution that further affecting the processing properties of egg yolk.

Pickering Emulsions Stabilized by Conjugated Zein-Soybean Polysaccharides Nanoparticles: Fabrication, Characterization and Functional Performance

This study aims to fabricate zein-based colloidal nanoparticles, which were used to stabilize Pickering emulsions, by conjugation with soybean polysaccharide (SSPS) through the Maillard reaction. The physicochemical properties of the conjugated particles as well as the physical and oxidative stability of the fabricated Pickering emulsion that utilized conjugated colloidal particles with the volumetric ratio of water and oil at 50:50 were investigated. The grafting degree of zein and SSPS was verified through examination of FT-IR and fluorescence. Moreover, the conjugated Zein/SSPS nanoparticles (ZSP) that were prepared after dry heating for 48-72 h exhibit excellent colloidal stability across a range of pH values (4.0-10.0). Further, the wettability of ZSP decreased based on a contact angle analysis of θ~87°. Confocal laser scanning microscopy (CLSM) images indicated that ZSP particles were located around the oil droplets. Additionally, the ZSP effectively improved the oxidative stability of the Pickering emulsions, as demonstrated by a significant decrease in both peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). The results of this study demonstrate that ZSP represents a promising food-grade Pickering emulsifier, capable of not only stabilizing emulsions but also inhibiting their oil oxidation.

Effects of different high-temperature conduction modes on the ovalbumin-glucose model: AGEs production and regulation of glycated ovalbumin on gut microbiota

Food high-temperature processing frequently induces the production of advanced glycation end products (AGEs) in the food industry. In this study, the effects of three high-temperature conduction modes on the AGEs production derived from ovalbumin (OVA)-glucose model and the regulation of glycated OVA on gut microbiota were investigated. The peak time of OVA shifted maximally from 13.72 to 13.57 due to the rise in molecular weight, confirming successful coupling between OVA and glucose. The inhibition of superheated steam (SS) on AGEs was observed, with the sample treated by SS showing the lowest content among glycated OVA groups. The analysis revealed an increase in AGEs during digestion and a decrease in fermentation, suggesting the release during digestion and the availability by intestinal flora. Furthermore, an expansion of Bifidobacterium and Lactobacillus, and the inhibition of Desulfovibrio and Escherichia-Shigella were observed, indicating the prebiotic activity of glycated OVA and its potential to improve intestinal health. These results provide valuable information for controlling high-temperature processing to inhibit AGEs formation and highlight the positive effects of glycated proteins on intestinal health.

Tyrosine glucosylation of collagen films exploiting Horseradish Peroxidase (HRP)

The development of human tissue models for regenerative medicine and animal-free drug screening requires glycosylated biomaterials such as collagen. An easy and fast biomaterial glycosylation method exploiting Horseradish Peroxidase (HRP) phenol coupling reaction is proposed. The protocol is adaptable to any polymer functionalized with phenol residues or tyrosine containing proteins. As a model the tyrosine residues on collagen films were functionalized with salidroside, a natural β-glucoside with a phenol in the aglycone. Scanning Electron Microscope (SEM) and contact angle analysis revealed the influence of glycosylation on the sample's morphology and wettability. Preliminary biological evaluation showed the cytocompatibility of the glucosylated collagen films.

Comprehensive binding analysis of glycated myosin with furan derivatives via glucose by means of multi-spectroscopy techniques and molecular docking simulation

Myosin is an ideal binding receptor for aroma compounds and its functional properties are easily affected by glucose. The study comprehensively clarified the effects of glucose glycation-induced structural modifications of myosin on its binding ability with furan derivatives, including 2-methylfuran, 2-furfural, and 2-furfurylthiol. The results demonstrated that the binding levels of furan derivatives were obviously affected by the glycation levels of myosin due to the changes of myosin structure and surface. The increased glycation levels caused the unfolding of myosin structure and accelerated the aggregation, as were exhibited by the data of zeta potential, particle size, microstructure, and secondary structure. The glycated myosin with wrinkled surfaces favored the significant increase of hydrophobic interactions (31.59-69.50 μg), the more exposure of amino acid residues (3459-6048), the formation of free sulfhydryl groups (16.37-20.58 mmol/104g) and hydrogen bonds. These key (non)covalent linkages accounted for the generation of glycated myosin-odorants complex, including 2-furfurylthiol (29.17-47.87 %), thus enhancing the resultant binding ability as evidenced by the free furan derivatives concentrations, fluorescence quenching and molecular docking simulation analysis. The glycated myosin for 8 h bound highest concentrations of furan derivatives. The results will provide comprehensive data on the retention of aroma compounds in meat products.

Comparison of ovalbumin glycation induced by high-temperature steaming and high-temperature baking: A study combining conventional spectroscopy with high-resolution mass spectrometry

High-temperature steaming (HTS) and high-temperature baking (HTB)-induced ovalbumin (OVA)-glucose glycation (140 °C, 1-3 min) were compared, and the different mechanisms were evaluated by changes in protein conformation, glycation sites and average degree of substitution per peptide molecule (DSP) values as well as the antioxidant activity of glycated OVA. Conventional spectroscopic results suggested that in comparison with HTB, HTS promoted protein expansion, increased β-sheet content and made OVA structure more orderly. Liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis showed that 10 glycation sites were found under HTB, while 4 new glycation sites R111, R200, R219 and K323 appeared under HTS, and 2 of them (R219 and K323) were located in internal β-sheet chains. The antioxidant activities of glycated OVA increased with increasing treatment time, and HTS showed stronger enhancement effect than HTB. Furthermore, the DSP values were generally higher under HTS than HTB. Compared with HTB, HTS with high penetrability could enhance the change of OVA primary structure and spatial conformation, making the protein structure more unfolded and stable, leading to more protein-sugar collisions occurred in inner OVA molecular and significantly promoted glycation. In conclusion, HTS is a promising method for high-temperature short-time glycation reaction, with drastically increasing the protein antioxidant activities.

Purification, Immunological Identification, and Characterization of the Novel Silkworm Pupae Allergen Bombyx mori Lipoprotein 3 (Bomb m 6)

Allergic reactions caused by silkworm pupae greatly limit their utilization, and studies suggest that silkworm pupae proteins of 25-30 kDa may be the principal allergens. To further understand these allergens, we attempted to purify a protein of about 30 kDa by ammonium sulfate salting, pH-graded precipitation, and ion-exchange chromatography. The protein was identified by mass spectrometry and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), western blot, enzyme-linked immunosorbent assays, circular dichroism, and fluorescence spectroscopy analyses. We identified the purified protein as Bombyx mori lipoprotein 3 (Bmlp3), which has high IgE reactivity and is a novel uncharacterized allergen that we named Bomb m 6 according to the WHO/IUIS Allergen Nomenclature Sub-Committee. This allergen is stable against heat, acids, bases, and digestion. In conclusion, we successfully purified and characterized a novel silkworm pupa allergen, which may inform the diagnosis and treatment of silkworm pupa allergies.

The Nutritional and Functional Properties of Protein Isolates from Defatted Chia Flour Using Different Extraction pH

This study aims to determine the effects of various alkaline pHs on the nutritional and functional properties of protein isolated from defatted chia flour (DCF). The DCF isolated using alkali extraction method at pH 8.5, 10.0, and 12.0 were coded as CPI-8.5, CPI-10.0, and CPI-12.0, respectively. The highest extraction yield and protein recovery yield was demonstrated by CPI-12.0 (19.10 and 59.63%, respectively), with a total protein content of 74.53%, and glutelin showed the highest portion (79.95%). The CPI-12.0 also demonstrated the most elevated essential (36.87%), hydrophobic (33.81%), and aromatic (15.54%) amino acid content among other samples. The DCF exhibited the highest water (23.90 gg-1) and oil (8.23 gg-1) absorption capacity, whereas the CPI-8.5 showed the highest protein solubility (72.31%) at pH 11. DCF demonstrated the highest emulsifying capacity at pH 11 (82.13%), but the highest stability was shown at pH 5 (82.05%). Furthermore, CPI-12.0 at pH 11 shows the highest foaming capacity (83.16%) and stability (83.10%). Despite that, the CPI-10.0 manifested the highest antioxidant capacity (DPPH: 42.48%; ABTS: 66.23%; FRAP: 0.19), as well as ACE-I (35.67%). Overall, the extraction pH had significant effects in producing chia protein isolates (CPI) with improved nutritional and functional qualities.

Modified Structural and Functional Properties of Fish Gelatin by Glycosylation with Galacto-Oligosaccharides

This study aimed to investigate the effects of galacto-oligogalactose (GOS) glycosylation on the structural and functional properties of fish gelatin (FG). Results showed that with the increase of glycosylation time, grafting degree and browning increased, and new protein bands with increased molecular weight were observed by SDS-PAGE. Structural analysis showed that glycosylation reduced intrinsic fluorescence intensity and increased surface hydrophobicity of FG. FTIR analysis showed α-helix content decreased while random coil content increased in glycosylated FG. Emulsion activity index and emulsion stability index along with foam activity and foam stability were significantly elevated in GOS-4 and GOS-8, but FG glycosylated longer than 12 h exhibited less pronounced improvement. Glycosylated FG showed lower gel strength than control. The results indicate that moderate glycosylation could be applied to improve interfacial properties of FG.

A comprehensive review of mung bean proteins: Extraction, characterization, biological potential, techno-functional properties, modifications, and applications

The popularity of plant-based proteins has increased, and mung bean protein (MBP) has gained immense attention due to its high yield, nutritional value, and health benefits. MBP is rich in lysine and has a highly digestible indispensable amino acid score. Dry and wet extractions are used to extract MBP flours and concentrates/isolates, respectively. To enhance the quality of commercial MBP flours, further research is needed to refine the purity of MBPs using dry extraction methods. Furthermore, MBP possesses various biological potential and techno-functional properties, but its use in food systems is limited by some poor functionalities, such as solubility. Physical, biological, and chemical technologies have been used to improve the techno-functional properties of MBP, which has expanded its applications in traditional foods and novel fields, such as microencapsulation, three-dimensional printing, meat analogs, and protein-based films. However, study on each modification technique remains inadequate. Future research should prioritize exploring the impact of these modifications on the biological potential of MBP and its internal mechanisms of action. This review aims to provide ideas and references for future research and the development of MBP processing technology.

Behavior of protein-polysaccharide conjugate-stabilized food emulsions under various destabilization conditions

The sensitivity of protein-stabilized emulsions to flocculation, coalescence, and phase separation under destabilization conditions (i.e., heating, aging, pH, ionic strength, and freeze-thawing) may limit the widespread use of proteins as effective emulsifiers. Therefore, there is a great interest in modulating and improving the technological functionality of food proteins by conjugating them with polysaccharides, through the Maillard reaction. The present review article highlights the current approaches of protein-polysaccharide conjugate formation, their interfacial properties, and the behavior of protein-polysaccharide conjugate stabilized emulsions under various destabilization conditions, including long-term storage, heating and freeze-thawing treatments, acidic conditions, high ionic strength, and oxidation. Protein-polysaccharide conjugates are capable of forming a thick and cohesive macromolecular layer around oil droplets in food emulsions and stabilizing them against flocculation and coalescence under unfavorable conditions, through steric and electrostatic repulsion. The protein-polysaccharide conjugates could be therefore industrially used to design emulsion-based functional foods with high physicochemical stability.

Glycosylation modification: A promising strategy for regulating the functionalities of myofibrillar proteins

Myofibrillar proteins (MPs), the most important proteins in muscle, play a vital role in the texture, flavor, sensory and consumer acceptance of final muscle-based food products. Over the past several decades, conjugation of carbohydrates to MPs via glycosylation is of particular interest due to the substantial enhancement in MPs characteristics. Studying the covalent interactions between carbohydrates and MPs under various processing conditions and molecular mechanisms by which carbohydrates affect the functionalities of MPs can introduce new perspectives for design and production of muscle-based foods. However, there is no insightful and comprehensive summary of the structural, physicochemical and functional characteristics changes of MPs induced by glycosylation modification and how these changes can be adopted to potentially promote the science-based development of tailor-made muscle foods. Based on this, the functionalities of MPs as well as their practical limiting issues are initially highlighted. A comprehensive overview of fabrication strategies is then introduced. Additionally, changes in the structural and functional properties of MPs regulated by glycosylation have also been carefully summarized. On this basis, the research limitations to be solved and our perspectives for the future development of muscle-based foods are put forward.

Effects of glycation methods on the interfacial behavior and emulsifying performance of soy protein isolate-gum Arabic conjugates

Glycated conjugation of plant protein such as soy protein isolate (SPI) with saccharides is one popular strategy to modify the physicochemical characteristics of these plant protein resources, which may be affected by the glycation methods including dry-heating and wet-heating. In this study, the impact of these two glycation methods on the rheological and emulsifying properties of a binary system made by SPI-gum Arabic (GA) was studied. The results indicated that dry-heating conjugates had higher viscosity and more elastic characteristics than those wet-heating conjugates. The emulsifying properties of SPI-GA conjugates by different preparation routes were evaluated by various oil phases including eugenol, cinnamaldehyde and soybean oil. Overall, emulsions stabilized by dry-heating conjugates showed lower zeta-potential value than those with wet heating conjugates. The interfacial properties of these conjugates were compared using soybean oil emulsion as a model. Higher emulsifying ability and stability were obtained by emulsions with dry-heating conjugates, which was attributed to their more compact structures, higher protein adsorption capacity and thicker viscoelastic films formed at the interface, and therefore enhanced electrostatic repulsion between droplets. The findings in this study are useful for fabrication and utilization of protein-polysaccharide glycation conjugates as emulsifiers in functional foods.

Novel Colloidal Food Ingredients: Protein Complexes and Conjugates

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

Sequential administration of virus-like particle-based nanomedicine to elicit enhanced tumor chemotherapy

Protein cages have played a long-standing role in biomedicine applications, especially in tumor chemotherapy. Among protein cages, virus like particles (VLPs) have received attention for their potential applications in vaccine development and targeted drug delivery. However, most of the existing protein-based platform technologies are plagued with immunological problems that may limit their systemic delivery efficiency as drug carriers. Here, we show that using immune-orthogonal protein cages sequentially and modifying the dominant loop epitope can circumvent adaptive immune responses and enable effective drug delivery using repeated dosing. We genetically modified three different hepadnavirus core protein derived VLPs as delivery vectors for doxorubicin (DOX). These engineered VLPs have similar assembly characteristics, particle sizes, and immunological properties. Our results indicated that there was negligible antibody cross-reactivity in either direction between these three RGD-VLPs in mice that were previously immunized against HBc VLPs. Moreover, the sequential administration of multiple RGD-VLP-based nanomedicine (DOX@RGD-VLPs) could effectively reduce immune clearance and inhibited tumor growth. Hence, this study could provide an attractive protein cage-based platform for therapeutic drug delivery.

Hepatic parenchymal cell and mitochondrial-targeted astaxanthin nanocarriers for relief of high fat diet-induced nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a metabolic syndrome disorder. Here, hepatic parenchymal cell and mitochondrial-targeted nanocarriers were constructed to deliver astaxanthin (AST) to liver tissue to maximize AST intervention efficiency. The hepatic parenchymal cell-targeting was achieved using galactose (Gal) conjugated onto whey protein isolate (WPI) through the Maillard reaction by recognizing asialoglycoprotein receptors specifically expressed in hepatocytes. Grafting triphenylphosphonium (TPP) onto glycosylated WPI by an amidation reaction enabled the nanocarriers (AST@TPP-WPI-Gal) to achieve dual targeting capability. The AST@TPP-WPI-Gal nanocarriers could target mitochondria in steatotic HepG2 cells with an enhanced anti-oxidative and anti-adipogenesis effect. The ability of AST@TPP-WPI-Gal to target liver tissue was verified by an NAFLD mice model, and the results showed that AST@TPP-WPI-Gal could regulate blood lipid disorders, protect liver function, and remarkably reduce liver lipid accumulation (40%) compared with that of free AST. Therefore, AST@TPP-WPI-Gal might have potential as a dual targeting hepatic agent for nutritional intervention for NAFLD.