Monosaccharide-induced glycation enhances gelation and physicochemical properties of myofibrillar protein from oyster (Crassostrea gigas)

Combining soy protein isolate and sorbitol as cryoprotectants for portuguese oysters (Crassostrea angulata) and investigating the effect on ice crystal damage

Freezing and thawing often cause significant damage to the muscle tissue of seafood products, reducing their quality and shelf life. This study investigated the combined effects of soy protein isolate (SPI) and sorbitol (So) to mitigate freezing damage in portuguese oysters. A single-factor analysis was performed to determine the optimal concentrations of SPI (1 %-9 %), So (1 %-9 %), and soaking times (30-90 min) based on the steaming loss. An orthogonal experimental design further assessed the combined effects of these factors. The results demonstrated that the combination of 6.0 % SPI and 4.0 % So reduced steaming loss by 10 % and oxidative damage by 0.17 mg MDA/kg. It minimized ice crystal formation in oyster muscle tissue, reduced Ca2+-ATPase inactivation, and decreased total sulfhydryl group loss. These findings indicate that the SPI-So composite effectively preserves the structural and functional properties of frozen oysters, offering a promising natural cryoprotectant for the seafood industry.

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.

Effect of xylose glycation and ultrasonication on the interfacial properties and physicochemical stability of silkworm pupa protein-stabilized Pickering emulsion and its applicability in emulsion-filled hydrogels

Silkworm pupa protein isolate (SPPI) has the potential of being used (as an alternative nutrient) in various food products, but it has poor emulsifying and gelling property. In this study, SPPI was modified by glycation and/or ultrasonication, and the interfacial properties and stability of Pickering emulsions stabilized by SPPI-xylose conjugates and their application in emulsion-filled hydrogels (EFHGs) were investigated. Results showed that, compared with the control, the contact angle of glycated SPPI (using 3 % xylose under ultrasonication, US-X3%) decreased from 144.6° to 110.9°, and the penetration and rearrangement rates at the water-oil interface increased by 20.76 % and 72.11 %, respectively. Pickering emulsion stabilized by US-X3% exhibited smaller droplet size, stronger electrostatic repulsion and interfacial pressure, thicker interfacial film, as well as higher elasticity-dominated viscoelastic behavior. After combined treatment, the -20 °C and - 80 °C freeze-thaw stability of SPPI emulsion was increased by 3.78 and 1.62 times, respectively, and the thermal, refrigeration and salt stability were also significantly improved (p < 0.05). By filling the conjugate-stabilized Pickering emulsion (US-X3%), the content of hydrogen and ionic bonds in EFHGs network was decreased, the hardness and chewiness of the hydrogels were reduced, and the water holding capacity was increased to 95.75 %. The results of gastrointestinal digestion (in vitro) showed that the addition of xylose and the use of sonication had no significant effect on the protein digestibility of EFHGs (p > 0.05). Thus, SPPI-xylose conjugates prepared by glycation and ultrasonication exhibited excellent application potential in emulsion/gel hybrid food system.

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.

Glycation-induced gel and digestive properties for 3D printing and conventional gels of myofibrillar protein from oyster (Crassostrea gigas)

Glycation has great potential to enhance protein gel properties. The purpose was to investigate the glycation of oyster myofibrillar protein (MP) with monosaccharides (glucose [Glu]) and oligosaccharides (dextran 5 [Dex5]) combined with scallop columns for 3D printing and conventional gels to elucidate the differences in gel properties (texture characteristics, water-holding capacity, cooking yield, cooking loss, thermal characteristic, and water distribution) and digestive properties (in vitro digestibility, degree of hydrolysis, and molecular weight distribution) between the two gels. The results demonstrated that Glu-modified oyster MP had the best gel and digestive properties. The digestibility in vitro of MP-Glu modified 3D printing and conventional gels increased by 17.1% and 11.88%, while the degree of hydrolysis increased by 12.19% and 10.62%, respectively. Hydrogen and disulfide bonds were determined to be the main intermolecular forces maintaining the protein gels, and all prepared gels conformed to the transitional foods in the International Dysphagia Diet Standardization Initiative (IDDSI). In vitro digestibility was significantly positively correlated with gel hardness, degree of hydrolysis, L*, ΔE*, WHC and cooking loss. This study could fully utilize the potential advantages of glycation modification and 3D printing technology, aiming to provide theoretical support for the development of shellfish 3D printing products with personalized needs for people with dysphagia.

Structural and gel property changes in chicken myofibrillar protein induced by argon cold plasma-activated water: With a molecular docking perspective

This study investigated the effects of plasma-activated water (PAW) generated with argon at discharge times of 0, 4, 8, 12, and 16 min on the gel properties and structures of chicken myofibrillar protein (MP). Under treatments of 8, 12, and 16 min, both the gel strength and water retention capacity of MP significantly improved, with the gel strength (0.53 N) peaking at 16 min and the lowest cooking loss（30.38 %）. As the treatment time increased from 0 to 16 min, the storage modulus also gradually increased. Results from low-field nuclear magnetic resonance indicated a slowing of water proton mobility, with the proportion of bound water rising from 0.26 % (0 min) to 0.52 % at 16 min. Fourier transform infrared spectroscopy, endogenous fluorescence spectroscopy and scanning electron microscopy confirmed PAW's alteration of MP's secondary and tertiary structures and gel microstructure. Additionally, this study explored the influence of argon PAW's primary active species on MP from a molecular docking perspective·H2O2 could form hydrogen bonds with MP, while O3 and NO2‾could interact via both hydrogen bonds and electrostatic interactions. Thus, PAW can alter protein structure and enhance MP's functional properties, providing insights for applying cold plasma in processing chicken gel products.

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.

Molecular structural modification of myofibrillar protein from oyster (Crassostrea gigas) with oligosaccharides for improving its gel properties

Glycation is a promising approach to enhance protein gel characteristics in the food industry. The impact of oyster myofibrillar protein (MP) being glycosylated with six oligosaccharides (dextran [Dex]-1 kDa, 5 kDa, 6 kDa, and 10 kDa, xylan [Xyla], and xyloglucan [Xyg]) on structural properties, aggregation behavior and gel properties was investigated in this study. The findings demonstrated that oligosaccharides significantly increased the glycation degree of MP by forming a stable tertiary conformation, increasing the contents of the disulfide bond and hydrogen bonds. Additionally, particle sizes decreased and solubility increased after glycation, improving the gel's strength, water-holding capacity, thermal stability, elastic modulus, and ordered network layout. It was determined that MP-Dex 5 had the best gel properties. The gel strength and water holding capacity of MP-Dex 5 increased by 70.59% and 32.27%, respectively. Molecular dynamics simulations results showed van der Waals energy and electrostatic interactions favor myosin binding to Dex or Xyla units. This study will provide insights into the relationship between molecular structure, aggregation behavior and gel property of oyster MP-oligosaccharide couples, and expand the application of oyster MP in food gels.

Cyclic Continuous Glycation Enhanced Dispersibility of Myofibrillar Protein: Reaction Efficiency and Sites Modification

Reaction efficiency in glycation lacks sufficient attention, leading to the waste of process costs. Cyclic continuous glycation (CCG) is an effective approach to accelerate covalent binding between myofibrillar protein (MP) and glucose. This study elucidated that CCG promoted the exposure of reactive glycated sites in MP with full unfolding of secondary and tertiary structures. Notably, the glycation rate was significantly increased by 65.43%. Physicochemical properties indicated that MP-glucose conjugates with high graft degree exhibited favorable solubility, dispersibility, and thermal stability. Furthermore, proteomics was applied to reveal the glycated sites and products in glycoconjugates of MP. Glycation preferentially acted on the tails of the myosin heavy chain. The glucosylation modification on the head region was enhanced by CCG contributing to the inhibition of the head-head interaction. Overall, this study systematically clarifies the mechanism of CCG, providing a theoretical basis for the application of glycation in innovative meat products.

Integrated ultra-high pressure and salt addition to improve the in vitro digestibility of myofibrillar proteins from scallop mantle (Patinopecten yessoensis)

Myofibrillar protein (MP) is susceptible to the effect of ionic strength and ultra-high pressure (UHP) treatment, respectively. However, the impact of UHP combined with ionic strength on the structure and in vitro digestibility of MP from scallop mantle (Patinopecten yessoensis) is not yet clear. Therefore, it is particularly important to analyze the structural properties and enhance the in vitro digestibility of MP by NaCl and UHP treatment. The findings demonstrated that as ionic strength increased, the α-helix and β-sheet gradually transformed into β-turn and random coil. The decrease of endogenous fluorescence intensity indicated the formation of a more stable tertiary structure. Additionally, the exposure of internal sulfhydryl groups increased the amount of total sulfhydryl content, and reactive sulfhydryl groups gradually transformed into disulfide bonds. Moreover, it reduces aggregation through increased solubility, decreased turbidity, particle sizes, and a relatively dense and uniform microstructure. When MP from the scallop mantle was treated with 0.5 mol/L ionic strength and 200 MPa UHP treatment, it had the highest solubility (90.75 ± 0.13%) and the lowest turbidity (0.41 ± 0.03). The scallop mantle MP with NaCl of 0.3 mol/L and UHP treatment had optimal in vitro digestibility (95.14 ± 2.01%). The findings may offer a fresh perspectives for developing functional foods for patients with dyspepsia and a theoretical foundation for the comprehensive utilization of scallop mantle by-products with low concentrations of NaCl.

An unfolding/aggregation kinetic instructed rational design towards improving graft degree of glycation for myofibrillar protein

Glycation is an effective strategy for the application of myofibrillar protein (MP) in beverage formulas by improving water solubility. In conventional glycation, the efficiency was limited as MP-saccharides conjugates mostly produced at low temperature due to thermosensitivity. This study was aimed to explore unfolding/aggregation kinetics of MP, including aggregate behavior, structural characteristics, and micromorphology, which guided the selection of temperature for glycation. It was shown that 40 °C/47.5 °C were critical temperature for MP unfolding/aggregation, respectively. Accordingly, an innovative technology of glycation (cyclic continuous glycation, CCG) was established by combining such temperatures. The results confirmed that cyclic continuous heating (CCH) inhibited excessive exposure of sulfhydryl and hydrophobic groups impeding protein aggregation. Importantly, it was revealed that rational designed CCG promoted covalent binding of MP to glucose by regulating unfolding-aggregation balance, exhibiting higher glycation degree. Overall, CCG-modified MP is expected to motivate the application of meat proteins in food formulations.

Mechanism for improving the in vitro digestive properties of coconut milk by modifying the structure and properties of coconut proteins with monosodium glutamate

In this paper, the effect of monosodium glutamate (MSG) on coconut protein (CP) solubility, surface hydrophobicity, emulsification activity, ultraviolet spectroscopy and fluorescence spectroscopy was investigated. Meanwhile, the changes in the in vitro digestive properties of coconut milk were also further analyzed. MSG treatment altered the solubility and surface hydrophobicity of CP, thereby improving protein digestibility. Molecular docking showed that CP bound to pepsin and trypsin mainly through hydrogen bonds and salt bridges. And MSG increased the cleavable sites of pepsin and trypsin on CP, thus further improving the protein digestibility. In addition, MSG increased the Na+ concentration in coconut milk, promoted flocculation and aggregation between coconut milk droplets, which prevented the binding of lipase and oil droplets and inhibited lipid digestion. These findings may provide new ideas and insights to improve the digestive properties of plant-based milk.

Improvement in the gelling properties of myofibrillar protein from the razor clam (Sinonovacula constricta) through phosphorylation and structural characterization of the modified protein

This study investigated the modification of myofibrillar protein (MP) from the razor clam through phosphorylation by using various phosphate salts, namely, sodium tripolyphosphate (STPP), sodium trimetaphosphate (STMP), sodium polyphosphate (STTP) and sodium pyrophosphate (TSPP), and their mechanisms of action for functional and gelling properties. Fourier transform infrared spectrometry (FTIR) showed that MP introduced phosphate groups during phosphorylation; these phosphates changed the secondary structure. Moreover, MP after phosphorylation led to an increase in solubility, which was more evident in the case of TSPP phosphorylation, leading to the improvement of gel properties. Therefore, TSPP was the phosphate with the best gel properties in the modification of MP, showing the highest phosphorus content, which resulted in better gelling properties owing to its relatively shorter chains. These results showed that phosphate was able to improve protein cross-linking through ion interactions and electrostatic interactions, which ultimately improved the gelling properties of the razor clam protein.