Insights into the Binding Mechanism of Polyphenols and Fish Myofibrillar Proteins Explored Using Multi-spectroscopic Methods

Plasma-activated water in combination with coconut exocarp flavonoids emerge as promising preservation technique for golden pompano: Impact of the treatment sequence

In the current study, the preservation effect of plasma-activated water (PAW), coconut exocarp flavonoids (CF) and their combination on golden pompano fillets during refrigerated storage was investigated with emphasize on the treating sequence. PAW effectively inactivated spoilage bacteria and inhibited total volatile basic nitrogen (TVB-N) increase, while boosted the TBARS and carbonyl values. PAW+CF exerted synergistic effect on extending the period before total bacterial count and TVB-N content reaching acceptance limit than PAW or CF alone (P < 0.05). In addition, their combined treatment effectively reduced fillets discoloration and texture deterioration. Simultaneously, lipid and protein oxidation were significantly inhibited, which was comparable to CF. It was indicated that the treatment sequence of PAW and CF profoundly impact the preservation effect. Specifically, prior CF marinating followed by PAW was more effective than the opposite sequence. Thus, combination of CF followed by PAW served as promising technique for fish fillets preservation.

Effect of L-cysteine on the physicochemical properties of heat-induced sheep plasma protein gels

The effects of different l-Cysteine additions (0-2 %) on the gel properties, microstructure and physicochemical stability of sheep plasma protein gels were studied. The introduction of l-Cys significantly improved the water retention capacity and whiteness of the plasma protein gel (p < 0.05). The addition of 0.2 %-0.4 % l-Cys increased gel strength, but l-Cys had no significant effect on gel elasticity (p < 0.05). Scanning electron microscopy confirmed that the addition of l-Cys also promoted the formation of a porous three-dimensional network structure in the gel. Raman spectroscopy and SDS-PAGE revealed that the addition of l-Cys generally reduced α-helix structures in protein gels and promoted the formation of β-folds. Addition of 0.2 % l-Cys treatment leading to the greatest increase in disulfide bonds, and its surface hydrophobicity and endogenous fluorescence intensity were the largest. At this time, the comprehensive performance of sheep plasma protein gel is the best performance.

Recent advances and challenges in the interaction between myofibrillar proteins and flavor substances

Myofibrillar proteins are an important component of proteins. Flavor characteristics are the key attributes of food quality. The ability of proteins to bind flavor is one of their most fundamental functional properties. The dynamic balance of release and retention of volatile flavor compounds in protein-containing systems largely affects the sensory quality and consumer acceptability of foods. At present, research on flavor mainly focuses on the formation mechanism of flavor components, while there are few reports on the release and perception of flavor components. This review introduces the composition and structure of myofibrillar proteins, the classification of flavor substances, the physical binding and chemical adsorption of myofibrillar proteins and volatile flavor substances, as well as clarifies the regulation law of flavor substances from the viewpoint of endogenous flavor characteristics and exogenous environment factors, to provide a theoretical reference for the flavor regulation of meat products.

Effect mechanism of capsaicin and dihydrocapsaicin in chili on the oxidative stability of myoglobin in duck meat

BACKGROUND

Myoglobin (Mb) in duck meat is commonly over-oxidized when heated at high temperatures, which may worsen the color of the meat. Enhancing the oxidative stability of Mb is essential for improving the color of duck meat. Capsaicin and dihydrocapsaicin (CA-DI) in chili exhibit antioxidant properties. This study investigated the effects of CA-DI on the structure and oxidative damage of Mb by fluorescence spectroscopy, differential scanning calorimetry analysis and particle size in duck meat during heat treatment.

RESULTS

When the ratio of CA-DI to Mb was 10:1 g kg-1 and heat-treated for 36 min, oxymyoglobin significantly increased, and metmyoglobin significantly decreased compared with the control group (P < 0.05). In parallel, the carbonyl content of Mb in the CA-DI group decreased by 43.40 ± 0.10%, the sulfhydryl content increased by 188 ± 0.21%, and the free radical scavenging activity of Mb was significantly enhanced (P < 0.05). Moreover, the addition of CA-DI resulted in a significant decrease in the particle size of the Mb surface (P < 0.05). When the ratio of CA-DI to Mb was 10:1 g kg-1, CA-DI enhanced the thermal stability and significantly increased the thermal denaturation temperature of Mb. The molecular docking results indicated that hydrophobic interactions and hydrogen bonds were involved in the binding of CA-DI to Mb.

CONCLUSION

CA-DI could combine with Mb and improve the oxidation stability of Mb in duck meat. This suggested that CA-DI could be a potential natural antioxidant that improves the color of meat products. © 2024 Society of Chemical Industry.

A comprehensive investigation on the interaction between jaceosidin, baicalein and lipoxygenase: Multi-spectroscopic analysis and computational study

Lipoxygenase (LOX) has the harmful effect of accelerating lipid oxidation, and polyphenols have the inhibitory effect on lipoxygenase. However, there were rare researches investigated on the interactions between polyphenols and LOX. In this study, the binding mechanisms between polyphenols (Jaceosidin-JSD and baicalein-BCL) and LOX were investigated by multi-spectroscopic analysis and computational study. Both JSD and BCL binding to LOX resulted in static fluorescence quenching, and the complexes of JSD-LOX and BCL-LOX were built at a molar ratio of 1:1, respectively. The binding constants of LOX-JSD (72.18 × 105 L/mol at 298 K) and LOX-BCL (12.43 × 105 L/mol at 298 K) indicated that LOX had stronger binding affinity to JSD compared to BCL. Compared with BCL-LOX, the JSD-LOX system formed more hydrogen bonds which ensured a stronger bond between JSD and LOX. The studies in molecular dynamics also demonstrated that the JSD-LOX complex is more stable, and the addition of JSD is more conducive to the complex formation. The current study provides some new insights for the study on the inhibition of lipid oxidation and affords a new strategy for the discovery of novel food preservatives.

Effect of Fenugreek (Trigonella foenum-graecum L.) Seed Extracts on the Structure of Myofibrillar Protein Oxidation in Duck Meat

The effect of fenugreek (Trigonella foenum-graecum L.) seed extracts (FSEs) on the structure of duck myofibrillar protein (MP) oxidation was researched via particle size, zeta potential, Fourier transform infrared (FTIR), fluorescence spectroscopy, SDS-PAGE, and scanning electron microscopy (SEM) in the Fenton oxidation system. FSE (0.3 mg/mL) could scavenge 58.79% of the hydroxyl radical and possessed good antioxidation. FSE could retard the oxidation of MP, and the carbonyl formation and total sulfhydryl loss of MP decreased by 42.00% and 105.94%, respectively, after 4.67% of FSE treatment. SDS-PAGE results showed that 0.67% and 2.67% of FSE decreased the strength of the myosin heavy chain (MHC) and actin bands of the oxidized MP, respectively. The FSE changed the secondary structures of the MP and promoted the unfolding of the MP structure and the transformation from α-helix to β-turn. When treated with 0.67% of FSE, the hydrophobicity of the MP declined by 26.14%, and solubility was improved by 37.21% compared with the oxidation group. After 0.67% of FSE treatment, the particle size and zeta potential of the MP returned to the level of the blank group. Scanning electron microscopy revealed that FSE improved the apparent morphology of the MP. Overall, FSE had positive effects on the antioxidation of the duck MP, and it could improve the structure and characteristics of the MP. It is hoped that FSE could be considered as a natural antioxidant to retard the oxidation of the MP in meat products.

Effect of Capsaicin and Dihydrocapsaicin in Capsicum on Myofibrillar Protein in Duck Meat

Spice and its extracts have gained widespread utilization as natural and eco-friendly additives, imparting enhancements in flavor, color, and antioxidative attributes to meat-based products. This work aims to study the effect mechanism of capsaicin (CA) and dihydrocapsaicin (DI) in capsicum (chili pepper) on the structure and function of myofibrillar proteins (MPs) in duck meat during thermal treatment. The results showed that at a CA-DI to MP ratio of 1:500 (g/g) following a 12 min heat treatment, the carbonyl content of MPs in duck meat decreased by 48.30%, and the sulfhydryl content increased by 53.42%. When the concentration was 1:500 (CA-DI, g/g) after 24 min of heat treatment, the •OH and DPPH radical scavenging rates were highest at 59.5% and 94.0%, respectively. And the initial denaturation temperature of MPs was the highest at 96.62 °C, and the thermal absorption was lowest at 200.24 J g-1. At the parameter, the smallest particle size and size distribution range of MP were 190 nm (9.51%). Furthermore, the interplay between CA-DI and MPs contributed to a reduction in the protein particle size and intrinsic fluorescence. In summary, the combination of CA-DI and MPs played a crucial role in inducing protein unfolding and disintegration.

Modification of the Structural and Functional Characteristics of Mung Bean Globin Polyphenol Complexes: Exploration under Heat Treatment Conditions

During the storage and processing of mung beans, proteins and polyphenols are highly susceptible to interactions with each other. Using globulin extracted from mung beans as the raw material, the study combined it with ferulic acid (FA; phenolic acid) and vitexin (flavonoid). Physical and chemical indicators were combined with spectroscopy and kinetic methods, relying on SPSS and peak fit data to statistically analyze the conformational and antioxidant activity changes of mung bean globulin and two polyphenol complexes before and after heat treatment and clarify the differences and the interaction mechanism between globulin and the two polyphenols. The results showed that, with the increase in polyphenol concentration, the antioxidant activity of the two compounds increased significantly. In addition, the antioxidant activity of the mung bean globulin-FA complex was stronger. However, after heat treatment, the antioxidant activity of the two compounds decreased significantly. The interaction mechanism of the mung bean globulin-FA/vitexin complex was static quenching, and heat treatment accelerated the occurrence of the quenching phenomenon. Mung bean globulin and two polyphenols were combined through a hydrophobic interaction. However, after heat treatment, the binding mode with vitexin changed to an electrostatic interaction. The infrared characteristic absorption peaks of the two compounds shifted to different degrees, and new peaks appeared in the areas of 827 cm^-1, 1332 cm^-1, and 812 cm^-1. Following the interaction between mung bean globulin and FA/vitexin, the particle size decreased, the absolute value of zeta potential increased, and the surface hydrophobicity decreased. After heat treatment, the particle size and zeta potential of the two composites decreased significantly, and the surface hydrophobicity and stability increased significantly. The antioxidation and thermal stability of the mung bean globulin-FA were better than those of the mung bean globulin-vitexin complex. This study aimed to provide a theoretical reference for the protein-polyphenol interaction mechanism and a theoretical basis for the research and development of mung bean functional foods.

Analysis of inhibition of guava (Psidium guajava l.) leaf polyphenol on the protein oxidative aggregation of frozen chicken meatballs based on structural changes

This study compared the effects of guava leaf polyphenol (GLP) on the aggregation and structural changes of myofibrillar proteins (MPs) from chicken meatballs, frozen for 6 months, with that of tea polyphenol (TP). The high antioxidation ability of 450 mg/L GLP was manifested by changes in 1, 1-diphenyl-2-picrylhydrazyl (DDPH), 2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, and the ferric reducing antioxidant power (FRAP) in vitro. Compared with the control, the carbonyl, disulfide bond content, particle size, zeta potential and turbidity of sample with GLP decreased by 25.9 %, 17.7 %, 18.2 %, 11.4 % and 11.7 %, respectively, while the solubility of the sample, after freezing it for 6 months, increased by 14.8 %. Meanwhile, in sustaining the structural stability of MPs, the GLP-treated group exhibited better microstructure (scanning electron microscopy, SEM), lower free amino and sulfhydryl loss, higher α-helix structure and fluorescence intensity than the control. Our results showed that GLP significantly inhibited MP aggregation, and was superior to TP in terms of its particle size, solubility, and turbidity, sulfhydryl content (P < 0.05). Overall, it was demonstrated that GLP has the potential to inhibit protein aggregation and enhance structural stability during frozen storage.

Hydrophobic bonds-dominated key off-odors/silver carp myofibrillar protein interactions, and their binding characteristics at cold storage and oral temperatures

•

Off-odors binding to MP via hydrophobic forces is a spontaneous process.

•

Nonanal had the strongest binding ability to MP among the three off-odors.

•

MD method provided a structural basis for the fluorescence spectroscopic analysis.

•

Three off-odors, especially nonanal, could change the conformation of MP.

•

Compared with others, nonanal formed more binding sites to Trp residues in Myosin1.

This study revealed the interaction mechanism between silver carp myofibrillar protein (MP) and key off-odors by combining fluorescence spectroscopy with molecular dynamics (MD) simulation. Spectroscopic results exhibited a dynamic quenching mechanism between MP and off-odors. Thermodynamic analysis indicated that the MP/off-odors interaction was spontaneous (ΔG° < 0) and dominated by hydrophobic interactions (ΔH° > 0, ΔS° > 0). Meanwhile, the binding affinity was in the order of nonanal (n = 1.38) > hexanal (n = 0.89) > 1-octen-3-ol (n = 0.65), which was further verified by the MD results. Among off-odors, nonanal had the highest binding energy with myosin (8105.66 kJ/mol) and formed more hydrophobic binding sites to Trp residues in myosin head (e.g., Trp820 and Trp822), thereby changing myosin conformations via both physical and chemical interactions. Additionally, higher binding energies of myosin/off-odors were observed at oral temperature (37 °C) than at cold storage temperature (4 °C), implying that less off-odors were released at 37 °C.

Explore the Interaction between Ellagic Acid and Zein Using Multi-Spectroscopy Analysis and Molecular Docking

With the increasing interest in value-added maize products, the interaction of zein with bioactive molecules to become more nutritional and beneficial to human health has gained a lot of attention. To broaden the application of ellagic acid (EA) in maize flour products, we investigated the interaction between zein and EA. The fluorescence quenching type of zein interacting with EA was mainly static quenching through hydrophobic interaction, as demonstrated by quenching behavior modeling, and ultraviolet-visible spectroscopy confirmed the formation of zein–EA complexes. Synchronous fluorescence spectroscopy showed that EA reduced the polarity of zein around tyrosine residues, which were exposed to a more hydrophobic microenvironment. Meanwhile, circular dichroism suggested that EA noticeably changed the secondary structure of zein, which was mainly reflected in the increase of α-helix and β-sheet content and the decrease of random coil content. Finally, the molecular docking simulation found that zein could have five active sites binding to EA and there was hydrogen bond interaction besides hydrophobic interaction. The findings of this study provided a basis for a theory for the interaction mechanism between zein and EA, which could be essential for developing value-added plant-derived protein products using EA as a functional component.

Structural and functional modifications of myofibrillar protein by natural phenolic compounds and their application in pork meatball

Effects of different phenolic compounds on the structural and functional properties of myofibrillar protein (MP) were investigated, and the phenolic compounds were applied as natural modifiers in pork meatball. Interactions between MP and phenolic compounds were determined via molecular docking to elucidate the modification mechanisms. Tannic acid, gallic acid, (-)-epigallocatechin gallate, and epigallocatechin interacted with MP primarily through hydrogen bonds, which unfolded the secondary structures of MP and lowered surface hydrophobicity. Accordingly, the solubility, gel properties, and oxidation stability of MP were improved, while the emulsifying properties significantly decreased. Quercetin and quercitrin showed electrostatic interactions with MP, which preserved α-helix structures and increased surface hydrophobicity. While, the modifications lent MP the enhanced emulsifying properties, thermal stability, and oxidation stability, but the gel properties and solubility were mitigated. In addition, the incorporation of phenolic compounds prevented MP oxidation based upon their antioxidant abilities deriving from hydroxyl groups. Once the phenolic compounds were used in pork meatball, a minced meat model, they significantly improved the quality of meatball by bettering the texture properties and controlling the oxidation level. The results suggest that phenolic compounds have great potential to be employed as natural additives in minced meat products for the modification of functional properties.

Development and characterization of fish myofibrillar protein/chitosan/rosemary extract composite edible films and the improvement of lipid oxidation stability during the grass carp fillets storage

Biofilm composition from fish myofibrillar protein (FMP) and chitosan solution (CS) incorporated with rosemary extract (RE) was developed and applied to monitor the freshness of fish fillets. The effects of different concentrations of RE as well as physical, mechanical, structural and functional properties of FMP/CS films were investigated. Films containing RE showed reduced water solubility and water vapor permeability and enhanced tensile strength and elongation at break. Results also showed good compatibility of the components and good dispersion of RE in the matrix. However, the content of RE (0.2%, v/v) added in the composite films produced aggregations and had negative effects on their film-forming properties. The antioxidant capacity of composite films was related to the level of RE and demonstrated by the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging assay. Chilled grass carp fillets wrapped with different films to evaluate the preservative effect. Results of thiobarbituric acid reactive substances, pH value, Free amino acid and total volatile basic nitrogen indicated that FMP/CS/RE composite film could protect the fish fillet well and inhibit the lipid oxidation. The developed FMP/CS/RE composite films possess the potential to be applied as edible films in the food packaging industry and food cold chain transportation.

Use of Spectroscopic Techniques to Monitor Changes in Food Quality during Application of Natural Preservatives: A Review

Consumer demand for food of high quality has driven research for alternative methods of food preservation on the one hand, and the development of new and rapid quality assessment techniques on the other hand. Recently, there has been a growing need and interest in healthier food products, which has led to an increased interest in natural preservatives, such as essential oils, plant extracts, and edible films and coatings. Several studies have shown the potential of using biopreservation, natural antimicrobials, and antioxidant agents in place of other processing and preservation techniques (e.g., thermal and non-thermal treatments, freezing, or synthetic chemicals). Changes in food quality induced by the application of natural preservatives have been commonly evaluated using a range of traditional methods, including microbiology, sensory, and physicochemical measurements. Several spectroscopic techniques have been proposed as promising alternatives to the traditional time-consuming and destructive methods. This review will provide an overview of recent studies and highlight the potential of spectroscopic techniques to evaluate quality changes in food products following the application of natural preservatives.