Effects of high pressure modification on conformation and gelation properties of myofibrillar protein

Exploring the off-flavour removal mechanism of d-limonene, geraniol and acetophenone in perilla leaves from the perspective of molecular structure and kinetic properties

Perilla leaf can effectively remove off-flavours from meat cuisine, but its mechanism of action is still unclear. The effects of three characteristic aroma-active compounds (CAACs) on the structure of myofibrillar proteins (MPs) were studied. The interactions between CAACs, off-flavour compounds (OFCs) and MPs were explored. CAAC can reduce the adsorption of OFCs on MPs. Under the action of CAAC, the α-helix structure content of MPs decreased, and the content of random coil structure increased, resulting in the aggregation of MPs, which enhanced the exposure of negative charges on the surface of MPs and the zeta potential decreased from 4.52 mV to 7.5 mV. At this time, the binding interaction between OFCs and MPs weakened, resulting in the extrusion of OFCs. Fluorescence spectroscopy analysis found that the fluorescence signal of MPs was quenched after the addition of CAAC, and the connection between CAAC and MP was mainly through hydrophobic interaction. Molecular dynamics simulation showed that the average binding energy of geraniol was -7.69644 kcal/mol, which was stronger than the average binding energy of hexanal to protein (-4.67025 kcal/mol). Some binding sites on MPs partially overlapped with hexanal, and hexanal that originally bound to MPs were replaced by CAAC. In summary, CAAC molecules compete with hexanal for binding sites by changing the conformation of MPs, thereby reducing the binding rate of hexanal. This study provides new ideas for studying the off-flavour removal mechanism of spices.

Effect of ultra-high pressure combined with heat-assisted treatment on the characterization, moisture absorption, and antioxidant activity properties of walnut peptide

In this study, ultra-high pressure (UHP) and heat-assisted technology (HT) were used to process walnut peptides (WP) and investigate their combined effects (UHP-HT) on the characterization, moisture absorption, and antioxidant activity of WP. The results indicated that UHP (300 Mpa, 10 min) combined with HT treatment (55 °C, 30 min) significantly increased the surface hydrophobicity and disulfide bonds of WP. UHP-HT-treated WP exhibited lower moisture absorption and more stable water molecule migration. Additionally, the moisture absorption capacity of the WP (48.78 %) was significantly decreased in WP-UHP, WP-HT and WP-UHP (45.37 %, 43.15 %, and 40.19 %, respectively) because of increasing the surface hydrophobicity. UHP-HT combined improved structural characteristics, including particle size, zeta potential, and functional group stability, and significantly enhanced the antioxidant activity of WP under high humidity conditions. Overall, these findings suggest that UHP-HT can effectively reduce the moisture absorption of WP, thus enhancing its storage stability and extending its shelf life.

3D printing of starch-lipid-protein ternary gel system: The role played by protein

This study investigated the printability of a typical food ternary (starch-lipid-protein) gel system and revealed the critical role of protein. The results revealed that a higher content of α-helix and a lower content of random coil in proteins positively impacted the printing accuracy of the ternary gel system. Higher α-helix content in proteins increased the shear rate at the nozzle, ensuring smooth extrusion during 3D printing while also reducing the gel velocity and filament expansion, which led to smoother filament surfaces. Moreover, higher α-helix content and lower random coil content in proteins increased V-type crystalline structures, average molecular size (Rh), and amylose (AM) chains with 100 < X ≤ 1000, while decreasing amylopectin (AP) chains with 6 < X ≤ 12 in starch. These multi-scale structural changes increased A23 content, leading to an increase in the storage modulus of the gel system and improving the mechanical property of 3D printed products, ultimately enhancing printing accuracy.

Modifying yellowfin tuna myofibrillar proteins under ultra-high pressure auxiliary heat treatment: Impact on the conformation, gel properties and digestive characteristics

This study investigated the changes in physicochemical and functional properties of yellowfin tuna myofibrillar protein (MP) under various ultra-high pressure (UHP) auxiliary heat methods. The UHP-assisted heat treatment induced a rearrangement of the MP secondary structure, facilitating the formation of MP gel networks and resulting in higher storage modulus (G') values. Microstructure results revealed that MP gel produced with UHP auxiliary heat exhibited a more rigid network. As pressure increased, the regular aggregation of protein molecules enhanced the stability and water-binding capacity within the gel network, particularly under the two-stage UHP auxiliary heat (TUH) condition at 300 MPa. MP gel prepared under this condition exhibited a 1.95-fold increase in gel strength compared to the control group and the lowest creep strain. Furthermore, in vitro simulated digestion results indicated that TUH method significantly improved the digestive properties of MP gel, suggesting potential for the development of easily digestible MP-based gel foods.

Effect of pre-freezing and accelerated thawing on frozen egg yolk gelation behavior revealing the molecular mechanism

BACKGROUD

Freezing is a commonly used method to prolong the storage duration of egg yolk, which induces irreversible gelation after being stored below -6 °C. The present study examined the effects of pre-freezing and thawing conditions on the gelation of egg yolk liquid, accessing its rheological properties, molecular structure and water mobility.

RESULTS

The results indicated that pre-freezing at -40 °C for 7 days followed by storage at -18 °C was a cost-effective method, with the consistency coefficient being decreased by approximately 30% compared to that of egg yolk liquid frozen directly at -18 °C. Pre-freezing was beneficial in generating smaller ice crystals, preventing the protein denaturation and aggregation caused by mechanical damage from larger ice crystals, and reducing the loss of protein molecular bound water. On the other hand, thawing in a 50 °C water bath was found to be the most effective method. The consistency coefficient of egg yolk liquid pre-freezed at -40 °C for 3 days and then thawed at 50 °C decreased by 73% compared to the sample directly frozen at -18 °C and then thawed at room temperature. The increase in fluidity of egg yolk after freezing was related to protection of bonding water and less cross-linking, as verified by the higher content of β-sheet and smaller particle size.

CONCLUSION

The pre-freezing process promoted the formation of a greater number of small ice crystals, which mitigated the mechanical damage to proteins and the consequent denaturation and aggregation. Additionally, thawing at elevated temperatures could effectively avoid recrystallization, protecting proteins from denaturation and aggregation, leading to a further reduction in gel strength and an increase in fluidity. The findings of the present study contribute to a better understanding of the factors influencing egg yolk gelation and offer insights into the development of enhanced freezing and thawing techniques for egg yolk. © 2025 Society of Chemical Industry.

Environmental factors and blueberry anthocyanin-induced conformational changes modulate the interaction between myofibrillar proteins and fishy compounds and their mechanism, specifically aldehydes and alcohols

This study investigated the impact of blueberry anthocyanin (BA) on the interaction between tilapia myofibrillar protein (MP) and fishy compounds (hexanal, octanal, nonanal, trans-2-nonenal, and 1-octen-3-ol). Results indicated that at a protein concentration of 5 mg/mL and fishy compounds at 5 μg/mL, MP effectively adsorbed these compounds at 4 °C, pH 7.0, and 0.6 mol/L Na+. Increasing BA concentration (0.03-0.24 mg/mL) enhanced the α-helix content of MP from 30 % to 60 %, with a blue shift in the maximum fluorescence emission peak (333-337 nm), suggesting that BA promotes protein structural folding and stability. In MP and fresh fish models, BA addition significantly decreased hexanal (from 50.2 % ± 1.6 % to 29.0 % ± 9.5 %), octanal (from 97.8 % ± 1.6 % to 38.7 % ± 1.8 %), and nonanal (from 69.4 % ± 7.7 % to 39.0 %). Conversely, higher BA concentrations led to increased release of 1-octene-3-ol (from 104.1 % ± 4.4 % to 120.4 % ± 1.1 %). Overall, the findings highlight the correlation between BA's effects on protein folding and stabilization and its influence on the controlled release of fishy compounds, underscoring the significance of polyphenols in protein-flavor interactions. This research offers valuable insights into flavor management and establishes a theoretical basis for flavor regulation in tilapia meat products, contributing to the broader study of quality control and flavor enhancement in meat products through natural pigment active ingredients.

A new method and mechanism for the rapid detoxification of the herb Pinelliae Rhizoma from the Araceae family, based on the dual destruction of raphides and lectin proteins

Pinelliae Rhizoma (PR), a traditional herbal medicine and dietary supplement, is valued for its cough relief and anti-inflammatory effects. However, it can cause significant throat irritation. And unfortunately, current processing techniques can lead to a considerable loss of active constituents in PR. This study employed microwave irradiation to process PR and elucidated the mechanisms underlying its attenuation of PR's irritation. The results demonstrated that microwave irradiation significantly enhanced the processing efficiency, reducing the traditional processing cycle from 5 to 15 days to just 10 min, while preserving active ingredients and mitigating irritation. Subsequent analysis of the irritant components found that microwave treatment significantly reduced the raphides content, altering their morphology. Concurrently, the secondary structure of lectin proteins underwent significant changes, including an increase in β-sheets, a decrease in β-turns and random coils content, and the formation of insoluble aggregates. In conclusion, microwave irradiation is an effective method for reducing the irritation of PR, with the mechanism attributed to the physical destruction of raphides and alterations in the hydrophobicity of lectin proteins. This study provides a novel approach and method for the processing and development of Araceae herbs, as well as food products such as yam, konjac, and pineapple.

High-pressure processing enhances konjac glucomannan/zeaxanthin complex interactions: Implications for colorful plant-based gels

This study investigates the effects of high-pressure processing (HPP) on the physicochemical and structural properties of konjac glucomannan (KGM)/zeaxanthin (ZEA) composite-colored gel. Gels treated with varying pressures and holding times were analyzed, with untreated samples serving as the control. The results indicate that HPP at 300 MPa for 15 min significantly improved pigment retention and water-holding capacity by 14.58 % and 1.02 %, respectively, while also enhancing gel hardness and chewiness. Structural analysis revealed that HPP increased enthalpy change (ΔH) and relative crystallinity by 44.83 % and 20.32 %, respectively, contributing to improved thermal stability. Spectroscopic analysis further confirmed that HPP strengthened hydrophobic and hydrogen bonding interactions within the complex, leading to the formation of a denser three-dimensional network structure. These findings highlight the potential of HPP as an effective approach to improve the stability and functionality of plant-based colored gels, providing valuable insights for the development of functional konjac gel products.

Effects of ultrasound-induced structural modifications on the emulsifying properties of Tenebrio molitor proteins

Ultrasonication has emerged as a promising technique for modifying physicochemical properties of proteins, enhancing their functionality in food applications. This study evaluated the effects of ultrasonic treatment on the structural and functional properties of mealworm-derived proteins (MPs) and their potential as emulsifiers. Dynamic light scattering revealed a significant reduction in MP particle size from 3464.3 nm (untreated) to 115.5 nm (30 min sonication), along with increased zeta potential, indicating improved colloidal stability. Sonication enhanced oil-holding capacity and solubility, suggesting improved interfacial adsorption and emulsification. Circular dichroism and FT-IR spectroscopy confirmed structural modifications, including increased α-helix content and enhanced hydrogen bonding interactions. Free sulfhydryl content and surface hydrophobicity analyses indicated ultrasound-induced unfolding, exposing functional groups that contribute to emulsifying properties. Sonicated MPs demonstrated superior emulsion stability under varying temperature, pH, and ionic conditions. Furthermore, digestibility analysis showed improved gastric digestion (72.7 % to 82.8 %) and enhanced lipid digestion in the small intestine (36.2 % to 47.9 %), suggesting greater bioavailability. These physicochemical modifications highlight the feasibility of using sonicated MP as natural emulsifiers with enhanced functionality. This study underscores their potential in food formulations, particularly for nutritionally fortified emulsions, contributing to sustainable and functional food ingredient development.

Alkali-Induced Hydrolysis Facilitates the Encapsulation of Curcumin by Fish (Cyprinus carpio L.) Scale Gelatin

Curcumin-loaded alkali-induced fish scale gelatin (AFSG) was fabricated to evaluate its efficacy as a potential carrier for hydrophobic nutrients. In this study, the effect of the alkali hydrolysis period on the AFSG hydrolysate structure and corresponding curcumin loading efficiency have been elucidated. Results showed that alkali-induced degradation of gelatin yields different polymers with molecular weights (Mw) from 19319 to 3881 Da. Moderate alkali hydrolysis of fish scale gelatin exposes hydrophobic amino acids, enhancing hydrophobic interactions and increasing the proportion of these amino acids. This process also promotes a structural shift, favoring β-sheet formation while reducing α-helix content. Moreover, the curcumin loading efficiency of AFSG (2 h) (10.06 ± 0.27 μg/mL) was significantly higher than that of untreated gelatin (2.16 ± 0.39 μg/mL), while its excessive hydrolysis weakens hydrophobic interactions among hydrophobic amino acids, limiting their binding sites for curcumin. Fluorescence spectroscopy indicated that curcumin-induced fluorescence quenching in AFSG follows a static mechanism. Thus, the above results demonstrated AFSG's potential as an effective carrier for lipophilic nutrients with high encapsulation efficiency.

Tracking nutritional and quality changes in frozen pork: A 12-month study using 7 categories of meat parameters and VIS/NIR spectroscopy

Frozen pork stocks are critical for stabilizing food security and prices, but assessing nutritional and physicochemical changes during freezing remains challenging. This study conducted a 12-month frozen storage experiment at -20 °C on 50 pigs' longissimus muscles, quantifying changes in 62 meat quality components in 7 categories, including thawing loss, myoglobin, fatty acids, amino acids, and deterioration indicators. The Prophet model suggests pork retains good quality for 1-2 years under proper freezing, with significant deterioration appearing after 4 years. Phenotypic correlations across dimensions reveal key interactions and abnormalities, such as arachidonic acid (C20:4n6) and methionine (Met) deviating from their respective clusters. Using VIS/NIRS and nine machine learning algorithms, a storage time classification model achieved 85.8 % accuracy with SpecimIQ transmission spectra and AdaBoost. These findings demonstrate the potential of VIS/NIRS in food safety and processing, providing a practical solution for precise storage duration identification and valuable insights for managing frozen pork reserves.

Mechanism of enhanced quality of Acetes chinensis powder-Alaska Pollock surimi: Gel properties, rheological properties, micro-structure

To enhance the gel properties of Alaskan pollock surimi, the Acetes chinensis powder (ACP) with different contents (0.5-3 % w/w) was added to the surimi and its mechanisms were investigated. Results showed that adding 1.5 % ACP increased gel strength to 4198.47 g·cm, improved textural properties and storage modulus (G'), as well as reduced free water and drip loss by 49.7 % and 36.7 %, respectively. Moreover, secondary structure analysis showed a 33.5 % increase in β-sheet and a 34.7 % decrease in random coil, reflecting a more organized protein structure. This is associated with a 195.6 % increase in endogenous glutaminase activity and a 14.7 % increase in facilitated cross-linking of MHC heavy chains. ACP also promoted the unfolding of protein and the exposing of more sulfhydryl groups that converted into disulfide bonds (increased by 4.8 %). These resulted in a more compact protein structure, denser microstructure, and homogeneous gel network. In conclusion, 1.5 % ACP effectively improves surimi gel properties, offering valuable insights for optimizing thermal gelation.

Effects of nanocellulose combined with high pressure on the textural, structural, and gel properties of Nemipterus virgatus sausage

This study aimed to improve the gel quality of golden threadfin bream (Nemipterus virgatus) sausage by adding sugarcane nanocellulose (SNC) and using high pressure combined with a two-stage heat treatment. The gel strength, textural properties, protein secondary structure, water states, and microstructure were analyzed and compared. The results indicated that the heat treatment was beneficial to stabilizing the protein gel structure, increasing the gel strength and textural quality, and reducing the cooking loss. High-pressure treatment resulted in a decrease of α-helix and an increase of β-sheet in the protein, forming a dense gel structure, which enhanced the gel strength and the percentage of bound water. The superior hydrophilicity of nanocellulose and its cross-linking with protein increased the percentage of bound water in the gel, which improved the water-holding capacity and mechanical properties. Therefore, the best gel quality was obtained by adding nanocellulose and treating it with high pressure combined with two-stage heating.

Enhancing the gelation properties by synergistic interplay between eel myofibrillar protein and egg white protein

This study investigated the effects of different concentrations of egg white protein (EWP) on the formation and properties of MP-EWP composite gels, systematically analyzing their structural changes, molecular interactions and gel network. Fourier transform infrared spectroscopy and intrinsic fluorescence spectroscopy revealed that moderate EWP addition (1.5 %) facilitated the unfolding of MP molecules, inducing conformational changes that exposed hydrophobic groups and sulfhydryl sites. The intermolecular force analysis showed that EWP addition primarily enhanced the hydrophobic interactions and disulfide bond formation, stabilizing the gel three-dimensional matrix. The composite gels formed at 1.5 % EWP exhibited peak storage modulus (G'), reflecting the optimal gel elasticity and structural integrity. Additionally, the composite gel achieved a water-holding capacity of 89.14 % and a gel strength of 4.9 N × mm, along with a dense and homogeneous gel network with reduced pore size. However, excessive EWP (>1.5 %) led to large aggregates accompanied with enhanced phase separation and disrupted gel uniformity, as evidenced by the increase in free water content observed through low-field nuclear magnetic resonance. These findings offer valuable insights into the role of EWP in modulating MP-EWP gel formation and properties, providing practical guidance for developing high-quality eel-based gel products.

Effects of plasma-activated water on structural and functional properties of PSE-like chicken protein isolate

Pale, soft and exudative (PSE)-like chicken meat is rich in high-quality proteins, however, due to the properties of PSE-like meat, the functional characteristics of PSE-like chicken meat protein isolate (PPI) are affected. The present investigation aimed to improve the functional properties of PPI by employing plasma activation water (PAW), with the ultimate goal of enhancing its utility in various applications. The effects of PAW on the structure and function of PPI were evaluated. PAW treatment induced the protein structure to change from random coil to α-helix, which made the protein conformation more stable. PAW caused the hydrophobic residues to be exposed, thereby effectively enhancing their surface hydrophobicity. Dynamic rheology revealed the storage modulus of PPI gradually raised with increasing of PAW activation time. The scanning electron microscopy (SEM) showed that PAW promoted PPI to form a rough surface. When PAW activation time increased to 40 s, the foaming ability of PPI was raised by 77.84%, the emulsifying activity index was increased to 20.94 m2/g, the emulsion stability index was improved by 20.40%, and the in vitro digestibility was increased by 25.15% (P < 0.05). The above results showed PAW could modify the structural properties, and effectively improve the emulsifying and foaming properties of PPI, and increase the in vitro digestibility of PPI.

Characteristics of exopolysaccharides - egg white protein composite gel and its application in low - fat sausage

A composite gel was developed by integrating antioxidant extracellular polysaccharides (EPS) derived from Pediococcus acidilactici S1 with egg white protein (EWP), aiming to evaluate its potential as a viable alternative to animal fat in pork sausages. The results indicated that the EPS - EWP gel exhibited a lower free water content, an enhanced water - holding capacity, a higher apparent viscosity, and increased storage and loss modulus. Molecular interactions were strengthened, resulting in a more stable structure characterized by the transition of secondary structure from random coils to ordered β - sheets. Molecular docking (MD) analysis revealed favorable binding conformations and strong binding energies between ovalbumin (OVA) and EPS, particularly through the formation of specific pockets involving interactions with residues such as Lysine (Lys) and Aspartic acid (Asp). Hydrophobic and electrostatic forces were identified as the primary driving forces for this energetic combination. Additionally, low - fat sausages showed a significant 32.87 % improvement in inhibiting fat oxidation.

Thermorheological properties and structural characteristics of soy and pumpkin seed protein blends for high-moisture meat analogs

This study explored the effects of soy protein isolate (SPI) and pumpkin seed protein concentrate (PSC) blends on the thermorheological properties and microstructure of high-moisture meat analogs. Using a Discovery Hybrid Rheometer, we observed that increasing PSC content weakened SPI network formation, resulting in decreased gel stability and a more porous, less aligned structure. Microstructural analyses (FE-SEM and FT-IR) revealed a correlation between protein network disruption and increased PSC content. Additionally, higher PSC levels reduced overall bonding (ionic, hydrogen, hydrophobic, disulfide), modifying the texture and softening the gel while retaining solid-like characteristics essential for replicating meat textures. Although full high-moisture extrusion conditions were not replicated, the observed trends offer valuable insights into texture development for meat substitutes. Future research using a closed-system rheometer is required to validate these findings and improve precision.

Inhibitory effect of L-arginine on the oxidative aggregation behavior of myofibrillar proteins in the Antarctic krill (Euphausia superba): pH and antioxidation

In this study, the effect of L-arginine (L-Arg) on the oxidative aggregation of myofibrillar proteins (MPs) in Antarctic krill was evaluated. The results showed that the oxidized aggregation of MPs was significantly inhibited after the addition of 20 mM L-Arg compared to the oxidized group, the solubility of MPs significantly increased by 25.74 %, the turbidity reduced from 0.56 to 0.18. These effects were primarily attributed to the addition of L-Arg, which prevented the unfolding of the spatial structure of MPs after oxidation, inhibited the formation of disulfide bonds and dityrosine, and improved the stability of MPs structure. Analysis of carbonyl content and hydroxyl radical (•OH) inhibitory capacity showed that carbonyl formation and hydroxyl radicals were effectively reduced by the pH and guanidinium group of L-Arg. The pH of L-Arg exhibited a significantly higher effect than the guanidinium group in inhibiting the oxidative aggregation of MPs.

Effects of ultrahigh pressure heat-assisted technology on the physicochemical and gelling properties of myofibrillar protein from Penaeus vannamei

This study investigated the changes in conformation and gelling properties of myofibrillar protein (MP) from Penaeus vannamei under various ultrahigh pressure (UHP)-heat assisted technologies. The results indicated that UHP heat-assisted technology enhanced the cross-linking of the gel network by causing a rearrangement of the secondary structure of MP. Microstructural analysis revealed that MP gels treated with UHP heat-assisted technology exhibited a more uniform gel network structure. Additionally, UHP heat-assisted technology improved the binding capacity of water molecules within the gel network, particularly in the two-stage UHP heat-assisted (PBH) condition at 400 MPa. Gels prepared under this condition demonstrated the highest gel strength, measuring 386.4 g·mm. Furthermore, in vitro simulated digestion showed that PBH method significantly improved the digestibility of MP gels, suggesting that the UHP heat-assisted technology had the potential to produce easily digestible MP gel-based aquatic foods.

Effect of different thermal processing methods and thermal core temperatures on the protein structure and in vitro digestive characteristics of beef

This study aimed to investigate the effect of different thermal processing treatments on the protein digestion characteristics of beef. The beef samples were subjected to different cooking methods, namely steaming, boiling, and roasting, and different core temperatures (75 °C, 80 °C, 85 °C, and 90 °C), and were subjected to in vitro gastrointestinal digestion simulation. All the thermal processing treatments increased the protein digestibility; the samples that were steamed at 85 °C (S85), boiled at 80 °C (B80), and roasted at 80 °C (R80) showed the biggest gains. The S85 released more peptide species after gastrointestinal digestion, according to peptididomic studies. These differences were closely related to protein structure. Thermal processing treatments resulted in a higher degree of proteolysis and looser protein conformation, as evidenced by decreased intrinsic fluorescence and electrophoretic band intensity, increased surface hydrophobicity, and the change in protein secondary structure from α-helix to β-sheet and random coil. Based on the results, S85 was identified as the optimal thermal processing treatment for enhancing the digestibility of beef protein. The results provide valuable insights into the nutritional qualities and digestion of heat-processed beef protein.

Mechanistic insights into the interaction of Lycium barbarum polysaccharide with whey protein isolate: Functional and structural characterization

Protein-polysaccharide interactions are crucial for food system structure and stability. This study investigates the interaction of Lycium barbarum polysaccharide (LBP) at 0-2.00 % concentrations with whey protein isolate (WPI), focusing on functionality and structural changes. LBP covalently grafted onto WPI, as confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), forming WPI-LBP complexes with a maximum degree of grafting (DG) of 44.58 % at 2.00 % LBP. This grafting reduced WPI's surface hydrophobicity (H0) and improved solubility, emulsifying properties, and digestibility under certain conditions, with optimal antioxidant activity at 1.00 % LBP. Multispectral analysis and microscopy showed LBP grafting alters WPI's secondary, tertiary, crystalline, and micro/nanostructures. The comprehensive analysis indicates that the interaction between LBP and WPI involves covalent bonding, hydrogen bonding, hydrophobic interactions, and electrostatic forces, as supported by zeta potential and chemical forces results. These findings suggest LBP-protein complexes as promising food materials for enhancing functionality and stability in the food industry.

Studies of the binding mechanism between liquid smoke from tea tree branches and proteins in dry-cured tenderloin using 4D-DIA proteomics, synergistic multispectral analysis, and molecular docking techniques

This research investigates the impact of various concentrations of tea branch liquid smoke (TLS) on the protein structure of dry cured pork tenderloin using multispectral techniques, molecular docking, and 4D-DIA proteomics. The results reveal that TLS enhances the solubility of myofibrillar protein, with varying effects on tryptophan exposure based on the concentration. Notably, at 5 mL/kg, TLS inhibits myofibrillar protein unfolding. Raman spectroscopy demonstrates that higher TLS concentrations mitigate disruptions in hydrogen bonding and hydrophobicity. Guaiacol and furfural in TLS engage in π-stacking interactions with myosin, heightening myosin interaction with its carrier. 4D-DIA proteomics has revealed that TLS can down-regulate the expression of cytoplasmic and mitochondrial proteins, metabolic enzymes, and ligases, playing pivotal roles in metabolism and genetic information processing. These proteins, featuring membrane linkers and phosphatases, potentially impact peptide and amino acid biosynthesis, thereby affecting meat quality modifications.

High-Pressure Treatment in Combination with Reduced Sodium for Improving the Physicochemical Properties and Sensory Qualities of Pork Gels

High-pressure treatment was utilized in this study to produce high-quality, reduced-sodium pork gels with desirable texture and sensory properties, addressing the challenge of maintaining quality in low-sodium meat products to meet health-conscious consumer demands. High-pressure treatment applied within the range of 150-200 MPa significantly reduced cooking loss while maintaining moisture content and provided an ideal network structure for reduced-sodium pork gels. High-pressure treatment at up to 100-200 MPa, in combination with added sodium chloride and sodium polyphosphate, was evaluated for its effects on gel texture, with results indicating that high-pressure treatment significantly improved breaking stress (increased by 10.01% under 150 MPa and 14.66% under 200 MPa), modulus of elasticity (increased by 14.77% under 150 MPa and 24.17% under 200 MPa), and hardness (increased by 11.12% under 150 MPa and 11.45% under 200 MPa). Rheological characteristic measurements revealed that gel strength was highest at 150 MPa (G' = 443,000 Pa; G″ = 66,300 Pa and tanδ = 0.15), which showed higher G' and G″ values and similar tanδ compared to the 0.1 MPa, 2% NaCl + 0.5% SPP condition (G' = 334,000 Pa; G″ = 49,200 Pa; tanδ = 0.148). Protein analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a reduction in the α-actinin band with increased pressure, which suggested protein interactions were enhanced. Differential scanning calorimetry analysis indicated that protein denaturation occurred more readily at higher pressures (0.071 J/g at 0.1 MPa, 0.057 J/g at 150 MPa, and 0.039 J/g at 200 MPa). These findings underscore the value of treatment under high pressure at 150 MPa developing reduced-sodium meat products with desirable texture and flavor characteristics.

Effect of denaturation rate of sliver carp myosin induced by alcohols on its thermal aggregation behavior and gel properties

The effects of ethanol, 1,2-propanediol, and glycerol at concentrations from 10 % to 40 % on the thermal denaturation and aggregation of silver carp (Hypophthalmichthys molitrix) myosin were investigated. The results revealed that ethanol and 1,2-propanediol induced thermal denaturation of myosin more rapidly than glycerol, which minimally impacted the secondary structure. At 10 % concentration, 1,2-propanediol significantly influenced myosin's secondary structure more than ethanol. While at a concentration of 20 %, ethanol prompted faster thermal denaturation and aggregation, resulting in higher turbidity than 1,2-propanediol (P < 0.05). Notably, higher concentrations of ethanol (30 % and 40 %) and 1,2-propanediol (40 %) induced the formation of non-disulfide covalent bonds, contributing to excessive myosin aggregation. Furthermore, hydrophobic interactions emerged as crucial within myosin aggregation in glycerol solutions during heating. Additionally, the effects of three alcohols at 1 %, 3 %, and 5 % on the gel properties were investigated. The results showed that an appropriate concentration of 1,2-propanediol (3 %) and glycerol (5 %) significantly enhanced the gel properties by inducing desirable unfolding and aggregation of myosin molecules. These findings offer a theoretical foundation for utilizing alcohol additives to enhance the gel quality of heat-induced surimi.

Systematic free energy insights into the enhanced dispersibility of myofibrillar protein in low-salt solutions through ultrasound-assisted enzymatic deamidation

This work aimed to investigate the effects of ultrasound assisted enzymatic deamidation by protein-glutaminase (PG) on the dispersion of myofibrillar protein (MP) in low-salt solutions. The solubility, structural characteristics, transmission electron microscopy, asymmetric-flow field-flow fractionation, steady shear rheological property and multiple light scattering of MP deamidated by PG (MP-PG) and MP pretreated with ultrasound followed by PG deamidation (MP-U-PG) were determined. Molecular docking and molecular dynamics (MD) simulations were used to estimate the interaction between PG and MP. Under ultrasound assistance, the MP deamidated for 16 h (MP-U-PG16) showed the highest solubility (80.1 %) in low-salt conditions, which is attributed to its highest absolute zeta potential and smallest particle size. Although secondary structure analysis showed that MP-PG and MP-U-PG had an increased α-helix ratio and a decreased β-sheet ratio, ultrasonic treatment had a significantly influence on the MD results. The results manifested that hydrogen bond was the primary forces driving the binding between PG and MP, and the hydrogen bond and hydrophobic interaction were the dominant forces responsible the binding between PG and MP pretreated with ultrasound. According to the energy landscapes theory, ultrasound could overcome the energy barriers through external force input and find the best pathway to achieve the final lowest energy state. Our research contributed to the improvement of the colloidal dispersibility of MPs under low-salt conditions and the regulation of protein interaction by ultrasound assistance.

Optimization of pulsed electric fields-assisted thawing process conditions and its effect on the quality of Zhijiang duck meat

Freezing storage is a common preservation method for industrialized duck meat. However, both the frozen storage and thawing processes of meat can affect meat quality. Therefore, appropriate thawing methods are crucial for maintaining good meat quality. In this study, a pulsed electric field (PEF) was used for thawing zhijiang duck meat and the freshed duck meats were used as control. Optimization of the PEF-assisted thawing process and its effect on the quality of zhijiang duck meat were analyzed. Our data showed that the shear force in the 2 kV/cm PEF-assisted thawing group was the lowest in PEF-assisted thawing groups. The color of zhijiang duck meat in the 2 kV/cm PEF-assisted thawing group was optimal. The 2 kV/cm PEF-assisted thawing could improve the texture characteristics of zhijiang duck meat and enhance water holding capacity of zhijiang duck meat. PEF-assisted thawing could better maintain the microstructure of zhijiang duck meat. Our data showed that if the intensity or duration of PEF treatment is too high, the quality of duck meat will actually decrease. Therefore, appropriate parameters should be selected in practical applications, which will provide a reference for the application of PEF-assisted thawing on the market.

Enhacing emulsification of meat broth system mixed with myofibrillar proteins and type I collagen: The role of NaCl and heat

A mixed system with a 5:1 ratio of beef myofibrillar protein to type I collagen was prepared to mimic meat broths. The study aimed to determine the combined effects of various NaCl concentrations (0, 0.2 M, 0.4 M, 0.6 M) and heat treatment on solubility, emulsifying properties (EAI, ESI), viscosity, and particle size of the mixed protein system. Mechanistic changes were examined through molecular interactions, intrinsic fluorescence, protein molecular weight, and Raman spectroscopy. The results showed that, without heat treatment, NaCl enhanced solubility, EAI, ESI, emulsion viscosity, and hydrogen bonding. After heating (90 °C, 30 min), elevated 0.4-0.6 M NaCl created an unstable, crowded environment, resulting in protein aggregation and reduced solubility and emulsifying performance. The results indicated that heating at 90 °C with 0.2 M NaCl was beneficial for meat emulsification, providing valuable production guidance for optimizing the formulation of meat products with low salt and high emulsifying properties.

Antioxidant Activity and DPP-IV Inhibitory Effect of Fish Protein Hydrolysates Obtained from High-Pressure Pretreated Mixture of Rainbow Trout (Oncorhynchus mykiss) and Atlantic Salmon (Salmo salar) Rest Raw Material

The use of fish rest raw material for the production of fish protein hydrolysates (FPH) through enzymatic hydrolysis has received significant interest in recent decades. Peptides derived from fish proteins are known for their enhanced bioactivity which is mainly influenced by their molecular weight. Studies have shown that novel technologies, such as high-pressure processing (HPP), can effectively modify protein structures leading to increased biological activity. This study investigated the effect of various HPP conditions on the molecular weight distribution, antioxidant activity, and dipeptidyl-peptidase IV (DPP-IV) inhibitory effect of FPH derived from a mixture of rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar) rest raw material. Six different treatments were applied to the samples before enzymatic hydrolysis; 200 MPa × 4 min, 200 MPa × 8 min, 400 MPa × 4 min, 400 MPa × 8 min, 600 MPa × 4 min, and 600 MPa × 8 min. The antioxidant and DPP-IV inhibitory effects of the extracted FPH were measured both in vitro and at cellular level utilizing human intestinal Caco-2 cells. The results indicated that low and moderate pressures (200 and 400 MPa) increased the proportion of larger peptides (2-5 kDa) in the obtained FPH, while treatment at 600 MPa × 4 min resulted in a higher proportion of smaller peptides (1-2 kDa). Furthermore, HPP led to the formation of peptides that demonstrated increased antioxidant activity in Caco-2 cells compared to the control, whereas their potential antidiabetic activity remained unaffected.

Non-covalent interaction between lactoferrin and theaflavin: Focused on the structural changes, binding mechanism, and functional properties

In this study, non-covalent binding mechanism of lactoferrin (LaF)-theaflavin (TF) complex and its functional properties were investigated. Multi-spectroscopic analyses showed that the secondary structure of LaF was altered with increasing TF concentration. The non-covalent binding of TF to LaF resulted in a reduction in the content of the α-helix and β-sheet, as well as a decrease in the fluorescence intensity of LaF. DSC result showed that non-covalent binding of TF improved thermal stability of LaF. Molecular dynamics simulations confirmed that the stable binding of LaF-TF was driven by hydrogen bonding and hydrophobic interactions. Additionally, non-covalent binding of TF increased the antioxidant capacity and emulsifying properties of LaF. Dynamic interfacial tension indicated that the strong interaction between LaF and TF reduced the interfacial tension, but improved the rheological properties of LaF. The functional characteristics of the non-covalent complex was effectively enhanced, paving the way for its potential use in the food industry.

High hydrostatic pressure reduces inflammation induced by litchi thaumatin-like protein via altering active domain

Thaumatin-like proteins (TLP), existing in various fruits, have allergenic and pro-inflammatory activities. The current research attempts to reduce the pro-inflammatory activity of litchi TLP (LcTLP) through high hydrostatic pressure (HHP). This study demonstrated that HHP (250-500 MPa, 5-10 min) was a potential technique to reduce the pro-inflammatory activity of LcTLP, which was attributed to the irreversible destruction of the active domain, ie., V-cleft. SDS-PAGE showed no change in the protein profile. Continuous HHP treatment promoted LcTLP unfolding and then reassembling (400 MPa was the transition pressure), and the content of β-sheets decreased from 35.4% to 31.1%. HHP treatment could mitigate inflammatory responses of LcTLP, as confirmed by ELISA and western blot. Molecular dynamics simulations showed significant changes in the residue network under HHP, thereby affecting the V-cleft. These findings provide a theoretical explanation and structural insights into the HHP-induced reduction of pro-inflammatory activity of LcTLP.

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.

Insights into the in vitro digestibility and rheology properties of myofibrillar protein with different incorporation types of curdlan

This study investigated the effects of two forms of curdlan, namely curdlan thermoreversibility (CT) and curdlan powder (CP), on in vitro digestion and viscoelastic properties of myofibrillar protein (MP). As the level of curdlan (0.1-0.5%) increased, pepsin digestibility and pancreatin digestibility significantly decreased, active sulfhydryl group also decreased, while surface hydrophobicity and total sulfhydryl groups increased. Meanwhile, curdlan enhanced the secondary and tertiary structures of MP. As the pepsin digest, α-helix gradually transformed into random coil. Furthermore, the viscosity, storage modulus (G") and loss modulus (G') increased with the CT or CP addition. After in vitro digestion, the viscoelasticity significantly decreased with a dose-response. Molecular dynamics simulations showed hydrogen bond formation (2.86 on average) between MP and curdlan contributing to reduced radius of gyration and solvent accessible surface area. Overall, this study highlighted curdlan as a promising ingredient to modulate structural properties and digestibility of MP, especially in pre-hydrated (CT) groups.

Effect of psyllium husk powder on the gelation behavior, microstructure, and intermolecular interactions in myofibrillar protein gels from Andrias davidianus

The interaction between proteins and soluble dietary fibers plays a vital role in the development of animal-derived foods. Herein, the effects of different contents (0-3.0%) of round-bracted psyllium husk powder (PHP) on the gelation behavior, microstructure, and intermolecular interactions of Andrias davidianus myofibrillar protein (MP) were investigated. Rheological and chemical forces suggested that PHP (1.5%-2.0%) enhanced the functional properties of MP at low ionic strength, thereby increasing the viscoelasticity of mixed gels. SDS-PAGE revealed that PHP reinforced the cross-linking and aggregation of protein molecules. Circular dichroism spectroscopy, low-field nuclear magnetic resonance, and scanning electron microscopy demonstrated that PHP induced the transformation of α-helix (decreased by 14.85%) to an ordered β-sheet structure (increased by 81.58%), which was more favorable for the formation of dense network structure and improved (10.53%) the water retention of MP gels. This study provided new insights for PHP to effectively meliorate the heat-induced gelling properties of MP.

Improvement on gel properties of chicken myofibrillar protein with electron beam irradiation: Based on protein structure, gel quality, water state

This study aimed to investigate the effects of electron beam (E-beam) irradiation at different doses (0-15 kGy) on the solubility, rheological properties, emulsification characteristics, and moisture distribution of chicken myofibrillar proteins (MPs). Irradiation treatment notably increased the solubility, surface hydrophobicity, emulsification properties, and apparent viscosity of MPs, based on conformational changes caused by irradiation-induced oxidative denaturation of proteins. However, high doses of irradiation (15 kGy) induced in excessive cross-linking and aggregation of proteins, reducing the solubility, emulsification properties, and shear stress. Degradation of myosin heavy and light chains in irradiated MPs increased the content of β-turns and random coils. Additionally, the initial relaxation times of T21 and T22 in irradiated protein gels were reduced, and the peak value of P21 was increased, which improved the water-capturing ability of protein gels. Altogether, these results findings suggest that electron beam irradiation can be applied as a potential technique for modifying muscle proteins.

Elucidating the formation of the uniform "glass-like" texture in dried-bonito during processing based on microstructure and protein properties

Dried-bonito (Katsuobushi) exhibits a unique uniform "glass-like" texture after traditional smoke-drying. Herein, we developed a novel processing method for dried-bonito and elucidated the mechanism of transformation of loose muscle into a "glass-like" texture in terms of texture, microstructure, and protein properties. Our findings showed that the unfolding and aggregation of proteins after thermal induction was a key factor in shaping the "glass-like" texture in bonito muscle. During processing, myofibrils aggregated, the originally alternating thick and thin filaments contracted laterally and aligned into a straight line, and protein cross-linking increased. Secondary structural analysis revealed a reduction in unstable β-turn content from 26.28% to 15.06%. Additionally, an increase in the content of SS bonds was observed, and the conformation changed from g-g-t to a stable g-g-g conformation, enhanced protein conformational stability. Taken together, our findings provide a theoretical basis for understanding the mechanism of formation of the uniform "glass-like" texture in dried-bonito.

Fucoidan-Vegetable Oil Emulsion Applied to Myosin of Silver Carp: Effect on Protein Conformation and Heat-Induced Gel Properties

How to improve the gel properties of protein has become a research focus in the field of seafood processing. In this paper, a fucoidan (FU)-vegetable oil emulsion was prepared, and the mechanism behind the effect of emulsion on protein conformation and the heat-induced gel properties was studied. The results revealed that the FU-vegetable oil complex caused the aggregation and cross-linking of myosin, as well as increased the surface hydrophobicity and total sulfhydryl content of myosin. In addition, the addition of the compound (0.3% FU and 1% vegetable oil) significantly improved the gel strength, hardness, chewiness, and water-holding capacity of the myosin gel (p < 0.05). In particular, when the addition of camellia oil was 1%, the gel strength, hardness, chewiness, and water-holding capacity had the highest values of 612.47 g.mm, 406.80 g, 252.75 g, and 53.56%, respectively. Simultaneously, the emulsion (0.3% FU-1% vegetable oil) enhanced the hydrogen bonds and hydrophobic interaction of the myosin gels. The image of the microstructure showed that the emulsion with 0.3% FU-1% vegetable oil improved the formation of the stable three-dimensional network structure. In summary, the FU-vegetable oil complex can promote unfolding of the protein structure and improve the gel properties of myosin, thus providing a theoretical basis for the development of functional surimi products.

Unraveling the mechanism of aroma loss during prolonged hot air drying of non-smoked bacon: Insights into aroma compounds generation and retention

In this study, the potential mechanism of aroma loss in non-smoked bacon due to excessive hot air drying (beyond 24 h) was investigated, focusing on protein conformational changes and the inhibition of heme protein-mediated lipid oxidation by oleic acid. The results showed that prolonged hot-air drying caused a stretching of the myofibrillar protein (MP) conformation in bacon before 36 h, leading to an increase in reactive sulfhydryl groups, surface hydrophobicity, and the exposure of additional hydrophobic sites. Consequently, the binding ability of MP to the eight key aroma compounds (hexanal, 1-octen-3-ol, (E)-2-nonenal, 3-methyl-butanoic acid, 2-undecenal, (E, E)-2,4-decadienal, 2,3-octanedione, and dihydro-5-pentyl-2(3H)-furanone) was enhanced, resulting in their retention. On the other hand, a sustained increase in oleic acid levels has been demonstrated to effectively inhibit heme protein-mediated lipid oxidation and the formation of these key aroma compounds. Using lipidomic techniques, 30 lipid molecules were identified as potential precursors of oleic acid during the bacon drying process. Among these precursors, triglycerides (16:0/18:0/18:1) may be the most significant.

Preparation, characterization, and mechanism of DPP-IV inhibitory peptides derived from Bactrian camel milk

In this study, double enzyme hydrolysis significantly enhanced the DPP-IV inhibition rate compared to single enzyme. The α + K enzymes exhibited the highest inhibition rate. Ultrasonic pretreatment for 30 min improved the hydrolysis efficiency and DPP-IV inhibition rate, potentially due to the structural changes in hydrolysates, such as the increased surface hydrophobicity, and reduced particle size, α-helix and β-turn. Six peptides were screened and verified in vitro. QPY, WPEYL, and YPPQVM displayed competitive inhibition, while LPAAP and IPAPSFPRL displayed mixed competitive/non-competitive inhibition. The interactions between these six peptides and DPP-IV primarily occurred through hydrogen bonds, electrostatic and hydrophobic interactions. Network pharmacological analysis indicated that LPAAP might inhibit DPP-IV activity trough interactions with diabetes-related targets such as CASP3, HSP90AA1, MMP9, and MMP9. These results uncover the potential mechanism of regulating blood glucose by camel milk hydrolysates, establishing camel milk peptide as a source of DPP-IV inhibitory peptide.

Development of a magnetic separation method for rapid isolation and enrichment of bacteria in raw pork using chitosan functionalized magnetic Fe3O4@MIL-100(Fe) composites

In this study, a pretreatment method based on a magnetic capture probe for the rapid isolation and enrichment of bacteria from raw pork was developed. The chitosan immobilized Fe3O4@MIL-100(Fe) was prepared as a capture probe for total bacterial counts through the electrostatic interaction of positively charged chitosan and the negatively charged substances on the surface of bacteria. The interference of matrix in pork samples on this method was studied and removed by differential centrifugation. The results showed the capture probe had a great selectivity binding and magnetic separation properties for the tested six common bacteria in pork. Under the optimal conditions, the capture efficiency of the bacteria (105 CFU mL-1) from pork surface samples was all above 90%. The capture efficiency of the bacteria in a homogenate system was greatly decreased due to the interference of sarcoplasmic protein and myofibrillar protein in pork. The matrix effect was mitigated by a differential centrifugation method, and the capture efficiency of all six bacteria was >80%. The developed magnetic separation method took 40 min and showed good isolation and enrichment properties of bacteria. Thus, the proposed method is expected to provide a simple, convenient, and time-saving pretreatment method for the detection of total bacterial counts in pork.

Performance and protein conformation of thermally treated silver carp (Hypophthalmichthys molitrix) and scallop (Argopecten irradians) blended gels

BACKGROUND

The quality of surimi-based products can be improved by combining the flesh of different aquatic organisms. The present study investigated the effects of incorporating diverse ratios of unwashed silver carp (H) and scallop (A) and using various thermal treatments on the moisture, texture, microstructure, and conformation of the blended gels and myofibrillar protein of surimi.

RESULTS

A mixture ratio of A:H = 1:3 yielded the highest gel strength, which was 60.4% higher than that of scallop gel. The cooking losses of high-pressure heating and water-bath microwaving were significantly higher than those of other methods (P < 0.05). Moreover, the two-step water bath and water-bath microwaving samples exhibited a more regular spatial network structure compared to other samples. The mixed samples exhibited a microstructure with a uniform and ordered spatial network, allowing more free water to be trapped by the internal structure, resulting in more favorable gel properties. The thermal treatments comprehensively modified the tertiary and quaternary structures of proteins in unwashed mixed gel promoted protein unfurling, provided more hydrophobic interactions, enhanced protein aggregation and improved the gel performance.

CONCLUSION

The findings of the present study improve our understanding of the interactions between proteins from different sources. We propose a new method for modifying surimi's gel properties, facilitating the development of mixed surimi products, as well as enhancing the efficient utilization of aquatic resources. © 2024 Society of Chemical Industry.

Effects of ultrasound-assisted dry-curing on water holding capacity and tenderness of reduced‑sodium pork by modifying salt-soluble proteins

This study investigated the effects of ultrasound-assisted dry-curing (UADC) on water holding capacity (WHC) and tenderness of pork at different powers and times, and the mechanism was discussed by considering the functional and structural properties of salt-soluble proteins (SSP). The results showed the application of appropriate UADC treatments (300 W, 60 min) have disruptively affected the muscle structure and decreased the size of the SSP particles (P < 0.05), resulting in the increased concentration of active sulfhydryl and surface hydrophobicity (P < 0.05). These modifications facilitated the dissociation of the myofibrillar structure and the dissolution of more connected proteins, which in turn improved the WHC and tenderness of the pork (P < 0.05). Nevertheless, extended periods of high-power UADC treatments negatively affected the WHC and tenderness of dry-cured pork (P < 0.05). In general, using SSP modified by UADC provides a novel strategy for enhancing the WHC and tenderness of dry-cured products.

Preparation, Characterization and Formation Mechanism of High Pressure-Induced Whey Protein Isolate/κ-Carrageenan Composite Emulsion Gel Loaded with Curcumin

In order to explore the formation mechanism of the emulsion gel induced by high pressure processing (HPP) and its encapsulation and protection of functional ingredients, a curcumin-loaded whey protein isolate (WPI)/κ-carrageenan (κ-CG) composite emulsion gel induced by HPP was prepared. The effect of pressure (400, 500 and 600 MPa), holding time (10, 20 and 30 min) and concentration of κ-CG (0.8%, 1.0% and 1.2%, w/v) on the swelling rate, gel strength, the stability of curcumin in the emulsion gel, water distribution and its mobility, as well as the contents of interface protein were characterized. The results showed that the addition of κ-CG significantly reduced the protein concentration required for the formation of emulsion gel induced by HPP and greatly reduced the swelling rate of the emulsion gel. The gel strength and storage stability of the composite emulsion gels increased with the increase in pressure (400-600 MPa) and holding time (10-30 min). When the pressure increased to 500 MPa, the stability of curcumin in the emulsion gel significantly improved. When the ratio of WPI to κ-CG was 12:1 (the κ-CG concentration was 1.0%), both the photochemical and thermal stability of curcumin were higher than those of the other two ratios. The HPP significantly increased the mobility of monolayer water in the system, while the mobility of multilayer water and immobilized water was significantly reduced. Increasing the holding time and the concentration of κ-CG both can result in an increase in the interfacial protein content in the oil/water system, and the HPP treatment had a significant effect on the composition of the interfacial protein of the emulsion gel.

Effects of high voltage pulsed electric field on structural properties and immune reactivity of arginine kinase in Fenneropenaeus chinensis

To evaluate the effect of high voltage pulsed electric field (PEF) treatment (10-20 kV/cm, 5-15 min) on the structural characteristics and sensitization of crude extracts of arginine kinase from Fenneropenaeus chinensis. By simulated in vitro gastric juice digestion (SGF), intestinal juice digestion (SIF) and enzyme-linked immunosorbent assay (ELISA), AK sensitization was reduced by 42.5% when treated for 10 min at an electric field intensity of 15 kV/cm. After PEF treatment, the α-helix content decreased, and the α-helix content gradually changed to β-sheet and β-turn. Compared to the untreated group, the surface hydrophobicity increased and the sulfhydryl content decreased. SEM and AFM analyses showed that the treated sample surface formed a dense porous structure and increased roughness. The protein content, dielectric properties, and amino acid content of sample also changed significantly with the changes in the treatment conditions. Non-thermal PEF has potential applications in the development of hypoallergenic foods.

High-pressure microfluidisation positively impacts structural properties and improves functional characteristics of almond proteins obtained from almond meal

Almond protein isolate (API) obtained from almond meal was processed using dynamic high-pressure microfluidisation (0, 40, 80, 120, and 160 MPa pressure; single pass). Microfluidisation caused significant reductions in the particle size and increased absolute zeta potential. SDS-PAGE analysis indicated reduction in band intensity and the complete disappearance of bands beyond 80 MPa. Structural analysis (by circular dichroism, UV-Vis, and intrinsic-fluorescence spectra) of the API revealed disaggregation (up to 80 MPa) and then re-aggregation beyond 80 MPa. Significant increments in protein digestibility (1.16-fold) and the protein digestibility corrected amino acid score (PDCAAS; 1.15-fold) were observed for the API (80 MPa) than control. Furthermore, significant improvements (P < 0.05) in the functional properties were observed, viz., the antioxidant activity, protein solubility, and emulsifying properties. Overall, the results revealed that moderate microfluidisation treatment (80 MPa) is an effective and sustainable technique for enhancing physico-chemical and functional attributes of API, thus potentially enabling its functional food/nutraceuticals application.

Enhancing Functional Properties and Protein Structure of Almond Protein Isolate Using High-Power Ultrasound Treatment

The suitability of a given protein for use in food products depends heavily on characteristics such as foaming capacity, emulsifiability, and solubility, all of which are affected by the protein structure. Notably, protein structure, and thus characteristics related to food applications, can be altered by treatment with high-power ultrasound (HUS). Almonds are a promising source of high-quality vegetable protein for food products, but their physicochemical and functional properties remain largely unexplored, limiting their current applications in foods. Here, we tested the use of HUS on almond protein isolate (API) to determine the effects of this treatment on API functional properties. Aqueous almond protein suspensions were sonicated at varying power levels (200, 400, or 600 W) for two durations (15 or 30 min). The molecular structure, protein microstructure, solubility, and emulsifying and foaming properties of the resulting samples were then measured. The results showed that HUS treatment did not break API covalent bonds, but there were notable changes in the secondary protein structure composition, with the treated proteins showing a decrease in α-helices and β-turns, and an increase in random coil structures as the result of protein unfolding. HUS treatment also increased the number of surface free sulfhydryl groups and decreased the intrinsic fluorescence intensity, indicating that the treatment also led to alterations in the tertiary protein structures. The particle size in aqueous suspensions was decreased in treated samples, indicating that HUS caused the dissociation of API aggregates. Finally, treated samples showed increased water solubility, emulsifying activity, emulsifying stability, foaming capacity, and foaming stability. This study demonstrated that HUS altered key physicochemical characteristics of API, improving critical functional properties including solubility and foaming and emulsifying capacities. This study also validated HUS as a safe and environmentally responsible tool for enhancing desirable functional characteristics of almond proteins, promoting their use in the food industry as a high-quality plant-based protein.

Fabrication and characterization of curcumin-loaded composite nanoparticles based on high-hydrostatic-pressure-treated zein and pectin: Interaction mechanism, stability, and bioaccessibility

We successfully designed curcumin (Cur)-loaded composite nanoparticles consisting of high-hydrostatic-pressure-treated (HHP-treated) zein and pectin with a pressure of 150 MPa (zein-150 MPa-P-Cur), showing nano-spherical structure with high zeta-potential (-36.72 ± 1.14 mV) and encapsulation efficiency (95.64 ± 1.23 %). We investigated the interaction mechanism of the components in zein-150 MPa-P-Cur using fluorescence spectroscopy, molecular dynamics simulation, Fourier-transform infrared spectrometry and scanning electron microscopy techniques. Compared with zein-P-Cur, the binding sites and binding energy (-53.68 kcal/mol vs. - 44.22 kcal/mol) of HHP-treated zein and Cur were increased. Meanwhile, the interaction force among HHP-treated zein, pectin, and Cur was significantly enhanced, which formed a tighter and more stable particle structure to further improve package performance. Additionally, Cur showed the best chemical stability in zein-150 MPa-P-Cur. And the bioavailability of Cur was increased to 65.53 ± 1.70 %. Collectively, composite nanoparticles based on HHP-treated zein and pectin could be used as a promising Cur delivery system.

Properties of Myofibrillar Protein in Frozen Pork Improved through pH-Shifting Treatments: The Impact of Magnetic Field

The present study demonstrates the effects of pH-shifting treatments and magnetic field-assisted pH-shifting treatments on the properties of myofibrillar protein (MP) in frozen meat. The solubility results indicate that the pH-shifting treatments increased the solubility of MP from 16.8% to a maximum of 21.0% (pH 9). The values of surface hydrophobicity and protein particle size distribution indicate that the pH-shifting treatment effectively inhibited protein aggregation through electrostatic interactions. However, under higher pH conditions (pH 10, 11), the treatments assisted by the magnetic field increased the degree of aggregation. The total thiol content and SDS-PAGE results further suggest that the magnetic field-assisted pH-shifting treatment accelerated the formation of covalent bonds among MPs under the alkaline environment. The results of the Differential Scanning Calorimetry (DSC) and protein secondary structure analysis indicate that the magnetic field promoted the unfolding of protein structures in an alkaline environment, markedly reducing the effective pH levels of pH-shifting. Electron paramagnetic resonance (EPR) data indicate that the phenomenon might be associated with the increased concentration of free radicals caused by the magnetic field treatment. In summary, the application of magnetic field-assisted pH-shifting treatments could emerge as a potent and promising strategy to improve the protein properties in frozen meat.

Remodeling mechanism of gel network structure of soy protein isolate amyloid fibrils mediated by cellulose nanocrystals

The differences in the gelling properties of soy protein isolate (SPI) and soy protein isolate amyloid fibrils (SAFs) as well as the role of cellulose nanocrystals (CNC) in regulating their gel behaviors were investigated in this study. The binding of CNC to β-conglycinin (7S), glycinin (11S), and SAFs was predominantly driven by non-covalent interactions. CNC addition reduced the particle size, turbidity, subunit segments, and crystallinity of SPI and SAFs, promoted the conversion of α-helix to β-sheet, improved the thermal stability, exposed more tyrosine and tryptophan residues, and enhanced the intermolecular interactions. A more regular and ordered lamellar network structure was formed in the SAFs-CNC composite gel, which could be conducive to the improvement of gel quality. This study would provide theoretical reference for the understanding of the regulatory mechanism of protein amyloid fibrils gelation as well as the high-value utilization of SAFs-CNC complex as a functional protein-based material or food ingredient in food field.

Ultra-high pressure improved gelation and digestive properties of Tai Lake whitebait myofibrillar protein

This study investigated the effects of ultra-high pressure (UHP) at different levels on the physicochemical properties, gelling properties, and in vitro digestion characteristics of myofibrillar protein (MP) in Tai Lake whitebait. The α-helix gradually unfolded and transformed into β-sheet as the pressure increased from 0 to 400 MPa. In addition, the elastic modulus (G') and viscous modulus (G'') of the 400 MPa-treated MP samples increased by 4.8 and 3.8 times, respectively, compared with the control group. The gel properties of the MP also increased significantly after UHP treatment, e.g., the gel strength increased by a 4.8-fold when the pressure reached 400 Mpa, compared with the control group. The results of in vitro simulated digestion showed that the 400 MPa-treated MP gel samples showed a 1.8-fold increase in digestibility and a 69.6 % decrease in digestible particle size compared with the control group.

Study on the thawing characteristics of beef in ultrasound combined with plasma-activated water

The effects of deionized water thawing (DT), plasma-activated water thawing (PT), ultrasound (150 W, 40 kHz) combined with deionized water thawing (UDT), and ultrasound combined with plasma-activated water thawing (UPT) on the thawing characteristics and the physicochemical properties of the beef were investigated. The results showed that the UPT group had a faster thawing rate (38 % higher compared to the PT group) and good bactericidal ability (75 % higher compared to the UDT group), and had no adverse effect on the color and pH value of the beef. Plasma-activated water (PAW) can maintain the stability of the beef fiber, improve the water holding capacity (WHC), inhibit lipid oxidation, and reduce the loss of soluble substances such as protein. Therefore, UPT thawing is a promising meat thawing technology, which provides practical guidance and methods for the wide application of UPT in the field of meat thawing.