Myofibrillar Protein Gel Research Articles

A comparative study of different soybean oil forms on the physicochemical properties of surimi myofibrillar protein gel: The role of soybean protein isolate and κ-carrageenan

Natural soybean oil, Pickering emulsion, high-internal-phase emulsion (HIPE), and emulsion gel were prepared to investigate their effects on the physicochemical properties of surimi myofibrillar protein gels. Their effects on gel strength ranked as: emulsion gel > Pickering emulsion > HIPE > soybean oil. At the same oil content, the emulsion gel exhibited higher G' than the other forms whereas natural oil exhibited the lowest G', and T22 was smaller in the emulsion gel group, indicating that the emulsion gel enhanced the interaction between water molecules and protein macromolecules. FT-IR testified that 9 % natural oil reduced the β-sheet content to 26.34 %, whereas Pickering emulsion, HIPE, and emulsion gel recovered the β-sheet content to 31.30 %, 36.17 %, and 32.69 %, respectively. Emulsion gel led to fewer voids, and the oil droplets in emulsion gel were more regularly spherical and homogeneously dispersed in the gel matrix, which might be attributed to the filling effects as well as “bridging action” of soybean protein isolate and κ-carrageenan within surimi proteins. In conclusion, we demonstrated emulsion gel as a good replacer to mitigate the negative effect of oil on the texture and structure of surimi gels, which would be a promising approach for oil supplementation in surimi production.

Effects of moderately oxidized lard on myofibrillar protein emulsion gels: Gel-forming properties, water distribution, and digestibility

Emulsion gels were prepared by adding lard with different degrees of oxidation (0, 1, 2, 3, 4, and 5 h, 110 °C) to porcine myofibrillar proteins (MP). The findings demonstrated that changes in sulfhydryl content and carbonyl content reflected that oxidized lard induced the oxidation of MP. Compared with the control (CON), moderately oxidized lard (2 h) led to the unfolding of the protein structure, increased β-sheet content, and exposed hydrophobic groups. These modifications facilitated interactions between the protein and lard at the interface, enhancing the emulsifying properties of MPs. Furthermore, the moderate oxidation of lard (2 h) enhanced the organization of the gel structure and improved the gel performance of MPs, resulting in uniform water distribution. In contrast, the hardness and springiness of MP gel treated with excessively oxidized lard (5 h) were significantly reduced (p < 0.05). The microstructure of MP gel also exhibited irregular aggregation, resulting in a decline in protein digestibility. In addition, lard oxidation (2 h) had a positive effect on maintaining gel stability during storage.

Effect of NaCl replacement by other salt mixtures on myofibrillar proteins: Underlining protein structure, gel formation, and chewing properties.

The protein structure, gel changes, and chewing properties of low-sodium myofibrillar protein (MP) prepared by compound chloride salts (KCl/MgCl2, KCl/CaCl2, and KCl/MgCl2/CaCl2) and different substitution degrees (10%, 25%, and 40%) at same ionic strength (0.6M) were investigated. The results revealed that the low-sodium MP gels containing CaCl2 manifested more liquid loss and less moisture content accompanied by obvious morphological shrinkage, while KCl/MgCl2 contributed to the gel juiciness. At high substitution degree of 40%, KCl/CaCl2 substitution rendered the gel with dense structure and highest strength, but worse water retention capacity. Using other compound chloride salts influenced the chewing efficiency, and CaCl2 substitution made the gel relatively hard to chew. The inhomogeneous structure accompanied by cluster blocks in KCl/CaCl2-substituted MP gel accelerated the overall fracture rate. During heating process, more proteins in CaCl2-substituted MP did not participate in gel formation, intervening the final gel properties. The chloride salt mixtures containing MgCl2, rather than CaCl2, avoided or alleviated the liquid loss and shrinkage of low-sodium MP gel within the substitution degree of 10%-40%, and substitution degree not exceeding 25% was more reasonable for the controlled qualities.

Rheological properties and in vitro digestibility of chicken breast myofibrillar protein containing various psyllium (Plantago ovata) husk concentrations

SummaryMost dietary fibres improved rheological properties but negatively impacted digestibility. However, the effect of psyllium husk powder (PHP) on digestibility has not been yet reported. Thus, this study aimed to evaluate the rheological properties and digestibility of chicken myofibrillar protein (MP) containing different concentrations of PHP (0%, 0.5%, 1.0%, 1.5%) at 0.45 m NaCl. To assess the rheological properties of MP, viscosity, hydrophobicity, disulphide bond, SDS–PAGE, cooking yield and gel strength were evaluated. The addition of PHP enhanced water retention capacity and protein–protein interactions in the MP system. To evaluate the effect of PHP on digestibility, protein digestibility, SDS–PAGE and microstructure observations were performed. It was confirmed that the addition of PHP improved the protein digestibility of MP by measuring the differences in protein content (%). Therefore, the addition of PHP into MP gel improved not only the rheological properties but also the protein digestibility during in vitro digestion.

Effect of ultrasound combined with highland barley dietary fiber on gel properties of reduced-salt chicken breast myofibrillar protein.

This study aimed to investigate the effect of ultrasound combined with highland barley dietary fiber (HBDF) on the quality of reduced-salt chicken breast myofibrillar protein (MP) gel. The molecular forces maintaining gel structure, the gelling formation process, and gel microstructure of different groups, two control groups (2% sodium chloride [NaCl] group, 1% NaCl group), and four treatment groups (0.3% HBDF+U5, 0.3% HBDF+U10, 0.5% HBDF+U5, and 0.5% HBDF+U10) were examined. Results indicated significant improvements (p<0.05) in gel properties such as water-holding capacity, textural characteristics, and color of the MP gel of the four treatment groups compared to Control 2 (1% NaCl) group. Furthermore, the second structural alterations were characterized by increase β-sheet, β-turn, and random coil structure contents in treatment groups, especially in 0.3% HBDF+U5 and 0.5% HBDF+U5 groups; in addition, the exposure of more hydrophobic groups and the formation of disulfide bonds and hydrogen bonds were promoted in treatment groups, thus enhancing protein aggregation and gel quality. Finally, compared to Control 2 (1% NaCl) group, more compact and uniform gel network structures and pores inside the composite gels were observed in treatment groups. In conclusion, the findings demonstrated that the application of ultrasound in combination with HBDF improved the gelling characteristics of reduced-salt chicken breast MP gel, especially 0.3% HBDF+U5 and 0.5% HBDF+U5 groups.

Effect of chitosan oligosaccharides with different molecular weight in alleviating textural deterioration of chicken myofibrillar protein gel with high-temperature treatment

The molecular weight (MW) of oligosaccharides on gel properties of myofibrillar protein (MP) at high temperature remains unclear. In this study, it was found that chitosan oligosaccharides (CO) with different MW all significantly alleviated the textural deterioration of MP gel with high-temperature treatment. Moreover, MP-CO gel with the largest MW had the highest breaking force and the lowest cooking loss. Low-field NMR results further indicated that MP-CO gel with larger MW of CO had gradually increased relaxation rate, thus binding water more tightly. Rheological and microrheological tests suggested the addition of CO with larger MW resulted in much tighter gel network. These results indicated that CO with larger MW improved the quality of MP gel more effectively, which was because CO with larger MW inhibited aggregation of MP to a larger extent, resulting in smaller MP aggregates. Then MP-CO gel with much denser and more homogeneous structure was formed. Besides, MP-CO gel with larger MW of CO had higher content of β-sheet, resulting in MP gel with more ordered structure and better gel quality. Therefore, this study provided theoretical guidance for choosing the appropriate CO in improving texture of high temperature meat products.

Exploring the potential of fibrinogen hydrolysates as enhancers for myofibrillar protein gelation: Insights into molecular assembly behavior

This study explored the use of pig blood fibrinogen hydrolysates, enzymatically hydrolyzed with trypsin and flavorzyme, to enhance myofibrillar protein gels, addressing issues like poor gel strength and water loss in meat products. By incorporating varying concentrations of fibrinogen hydrolysates into myofibrillar proteins, heat-induced gels were prepared. The composite gels showed improved textural properties, rheological characteristics and water-holding capacity. Scanning electron microscopy and atomic force microscopy analyses revealed a uniform, dense surface and an orderly internal structure in the composite gels. The study also noted decreased α-helix and random coil and increased β-sheet and β-turn contents, indicating a more ordered secondary structure. Hydrophobic interactions and disulfide bonds were identified as key factors in enhancing gelation, and a model was proposed to explain these molecular effects. This research demonstrates a potential of fibrinogen hydrolysates to improve quality and structure of myofibrillar protein gels designed for high-quality meat products.

Mechanism of Toona sinensis seed polyphenols inhibiting oxidation and modifying physicochemical and gel properties of pork myofibrillar protein under oxidation system

This research aimed to elucidate how Toona sinensis seed polyphenols (TSSs) inhibited pork myofibrillar protein (MP) oxidation and modified physicochemical and gel properties in the Fenton oxidation system. Our result displayed that TSSs had a lower carbonyl (from 1.38 to 0.59 nmol/mg) and dityrosine contents (from 47.22 to 25.07), and higher free amino content (from 386.99 to 485.00 nmol/mg), followed by ellagic acid (EA) and quercetin-3-O-rhamnoside (QC). Meanwhile, the incorporation of phenolic compounds changed secondary and tertiary structure of proteins and then increased solubility and absolute value of zeta potential, as well as decreased turbidity and average particle size. Molecular docking indicated that MP interacted with EA primarily via hydrogen bonds and hydrophobic interaction, and with QC mostly through hydrogen bonds and electrostatic interaction. Otherwise, the incorporation of EA promoted MP gel to form a honeycomb-like microstructure after oxidation. Therefore, TSSs, EA, and QC could significantly inhibit MP oxidation as well as modify its physicochemical properties, but only EA enhanced its gel properties after oxidation. The results could be useful to improve the comprehensive utilization of plant by-products and provide theoretical references for the role of TSSs in the improvement of meat products.

Co-stabilization effects of gluten/carrageenan to the over-heated myofibrillar protein: Inhibit the undesirable gel weakening and protein over-aggregations

High-temperature (120 °C) sterilization is an indispensable process for manufacturing ready-to-eat surimi products, yet risking the denaturation of their myofibrillar proteins (MP), thus significantly reducing the gelling properties. To resolve this problem, herein, a synergistic co-strengthening strategy was designed. The negatively charged polysaccharide carrageenan (CG) was introduced into MP simultaneously with wheat gluten, followed by 120 °C thermal treatment for 30 min. A substantial enhancement in mechanical strength, up to four times greater (from 9.86 to 42.38 g·cm), was observed for MP gels, which even surpassed that subjected to conventional gelation processes at 90 °C (36.53 g·cm). Gels that were concurrently added with gluten and CG exhibited porous networks, uniform water distribution, and improved water holding capacity. Accordingly, over-aggregation behaviors of MP were restricted, as evidenced by their reduced particle sizes and polymer dispersity index. Other heat-induced protein deteriorations at 120 °C, i.e., changes of secondary structures and disulfide bonding conformations, were also alleviated. By varying the CG types, it was shown that the κ-CG/gluten-added MP achieved highest gel strength, while the ι-CG/gluten combination may better stabilize the moisture in gel networks. This study introduces a co-reinforcement paradigm and scientific insights to the quality improvement of ready-to-eat meat products.

Proteomic analysis revealing mechanisms of κ-carrageenan modulating the gelling properties of heat-induced microbial transglutaminase cross-linked myofibrillar protein gels

The effects of κ-carrageenan (KC, 0.2 %, w/w) on the gelling properties and microstructures of heat-treated myofibrillar protein (MP) gels mediated by various levels (0, 0.1, 0.3, and 0.5 %, w/w) of microbial transglutaminase (TG) were investigated. The results revealed that regardless of TG level, the existence of KC significantly promoted the forming of disulphide bonds but limited the generation of large-sized protein polymers in MP gel treated with TG alone, as well as subsequently enhanced the water retention ability and gel strength of mixed MP gel, especially in the sample adding 0.3% TG and 0.2% KC, which was clearly verified by the forming of more denser and continuous gel network. Moreover, TG-induced changes in protein structure led to the alteration in the protein profiles of different MP gels, and an obvious down-regulation trend of myosin (Q9TV63, Q9TV62, P79293, and Q9TV61) was identified in the TG-0.3 group. Furthermore, liquid chromatography–tandem mass spectrometry analysis demonstrated that TG mainly induces protein crosslinking in the light meromyosin domain of the myosin rod. Meanwhile, in the presence of KC, the crosslinking-site percentage of the TG-0.3 group decreased from 37.7% to 36.2%, indicating that KC potentially reduces TG-induced crosslinking in MP gels. Thus, our findings illustrate the critical mechanisms underlying the modulation of KC on the gelling properties of TG-mediated MP gels at the molecular level, which providing potential guideline for the combined applications of TG and KC in the meat industry.

Influence of droplet size and surface hydrophobicity of soybean protein-based nanoemulsion fillers on the quality of silver carp myofibrillar protein gels

This study investigated the mechanisms underlying the influence of droplet size and emulsifier wettability on gel properties when oil-in-water (O/W) emulsions serve as fillers in myofibrillar protein (MP) gels. Pickering emulsions with varying droplet sizes were prepared using soybean protein isolate (SPI) and SPI-curcumin nanoparticles, then used to construct composite gels. Findings showed that decreased droplet size and increased emulsifier surface hydrophobicity enhanced hydrophobic interactions in the gel, increasing the β-sheet content of MP molecules. Upon the introduction of SPI-Cur-NPs stabilized nanoemulsion (SCNE), the hydrophobic force in the gel was approximately 2.6-fold more remarkable than that of the control, and the β-sheet content increased to 16.51 %. This resulted in a denser mesh framework and more uniform oil droplet distribution, increasing the hardness value from 26.993 g to 41.847 g. Moreover, SCNE addition improved gel antioxidant properties, reducing carbonyl and peroxide levels to 31.82 % and 24.15 % of the control, respectively. These findings offer insights for improving MP-based gel products.

Effect of chitosan on thermal gelling properties of pork myofibrillar protein and its mechanism.

Previous studies have demonstrated that the addition of chitosan can improve the quality and functional properties of meat products. However, the underlying mechanism remains unclear. In this study, the effect and mechanism of the addition of chitosan on the gel properties of myofibrillar protein (MP) were investigated. The results indicated that the gel strength and the water-holding capacity of MP-chitosan gel increased significantly when chitosan was added at 2.5-10 mg mL-1. Myofibrillar protein samples with 10 mg mL-1 added chitosan exhibited the highest elasticity and viscosity during gel formation and strengthening. The addition of chitosan also caused a modification in both the secondary and tertiary structure of MP, resulting in an enhanced exposure of hydrophobic and sulfhydryl groups in comparison with the control. Chitosan inhibited the conversion of immobilized water into free water and the formation of water channels during the thermal gelation process of MP. The denaturation enthalpy (ΔH) of myosin decreased as the concentration of chitosan exceeded 5 mg mL-1. The microstructure showed that the incorporation of chitosan (5-10 mg mL-1) facilitated the formation of compact and well organized MP gel networks. The addition of chitosan can enhance the functional properties of meat protein and facilitate heat-induced gelation, making it a promising ingredient for improving the quality of processed meat products. © 2024 Society of Chemical Industry.

Effect of chickpea protein modified with combined heating and high-pressure homogenization on enhancing the gelation of reduced phosphate myofibrillar protein

The effects of chickpea protein (CP) modified by heating and/or high-pressure homogenization (HPH) on the gelling properties of myofibrillar protein under reduced phosphate conditions (5 mM sodium triphosphate, STPP) were investigated. The results showed that heating and HPH dual-modified CP could decrease the cooking loss by 29.57 %, elevate the water holding capacity by 17.08 %, and increase the gel strength by 126.88 %, which conferred myofibrillar protein with gelation performance comparable with, or even surpassing, that of the high-phosphate (10 mM STPP) control. This gelation behavior improvement could be attributed to enhanced myosin tail–tail interactions, decreased myosin thermal stability, elevated trans–gauche–trans disulfide conformation, strengthened hydrophobic interactions and hydrogen bonding, the uncoiling of α-helical structures, the formation of well-networked myofibrillar protein gel, and the disulfide linkages between the myosin heavy chain, actin, and CP subunits. Therefore, the dual-modified CP could be a promising phosphate alternative to develop healthier meat products.

Meat exudate metabolomics reveals the impact of freeze-thaw cycles on meat quality in pork loins

The aim of this study was to explore the effects of freeze-thaw (FT) cycles on meat quality, myofibrillar protein gelation and emulsification properties, and exudate metabolome changes in pork loins. Meat tenderness improved (P < 0.05), whereas water-holding capacity (WHC), meat color attributes declined (P < 0.05) with FT cycles. Multiple FT accelerated meat lipid and protein oxidations. Decreases in strength and WHC of myofibrillar protein gels with FT cycles were confirmed. Myofibrillar protein emulsions with more FT cycles showed a decrease in the emulsifying activity index (P < 0.001) and larger oil droplets, resulting in poorer storage stability. A total of 501 metabolites were tentatively identified in pork exudates, with 21 metabolites significantly correlated (P < 0.05 and r > 0.6) with meat quality attributes. These results demonstrated the potential of using the metabolomic information from exudates to elaborate on or even predict the FT cycles, or meat quality.

Optimizing gelation properties of mixed meat myofibrillar proteins: investigating the effects of different proportions of beef, pork and chicken on physicochemical, structural and gelation properties.

The gelation properties of myofibrillar protein (MP) directly affect the texture, taste and water-holding capacity (WHC) of meat products. To enhance the gelation properties of single-species meat MP, the present study investigated the influence of different proportions of beef, pork and chicken MP on the physicochemical properties, structure and gelation properties of the MP. The results revealed that, when the proportion reached 5:2:3, the particle size decreases, leading to the maximum decomposition and unfolding of MPs, which exposes a greater number of hydrophobic amino acid residues. These changes promote interactions between protein molecules, especially the unfolding of α-helices and the formation of β-sheets during the heating process, which provides favorable conditions for the formation of protein gels and improves the gel strength and WHC of MP gels. Additionally, scanning electron microscopy revealed that the mixed MP gels are more compact and have more uniform gel networks and pores compared to single-species MP gels. Based on these results, the synergistic effect is induced by the interactions between proteins from different. This research provides a method for the subsequent development of new meat products and improvement of meat product quality, and also lays a theoretical foundation for composite research of proteins from different sources. © 2024 Society of Chemical Industry.

Role of sodium pyrophosphate and catechin in the enzymatic hydrolysis of oxidatively damaged myofibrillar protein gels in vitro: Mechanistic insights

This study investigated the effects of sodium pyrophosphate (SPP) and catechin (C) on the in vitro enzymatic digestion of oxidatively damaged myofibrillar protein (MP) gel. The results indicated that SPP increased the β-sheet content and the gastric digestibility of the MP gel, while C hindered the transition from α-helix to β-sheet structure, leading to decreased digestibility. Notably, neither compound significantly affected intestinal digestibility. Furthermore, SPP and C significantly enhanced the antioxidant activity of MP gel digestion products. Notably, their synergistic hydrolysis products, simulating both gastric and gastrointestinal stages, chelated 91.4 % and 89.1 % of Fe2+ and scavenged 59.4 % and 77.6 % of hydroxyl radicals, respectively. Moreover, the final digestion products of the MP gel treated with SPP and C exhibited the highest content of negatively charged amino acids and absolute Zeta potential values. Overall, this study demonstrated that incorporating SPP and C could positively impact the digestion of oxidatively damaged MP gels.

Tracking protein aggregation behavior and molecular interactions induced by conformational alterations in the formation of myofibrillar protein-Abelmoschus manihot gum mixed gels during heating process

The present study aimed to systematically investigate the effects of different Abelmoschus manihot gum (AMG) concentrations (0–0.5%, w/w) on the formation of myofibrillar protein (MP) gels during heating process (30–80 °C) based on conformational alterations, protein aggregation behavior and molecular interactions. With the increase of temperature, the fluorescence intensity and α-helix content significantly decreased, revealing conformational transition of MP molecular. Dynamic rheological results indicated that MP had completely denatured and formed temporary gel at 50 °C, and completely formed irreversible cross-linked three-dimensional network structure at 80 °C. Moreover, the addition of AMG decreased the fluorescence intensity, as well as induced the transition of MP from α-helix to β-sheet during the whole heating process. Furthermore, AMG addition significantly decreased the turbidity and improved solubility of MP (P < 0.05), especially for at 0.3% AMG concentration, indicating that AMG accelerated the early unfolding and aggregation of MP during heating process. This was verified by the dynamic rheological results. Additionally, hydrophobic interactions and disulfide bonds were the main molecular forces to induce the formation of MP-AMG mixed gel. Therefore, our present results provided the new insights into the formation of MP-AMG mixed thermal-induced gel, and also contributed to the practical application of AMG in meat processing.

Influence of NaCl and phosphate on gelation properties of chicken breast myofibrillar protein gels and its application to in vitro digestion model

To investigate the combination effect of sodium chloride and phosphates on chicken breast myofibrillar proteins, MP gels containing various molarity of NaCl (0.15, 0.30 and 0.45 M) and phosphate (0 and 0.05 M) were prepared, their rheological properties were characterized, and applied to an in vitro digestion model. MP mixture containing 0.45 M NaCl and 0.05 M phosphate had the highest viscosity. The gel strength and cooking yield of MP gels was improved by increasing of molarity of NaCl. As NaCl concentration in MP increased, sulfhydryl levels decreased, while disulfide levels increased. As NaCl and phosphate levels increase, MP gels become denser and porosity decreases, which may reduce protein digestibility. In SDS-PAGE, protein bands from MP gels containing low NaCl levels (≤ 0.30 M) degraded more rapidly during in vitro digestion. These results may support the need for the meat industry to develop low-salt meat products with improved digestibility. KeywordsChicken,Myofibrillar protein,NaCl,Phosphate,Rheological properties,In vitro digestion

Understanding the textural enhancement of low-salt myofibrillar protein gels filled with pea protein pre-emulsions through interfacial behavior: Effects of structural modification and oil phase polarity

This study investigated the effects of pea protein pre-emulsions containing triglyceride- or diglyceride-oil on the emulsifying and gelling properties of low-salt myofibrillar protein (MP). Pea protein isolates treated with pH12-shifting (PPIpH) or ultrasonication (PPIU) demonstrated superior initial interfacial adsorption and higher final interfacial pressure than native pea protein. Within MP/PPI blends, an increased ratio of MP led to a decrease in interfacial pressure, while simultaneously enhancing film elasticity at both polar and non-polar interfaces. Polar diglyceride promoted protein adsorption and fostered interfacial interactions between modified pea proteins and MP, enhancing the cross-linking of transglutaminase (TG) in the composite emulsion gels. Combining diglyceride-type PPIU and PPIpH emulsions with TG increased gel strength to 0.58 N and 0.63 N, respectively, from an initial 0.33 N, yielding a denser protein network with uniformly dispersed oil droplets. Therefore, the utilization of diglyceride and modified PPI can serve as structural enhancers in comminuted meat products.

Molecular mechanism of acetylated distarch phosphate with pea protein isolate to improve the gel quality of myofibrillar protein gel

AbstractIt is crucial to improve the gel properties of myofibrillar protein (MP) in the production of surimi products. This study investigated the effects of combining acetylated distarch phosphate (ADSP) with pea protein isolate (PPI) as exogenous additives on the physicochemical properties of Larimichthys crocea MP gel and elucidated the molecular mechanisms underlying the improvement of MP gel quality. The results showed that the mixture of 3% ADSP and 1% PPI increased the MP gel strength to 2.1 times and water holding capacity to 1.8 times. The rheological properties during thermal‐induced gelation were improved, and the surface roughness of gel microstructure was reduced. The protein conformation was stabilized by enhancing surface hydrophobicity and sulfhydryl content, and the gels showed trends of decreasing α‐helix and increasing random coils. Correlation and cluster analysis showed that physicochemical properties of MP gels were closely related to the changes of protein structure and the denaturation of active groups. The molecular interaction between ADSP, PPI, and MP and the mechanism of enhancing the properties and functions of MP gel were further clarified. These findings highlight the feasibility of ADSP–PPI as an effective strategy to improve the quality of fish MP gel.