Myofibrillar Proteins Research Articles

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.

Procurement and Preservation of Neonatal Porcine Cardiac Tissue.

The porcine and human heart are remarkably similar in cardiac physiology and biochemistry. Translational research involving the porcine biomedical model is becoming increasingly applicable for the study of human cardiac function in health and disease. Presently, few protocols exist for collecting experimentally viable cardiac tissue from large animal models, particularly during neonatal maturation. To address this deficiency, we have developed a technique to procure and preserve ventricular tissue from neonatal piglets at day 3 (n=4) and day 30 (n=6) post-partum. Piglets were subjected to a strict sedation, anesthesia, and analgesia regimen. During surgery, cardiopulmonary indices of electrocardiogram, heart rate, systolic and diastolic blood pressure, respiration rate, peripheral O2 saturation, and end-tidal CO2 were monitored continuously to ensure normal cardiac function. Prior to cardiectomy, each heart was perfused with an intravenous administration of heparin (10 ml/kg) and ice-cold Custodiol HTK cardioplegia solution (10 ml/kg). After cardiac explantation, myocardial samples (dimensions: 1 x 1 x 1 cm) were dissected from the left and right ventricles and snap-frozen in liquid nitrogen. Analysis via SDS-PAGE and densitometry demonstrated that myofibrillar proteins are stable and undegraded. Western Blots showed full expression of protein. These results suggest that the detailed cardiac tissue procurement technique preserves the experimental viability of the cardiac tissue and prevents the degradation of myofibrillar proteins.

Molecular determinants of skeletal muscle force loss in response to 5days of dry immersion in human.

Astronauts in Earth's orbit experience microgravity, resulting in a decline of skeletal muscle mass and function. On Earth, models simulating microgravity have shown that the extent of the loss in muscle force is greater than the loss in muscle mass. The reasons behind this disproportionate loss of muscle force are still poorly understood. In the present study, we hypothesize that alongside the loss in skeletal muscle mass, modifications in the expression profile of genes encoding critical determinants of resting membrane potential, excitation-contraction coupling and Ca2+ handling contribute to the decline in skeletal muscle force. Healthy male volunteers (n=18) participated in a 5-day dry immersion (DI) study, an Earth-based model of simulated microgravity. Muscle force measurement and MRI analysis of the cross-sectional area of thigh muscles were performed before and after DI. Biopsies of the vastus lateralis skeletal muscle performed before and after DI were used for the determination Ca2+ properties of isolated muscle fibres, molecular and biochemical analyses. The extent of the decline in force, measured as maximal voluntary contraction of knee extensors (-11.1%, P<0.01) was higher than the decline in muscle mass (-2.5%, P<0.01). The decline in muscle mass was molecularly supported by a significant repression of the anabolic IGF-1/Akt/mTOR pathway (-19.9% and -40.9% in 4E-BP1 and RPS6 phosphorylation, respectively), a transcriptional downregulation of the autophagy-lysosome pathway and a downregulation in the mRNA levels of myofibrillar protein slow isoforms. At the single fibre level, biochemical and tension-pCa curve analyses showed that the loss in force was independent of fibre type (-11% and -12.3% in slow and fast fibres, respectively) and Ca2+ activation properties. Finally, we showed a significant remodelling in the expression of critical players of resting membrane potential (aquaporin 4: -24.9%, ATP1A2: +50.4%), excitation-contraction coupling (CHRNA1: +75.1%, CACNA2D1: -23.5%, JPH2: -24.2%, TRDN: -15.6%, S100A1: +27.2%), and Ca2+ handling (ATP2A2: -32.5%, CASQ1: -15%, ORAI1: -36.2%, ATP2B1: -19.1%). These findings provide evidence that a deregulation in the expression profile of critical molecular determinants of resting membrane potential, excitation-contraction coupling, and Ca2+ handling could be involved in the loss of muscle force induced by DI. They also provide the paradigm for the understanding of muscle force loss during prolonged bed rest periods as those encountered in intensive care unit.

Improved gel properties of Nemipterus virgatus myofibrillar protein emulsion gel by Konjac glucomannan incorporation: Insight into the modification of protein conformation

This study aimed to improve the gel properties of emulsion gels prepared by physical complex of fish protein and polysaccharide. The effects of Konjac glucomannan (KGM) on the structure, emulsibility of Nemipterus virgatus myofibrillar protein (MP), and the gel properties of heat-induced MP emulsion gel were investigated. The results indicated KGM modification facilitated the unfolding of MP, exposing more tryptophan and hydrophobic groups, thereby improving the wettability and emulsifying activity of MP/KGM mixtures. The interactions between MP and KGM molecules were mainly non-covalent hydrogen bonding and hydrophobic interaction. The MP/KGM mixtures exhibited superior adsorption properties at the oil-water interface, particularly with 0.5 % KGM addition, thus forming small and evenly distributed oil droplets. Besides, the curves of viscosity, G' and G" of MP/KGM emulsions climbed continuously with the increased KGM concentration. The presence of KGM, especially the medium amount (0.5 %), was conducive to the translation of α-helix into β-sheet and the formation of more dense and ordered gel network structure, thereby enhancing the gel properties of MP/KGM emulsion gels.

Effect of Shikimic Acid on Oxidation of Myofibrillar Protein of Duck Meat During Heat Treatment.

The myofibrillar protein (MP) of duck meat is prone to excessive oxidation during thermal processing, resulting in a decline in its overall quality. In this paper, the effect of shikimic acid on the oxidative structure of duck muscle fibrin was studied. The findings showed that, at a mass ratio of 1:50,000 (g/g) between shikimic acid and MP, the carbonyl content of MP was reduced by 74.20%, while the sulfhydryl content was increased by 73.56%. MP demonstrated the highest denaturation temperature, whereas its thermal absorption was the lowest. The percentage of α-helixes and β-sheets increased by 16.72% and 24.74%, respectively, while the percentage of irregular structures decreased by 56.23%. In addition, the surface hydrophobicity index of MP exhibited a significant decrease (p < 0.05), while there was a significant increase in its free radical-scavenging ability (p < 0.05). Molecular fluorescence spectrum analysis showed that shikimic acid could bind to MP, altering the internal environment of MP and enhancing its thermal stability. FTIR analysis showed that shikimic acid could enhance the distribution of protein particle sizes by reducing irregular structures, the proportion of β-rotation, and the degree of protein aggregation. It is hoped that this research can offer scientific support for improving meat processing technology.

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.

Advances in Research on the Improvement of Low-Salt Meat Product Through Ultrasound Technology: Quality, Myofibrillar Proteins, and Gelation Properties.

The high sodium content in meat products poses health risks to consumers and does not align with modern green and healthy living standards. Current strategies for directly reducing the sodium content in meat products are limited by their negative impact on the sensory or quality attributes of the products. In recent years, there has been great interest in applying ultrasound technology to reduce sodium content. This paper discusses the advantages and disadvantages of current mainstream strategies for reducing the sodium content in meat products, as well as the potential mechanisms by which ultrasound-assisted marination improves the quality of low-salt meat products. The main findings indicate that ultrasound, through its cavitation and mechanical effects, facilitates the transition of proteins from stable insoluble aggregates to stable soluble complexes, exposing more hydrophilic groups and, thus, enhancing protein solubility. At the same time, ultrasound promotes a greater number of proteins to participate in the formation of interfacial layers, thereby increasing emulsifying activity. Furthermore, ultrasound treatment promotes the interaction between proteins and water, leading to partial unfolding of protein chains, which allows polar residues to more readily capture water in the gel, thereby improving the water-holding capacity of the gel. These effects will contribute to the formation of high-quality low-salt meat products. However, variations in the frequency, intensity, and duration of ultrasound treatment can lead to differing effects on the quality improvement of low-salt meat products.

Research Progress on the Mechanism of the Impact of Myofibrillar Protein Oxidation on the Flavor of Meat Products.

Myofibrillar proteins primarily consist of myosin, actin, myogenin, and actomyosin. These proteins form complex networks within muscle fibers and are crucial to the physical and chemical properties of meat. Additionally, myofibrillar proteins serve as significant substrates for the adsorption of volatile flavor compounds, including aldehydes, alcohols, ketones, and sulfur and nitrogen compounds, which contribute to the overall flavor profile of meat products. A series of chemical reactions occur during the processing, storage, and transportation of meat products. Oxidation is one of the most significant reactions. Oxidative modification can alter the physical and chemical properties of proteins, ultimately impacting the sensory quality of meat products, including flavor, taste, and color. In recent years, considerable attention has been focused on the effects of protein oxidation on meat quality and its regulation. This study investigates the impact of myofibrillar protein oxidation on the sensory attributes of meat products by analyzing the oxidation processes and the factors that initiate myofibrillar protein oxidation. Additionally, it explores the control of myofibrillar protein oxidation and its implications on the sensory properties of meat products, providing theoretical insights relevant to meat processing methods and quality control procedures.

Effect of ultrasound treatment on the emulsion gelling properties of PSE-like chicken myofibrillar protein

ABSTRACT The effects of ultrasound treatment (20 kHz, 0, 150, 300, 450, 600 W, 6 min) on the gel properties of PSE (pale, soft, and exudative)-like chicken myofibrillar protein (MP) emulsion gels were studied. When the ultrasound power increased from 0 W to 600 W, the water-holding capacity (WHC) and gel strength of PSE-like MP emulsion gel increased by 45.01% and 37.5%, respectively (p < 0.05), the storage modulus (G’) is increased and free water began to move in the direction of immobilized water, changed hydrogen bonds to other types of intermolecular force. Fourier transform infrared spectroscopy (FTIR) showed that ultrasound treatment promoted to the transformation from α-helix to β-sheet. The microstructure showed that the emulsion gel of MP after ultrasound treatment had a dense network structure. Ultrasound treatment effectively improved the gel properties of PSE-like chicken MP emulsion gels, which provides a new idea for improving the gel properties of PSE-like chicken protein.

Metabolic kinetics and muscle and brain health markers in older adults, and the role of age and presence of chronic morbidities: A large cross-sectional cohort study

Background & aimsOlder adults are at risk for muscle and cognitive function decline during advanced aging, but the underlying metabolic mechanisms and the role of aging-associated chronic morbidities remain unclear. In the present study, we examined whether protein and amino acid kinetics in older adults with and without chronic morbidities are different when 50-70 and 70-90 of age and related to markers of muscle and brain health declines. MethodsIn a large cross-sectional observational study, 575 older adults from 12 trials (2014-2022) were stratified based on their age (50-70y vs. 70-95y) and the presence of chronic morbidities. The main outcomes were whole-body production (WBP) and interconversions of amino acids by stable amino acid tracers, body composition, and muscle and cognitive performance. Additionally, the association between metabolic markers and muscle and brain health was assessed. ResultsOverall lower muscle strength, muscle and fat mass, and cognitive function (p<0.03), but no mood disturbances, were found in 70-95y compared to 50-70y older adults. Presence of morbidities was associated with lower muscle strength and mass, and cognitive function, but higher visceral adipose tissue, and mood disturbances (p<0.05). Aging was associated with suppressed WBP of most amino acids, de novo arginine production, and net protein breakdown, but higher myofibrillar protein breakdown (p<0.007). Presence of morbidities was associated with lower WBP of glutamine, glutamate, histidine, isoleucine, phenylalanine, tyrosine, and net protein breakdown, and higher WBP of valine and taurine (p<0.04). Age showed significant negative correlations with WBP of nearly all amino acids, de novo arginine production and net protein breakdown (r: [-0.407, -0.136], p<0.01) but a positive correlation with WBP of myofibrillar protein breakdown (r=0.133, p=0.009). Lean mass showed positive correlations with de novo arginine production and net protein breakdown and WBP of all amino acids except for isoleucine (r: [0.16, 0.799], p<0.005). Worse cognitive performance was positively associated with WBP of tau-methylhistidine and taurine (r: [0.13, 0.141], p<0.04), but negatively associated with WBP of glycine, valine, and net protein breakdown (r: [-0.222, -0.135], p<0.05). ConclusionComprehensive phenotyping of a large group of older adults revealed differences in metabolic health in response to advanced aging and chronic morbidities. Poor muscle health accompanied by advanced aging was associated with overall metabolic downregulation, except for enhanced myofibrillar (muscle) protein breakdown. Presence of chronic morbidities was further associated with disturbed muscle health, mood, arginine, and taurine pathways, and higher visceral adipose tissue. Therefore, different phenotypes among older adults need to be considered when evaluating therapeutic approaches to improve muscle and brain health.

Ethanolic duea ching extract in combination with microbial transglutaminase: Strengthening effect on mince gel and cross-linking of myofibrillar proteins from Indian mackerel

Surimi or fish mince gel are popular seafood products worldwide. Lean fish are commonly used as raw material, while dark fleshed fish, especially Indian mackerel, has high fat content and dark color associated with poor gel quality. To improve gel strength, plant extract, particularly from duea ching (Ficus botryocarpa Miq.), rich in polyphenols and calcium could be used as natural protein cross-linker to strengthen gel network. Effect of ethanolic duea ching extract (EDCE) at varying levels in the absence and presence of microbial transglutaminase (MTGase) on gel property of Indian mackerel mince gel prepared from fillets pre-washed for different times (1 and 3 times) was studied. Heat-induced aggregation of myofibrillar protein (MP) from Indian mackerel fillets under different conditions was also investigated. Mince gel prepared from fillets pre-washed for 3 times added with 0.10 % EDCE and 0.5 unit/g of MTGase (3-PWM-MT-0.10) showed the highest breaking force, deformation and textural properties (P < 0.05). Lower autolysis of mince gel was obtained when EDCE, MTGase or in combination were added. However, addition of ECHE decreased whiteness of mince gel, particularly at higher concentrations (P < 0.05). Electrophoretic images revealed the disappearance of myosin heavy chain when MTGase or EDCE in conjunction with MTGase was incorporated. Addition of 0.10 % EDCE, MTGase or both could induce aggregation and enhance setting phenomenon of MP solution as indicated by higher absorbance at 660 nm and storage modulus (G′), respectively. Based on microstructure study, 3-PWM-MT-0.10 had more compact, finer and interconnected structure than other gels. Therefore, the use of EDCE and MTGase at the appropriate levels could be used for improving quality of mince gel from pre-washed Indian mackerel fillets.

Cryoprotective effect of magnetic field-assisted freezing in combination with curdlan on myofibrillar protein of Litopenaeus vannamei: Oxidative aggregation, protein structure and thermal stability

To counteract the negative effects of conventional freezing methods on frozen surimi products, the present study investigated the effects of magnetic field (MF) freezing in combination with different amounts of curdlan (CUR) on oxidative denaturation, structural alterations, and thermal stability of myofibrillar protein (MP) in shrimp surimi. The results indicated that the intervention of magnetic fields alone improved the quality of frozen muscle proteins. Under the dual intervention of magnetic field-assisted freezing and CUR, small ice crystals formed with MF6 treatment resulted in significantly lower solubility, turbidity, and mean particle size than the control group (p < 0.05). Moreover, the oxidation of MP was also significantly slowed down by inhibiting the formation of hydrophobic groups and carbonyl groups, maintaining a high content of sulfhydryl groups. MF6 also exhibited a high Ca2+-ATPase activity. The α-helix content, the increase in fluorescence intensity under this condition also tend to make the secondary and tertiary structures of myofibrillar protein more stable. Meanwhile, electrophoretic profiles and CLSM showed that this condition maintains the integrity of the MP. In addition, the MF6 samples also had high protein thermal stability. However, excess CUR reduces the excellence of MP cryoprotection. As a result, MF6 has better protection and improvement effects on protein function, structure and thermal stability, and CUR was also found to have the potential for cryoprotectant development.

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.

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.

Revealing protein aggregation behaviour and dispersion properties induced by molecular interactions between sucrose esters and myofibrillar protein in an aqueous phase system

The effects of sucrose esters (SE) with varying hydrophilic-lipophilic balance (HLB) values (SE 11, 13, 15) and different concentrations (0.01, 0.1, 1.0 mM) on the dispersion properties and structure of myofibrillar proteins (MPs) in the aqueous phase were investigated. The results demonstrated that the SE 11 and SE 13 reduced the particle size and enhanced the distribution uniformity of the MPs. All of the SE exhibited a slight reduction in the ζ-potential absolute values of the MPs. Meanwhile, the SE 11 significantly reduced the turbidity of the MPs, especially in the 0.1 mM group. Macroscopic and microscopic images showed that the optimum dispersion state was in the SE 11–0.1 group. Furthermore, the interactions between SE and MPs exerted a significant impact on the proteins structure. The SE 13 and SE 15 caused significant changes, which presented concentration correlation, in the tertiary and secondary spatial structures of the MPs. Nevertheless, slight structural changes were observed in MPs with different SE11 concentrations. The SE did not alter the molecular weight of the MPs, i.e. it did not induce irreversible aggregation, nor degradation of the proteins. These results were verified by the surface hydrophobicity, UV–Vis spectroscopy, intrinsic fluorescence, circular dichroism, and SDS-PAGE. Molecular docking simulation showed that hydrophobic interactions and hydrogen bonds were the main interaction force between SE 11 and MPs. Therefore, our findings provided meaningful insights into the dispersion state of the MPs aqueous containing SEs and contributed to the practical application of non-ionic surfactants in meat protein processing.

Ultrasound treatment improved gelling and emulsifying properties of myofibrillar proteins from Antarctic krill (Euphausia superba)

Antarctic krill is a promising source of marine proteins with abundant biomass and excellent nutritional profile, but has poor technological properties. Ultrasonic treatment at power levels of 0, 100, 200, 300, 400 and 500 W was applied to improve the technological properties of Antarctic krill meat, and the changes in physicochemical properties of myofibrillar proteins (MPs) were investigated. The results indicated that proper ultrasonic treatment significantly improved the gelling properties of Antarctic krill meat, in terms of a more uniform and stable gel texture and better water holding capacity, which were related to better cross-linking of MPs. Ultrasonic treatment promoted the conversion of MPs’ secondary structures from α-helix and random coil to β-sheet and β-turn, thereby making the molecular structure soft and loose. In addition, at tertiary structure level, ultrasonic treatment exposed the hydrophobic groups and sulfhydryl groups within MPs, thereby improving the emulsifying properties by changing the intermolecular interactions and interface properties. Furthermore, the particle size of MPs decreased and exhibited a more uniform distribution, aligning with the enhanced interactions observed between MPs and oil. These results provide an insight into the efficient development of Antarctic krill by elucidating how the ultrasonic treatment improves the gelling and emulsifying properties based on structure modulation of myofibrillar proteins.

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.

Effect of bacterial fermentation on the ability of myofibrillar proteins to bind esters and its potential mechanism: Based on protein metabolism and structural changes

The effect of fermentation strains (Lactiplantibacillus plantarum CQ01107 and Staphylococcus simulans CD207) on the binding properties of porcine myofibrillar proteins (MPs) to esters was investigated from two perspectives: metabolism degree and structural alterations. Results demonstrated that S. simulans could reduce the particle size and α-helix content of MPs, while simultaneously increasing the absolute zeta potential and active sulfhydryl content. This process decreased protein aggregation and facilitated the unfolding of MPs, thereby enhancing their binding to esters. Conversely, L. plantarum showed limited promotion, which might be related to its robust acid production and protein hydrolysis capacities. In addition, ethyl octanoate, with a longer carbon chain length, was found to have the highest binding capacity to MPs (28.38 %–41.59 %). Molecular docking results further revealed that the binding of the four esters to MPs was spontaneous, with ethyl octanoate exhibiting the lowest binding energy to MPs (−5.635 kcal/mol). The primary forces involved in the binding of the four selected esters to MPs were hydrophobic interactions, hydrogen bonding, and van der Waals forces. These findings can provide new insights into the mechanisms by which fermentation strains influence flavor formation in fermented foods.