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This study investigated the effects of ethanol, 1,2-propanediol, and glycerol on the structure and aggregation behavior of silver carp (Hypophthalmichthys molitrix) myosin. All alcohols induced extensive alteration in the tertiary structure of myosin. Both ethanol and 1,2-propanediol further promoted an increase in the content of β-sheets in myosin and induced myosin aggregation. While glycerol had almost no impact on the secondary structure of myosin. Molecular dynamics simulations revealed that increasing the concentration of ethanol and 1,2-propanediol affected the overall structural changes in the myosin heavy chain (MHC), while glycerol exerted a more pronounced effect on the MHC tail when compared to the MHC head. Disruption of the hydration layers induced by ethanol and 1,2-propanediol contributed to local structural changes in myosin. Glycerol at a concentration of 20% induced the formation of a larger hydration layer around the MHC tail, which facilitated the stabilization of the protein structure. [Display omitted] • Ethanol and 1,2-propanediol promoted the formation of β-sheets in myosin. • Glycerol had no discernible effect on the myosin secondary structure. • The daisy wheel-like myosin oligomers were observed in ethanol at 10% concentration. • The disruption of hydration layers contributed to myosin structural changes. • 20% glycerol stabilizes the myosin structure by promoting the hydration layers. [ABSTRACT FROM AUTHOR]

This study investigated the mechanism of ethanol enhancing the gel properties of heat-induced silver carp (Hypophthalmichthys molitrix) surimi gels. The presence of ethanol reduced the thermal stability of surimi protein, and the denaturation temperature of myosin decreased by approximately 7 °C in the presence of 5% ethanol. The gel strength, textural characteristics, and storage modulus (G′) of the gels improved depending on ethanol levels, while the water holding capacity (WHC) remained steady. Adding ethanol stabilized the α-helix and β-sheet in the protein structures of the gels, reducing the content of the random coil. Appropriate heat denaturation rate induced by ethanol increased protein cross-linking, which may relate to forming more disulfide bonds. In addition, ethanol incorporation promoted the formation of more isopeptide bonds catalyzed by transglutaminase (TGase) and weakened the hydrolysis of surimi proteins by cathepsins, further enhancing the formation of a dense and uniform gel network. • Ethanol promoted protein cross-linking and enhanced the gel properties. • The enhancement mechanism of ethanol on the gel performance was investigated. • Ethanol increased the ordered secondary structure of proteins during heating. • Proper thermal denaturation rate of proteins allows more disulfide bonds to form. • Ethanol promoted more isopeptide bond formation and weakened protein hydrolysis. [ABSTRACT FROM AUTHOR]

Chronic liver disease inevitably progresses to liver cirrhosis, significantly compromising patients' overall survival and quality of life. However, a glimmer of hope emerges with the emergence of mesenchymal stem cells, possessing remarkable abilities for self-renewal, differentiation, and immunomodulation. Leveraging their potential, MSCs have become a focal point in both basic and clinical trials, offering a promising therapeutic avenue to impede fibrosis progression and enhance the life expectancy of individuals battling hepatic cirrhosis. This comprehensive review serves to shed light on the origin of MSCs, the intricate mechanisms underlying cirrhosis treatment, and the cutting-edge advancements in basic and clinical research surrounding MSC-based therapies for liver cirrhosis patients. • Liver cirrhosis is the final stage of many chronic liver diseases. • Mesenchymal stem cells (MSCs) have paracrine, anti-fibrotic, anti-oxidative stress, and immunomodulatory effects, making them a potential treatment option for liver cirrhosis. • MSC-EVs, gene modification, hypoxia, preconditioning with cytokines or growth factors, and combination therapy can enhance the therapeutic effect of MSCs in treating liver cirrhosis. • Clinical trials have proven MSCs' safety and effectiveness in treating liver cirrhosis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fractions of plant ash (PA) varied in pH, monovalent and divalent cations. • Divalent cations in plant ash induced gelation of Premna microphylla turcz (PMT). • Higher concentration of plant ash weakened the gelation of PMT via increased pH. • Solutions to increase safety of a traditional food production were explored. In order to elucidate the gelling mechanism of Premna microphylla turcz (PMT) induced by plant ash (PA), PA was fractionated into supernatant (PA-S) and precipitation (PA-P) and added to the PMT suspension, respectively. The effects of different concentrations (1–9%) and fractions (PA, PA-S, PA-P) of PA suspension on the gel properties were studied. Results showed that the electrical conductivity, content of monovalent cations, pH were higher in PA-S than PA-P. Both the PA-S and PA-P fractions induced the gelation of PMT (except for the low concentration at 1% for PA-S), and the PA-P-PMT gels showed much higher gel strength and hardness than PA-S-PMT gels. With increased concentration, the gel strength increased in PA-P-PMT, but decreased in PA-S-PMT. A hypothesis for the gelation of PMT induced by PA was proposed: the divalent cations in PA bind to carboxyl group in pectin and form gels; when higher content of PA is added, a higher pH leads to extensive dissociation of carboxyl groups thereby increases the electrostatic repulsion between pectin chains, which ultimately weakens the gelling forces. This study can provide theoretical support for further optimization of the traditional processing of PMT gels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Glutamic acid promoted the aggregation of zein. • The secondary structure of zein changed by the addition of glutamic acid. • Glutamic acid promoted the adsorption of zein on the surface of oil droplets. • Hydrophobic and electrostatic interaction were the main driving force of ZCPs. In this study, glutamic acid and zein were utilized to prepare colloidal nanoparticles as stabilizers for Pickering emulsions. The effect of the ratio of glutamic acid to zein on the stability, zeta potential, particle size, morphology, and structure of colloidal nanoparticles was studied. The results showed that zein and glutamic acid combined in the form of noncovalent bonds, which changed the characteristics of the zein. In addition, colloidal particles aggregation was induced by glutamic acid, which altered the distribution of droplets in the emulsion, and increased the adsorption of proteins on the surface of the oil droplets, as reflected by the analysis of the size, microstructure, rheological behaviours, and driving force of the Pickering emulsion. Hydrophobic interactions and electrostatic interactions were the main driving forces for the formation of colloidal particles, which was determined by driving force analysis and the change of the zeta potential. [ABSTRACT FROM AUTHOR]

• Ordered structures of myosin were converted to disordered structures by L-Arg. • The effect was more obvious on rod-rod cross-linking than head-head aggregation. • Increasing pH induced by L-Arg increased the electrostatic repulsion of myosin. • The cationic L-Arg interacted with anionic groups on the myosin at neutral pH. • Heat-induced phase separation of myosin was ameliorated by L-Arg. This investigation aimed to study the potential mechanism of L-arginine (L-Arg) on the heat-induced phase separation phenomenon of myosin from the perspective of conformational changes of myosin. L-Arg ameliorated the phase separation of myosin after a two-step heating procedure via suppression of heat-induced aggregation of myosin. The effect of L-Arg on the heating of myosin at high temperatures (75–85 °C) was more pronounced than that in the setting stage (35–45 °C), suggesting that the ameliorative effects of L-Arg on the heat-induced phase separation of myosin are mainly attributed to the inhibition of rod-rod cross-linking between denatured myosin molecules. Additionally, L-Arg without pH modification exhibited an increased ability to suppress the gelation of myosin compared with pH modification, indicating that both pH effects and the particular structure of L-Arg play noticeable roles in the suppression of myosin gelation. Far-UV circular dichroism, intrinsic fluorescence spectroscopy and differential scanning calorimetry demonstrated that L-Arg induced the absence of ordered secondary structures of myosin molecules, especially β-sheets, and thus generated a looser protein structure, which may represent the dominant suppression mechanisms of L-Arg on the heat-induced aggregation of myosin. This work provided support for the use of L-Arg as a food additive, and the results of this study will be attractive to the meat and beverage products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oleogel improved low-salt surimi texture with better water retention. • Oleogel addition reduced surimi gel's digestibility due to high cross-linking. • Surimi gel digestive solutions' antioxidant properties were improved by oleogel. • Lower-molecular weight peptides were produced after composite surimi digestion. To improve nutritional health, a low-salt (0.5 %) silver carp (Hypophthalmichthys molitrix) surimi gel with α-tocopherol, soybean oil, and glyceryl monostearate oleogel was fabricated and evaluated for textural qualities, lipid oxidation, and in-vitro digestion analysis. Based on the texture profile analysis, gel strength, water holding capacity (WHC), rheological, protein secondary structure, and microstructural examination, 5 % oleogel addition to low-salt surimi exhibited similar physicochemical properties to regular-salt surimi gels. By crosslinking myosin and filling protein network voids, the oleogel increased surimi gel density. Increasing oleogel content improved the physicochemical qualities of heat-induced surimi, causing protein aggregation during digestion and reducing digestibility. The presence of oleogel altered protein secondary structure, reducing α-helix content and increasing β-sheet and other structures, enhancing WHC and gel strength of low salt surimi. Adding oleogel improved the antioxidant activity of digestive solutions. This study will help understand myosin-oleogel interaction and the development of sustainable and nutritious surimi-based foods. [ABSTRACT FROM AUTHOR]

The suppression mechanism of l -arginine (Arg) in fish myosin heat-induced aggregation was investigated in this work. The hydrodynamic radius determined by dynamic light scattering (DLS) and the turbidity of a myosin solution decreased in a dose-dependently manner with Arg after heating, especially in a solution without pH modification (P < 0.05). The surface hydrophobicity of myosin exhibited the same trend as that for hydrodynamic radius and turbidity (P < 0.05). The myosin secondary structures clearly changed with Arg concentration during heating (P < 0.05). These results demonstrate that positively-charged Arg could form ionic interactions with negatively charged myosin, as well as promote repulsion between myosin molecules induced by higher pH values. Furthermore, the resultant hydrogen bonding observed indicated that, in addition to Arg having ionic linkage effects, the specific structure of Arg played an important role in the suppression of myosin aggregation. Essentially, Arg markedly disturbed the hydrogen bonds of the myosin backbone and formed new hydrogen bonds with myosin molecules via two amino groups (-NH 2), which are part of the guanidinium moiety of Arg, preferentially hydrogen bonding with the backbone carbonyl oxygen atoms of myosin molecules. This work provides support for using Arg as an additive to modify the texture of fish products to produce liquid and semiliquid food suitable for the elderly consumers in an aging society. Image 1 • Arg with/without pH modification suppressed the heat-induced aggregation of myosin. • Positively-charged Arg could form ionic attraction with negatively-charged myosin. • Higher pH values induced by Arg could promote repulsion between myosin molecules. • Guanidinium of Arg is a critical but not the only decisive factor. • Two amino groups of Arg preferentially hydrogen bonded with oxygen atoms of myosin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Myofibrillar proteins shifted to a more acidic isoelectric point upon oxidation. • Oxidation led to decreased or increased net charges of proteins depending on pH. • Dye-binding between proteins and differently charged dyes was investigated. • Oxidation-induced change in net charge is driving force affecting the dye-binding. In order to study the effect of oxidation on the dye-binding behavior of myofibrillar proteins, selected dyes with different charges (positively charged Sarfarin O (SO), neutral bromophenol blue (BPB), and negatively charged Orange G (OG)) were incubated with myofibrils oxidized by the Fenton system with H 2 O 2 (10 mM). Upon oxidation, loss of free thiols, formation of carbonyls, particle size, and hydrophobicity of myofibrillar proteins (MPs) increased. The absolute value of Zeta-potential increased by 14.48 % after oxidation, the myofibrillar proteins shifted to a more acidic isoelectric point (pI) upon oxidation. Oxidation decreased net positive charges of myofibrillar protein and the binding ability of MPs towards OG in the environment with pH less than pI and the affinity of MPs towards SO in the environment with pH more than pI were thus increased. Here we propose a hypothesis that oxidation-induced change in net charges is the driving force affecting the amount of protein-bound dye. This paper aims to examine the effect of oxidation on the net charges of myofibrillar proteins and to provide insight into the mechanism of oxidation-induced changes in protein-bound dyes. [ABSTRACT FROM AUTHOR]

Muscle protein stability during freeze-thaw (F-T) cycles was investigated with tilapia cultured in recirculating aquaculture systems (RAS) and traditional aquaculture in ponds (TAP). This study found that fatty acids (eg., palmitic acid) were enriched in TAP, while antioxidants (eg., glutathione) were enriched in RAS. Generally, proteins in the RAS group exhibited greater stability against denaturation during the F-T cycle, suggested by a less decrease in haem protein content (77% in RAS and 86% in TAP) and a less increase in surface hydrophobicity of sarcoplasmic protein (63% in RAS and 101% in TAP). There was no significant difference in oxidative stability of myofibrillar protein between the two groups. This study provides a theoretical guide for the quality control of tilapia cultured in RAS during frozen storage. [Display omitted] • Muscle composition of tilapia from different aquaculture system was analyzed. • Metabolomics suggested an enrichment of antioxidants in RAS fish muscle. • Proteins in RAS group had greater stability during the freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

Chronic Liver fibrosis may progress to liver cirrhosis and hepatocellular carcinoma (HCC), hence cause a substantial global burden. However, effective therapies for blocking fibrosis are still lacking. Although mesenchymal stem cells (MSCs) have been proven beneficial to liver regeneration after damage, the underlying mechanism of their therapeutic effects are not fully understood. Oxidative stress and mitochondrial functionality alteration directly contributes to the hepatocyte apoptosis and development of liver fibrosis. This study aims to elucidate the mechanism by which hUC-MSC alleviates liver fibrosis and mitochondrial dysfunction. RNA-sequencing was performed to characterize the transcriptomic changes after implantation of hUC-MSCs in mice with liver fibrosis. Next, western blot, RT-PCR, immunohistochemical and immunofluorescence staining were used to evaluate the expression of different genes in vitro and in vivo. Additionally, mitochondrial morphological and dynamic changes, ROS content, and ATP production were examined. Slc25a47, a newly identified liver-specific mitochondrial NAD+ transporter, was notably reduced in CCl 4 -treated mice and H 2 O 2 -stimulated hepatocytes. Conversely, hUC-MSCs increased the Slc25a47 expression and NAD+ level within mitochondria, thereby enhanced Sirt3 protein activity and alleviated mitochondrial dysfunction in the liver. Furthermore, Slc25a47 knockdown could partially abrogate the protective effects of hUC-MSCs on H 2 O 2 -induced mitochondrial fission and oxidative stress in hepatocytes. Our study illustrates that Slc25a47 is a key molecular for hUC-MSCs to improve liver fibrosis and regulates mitochondrial function through Sirt3 for the first time, and providing a theoretical basis for the clinical translation of hUC-MSCs transplantation in the treatment of patients with liver fibrosis/cirrhosis. • hUC-MSCs transplantation alleviate mice liver fibrosis and improve liver function. • mitochondrial NAD+ transporter Slc25a47 was decreased under stressful conditions. • hUC-MSCs reduced hepatic oxidative stress and mitochondrial damage. • hUC-MSCs improve mitochondrial dysfunction via increasing Slc25a47 expression and protein activity of Sirt3. [ABSTRACT FROM AUTHOR]

This work aimed to explore the underlying mechanism of plasma-activated water (PAW) promoting the heat-induced aggregation of myofibrillar protein (MP). The results of particle size and atomic force microscope indicated that PAW accelerated the aggregation of MP with PAW 60 showing the densest and most homogeneous crosslinking morphology. Raman spectroscopy showed that about 4.11% of the α-helix in PAW 60 changed to β-sheet during heating. The effects of PAW on the oxidation of MP were assessed in terms of sulfhydryl, disulfide bonds, carbonyl content and surface hydrophobicity. The amino acid composition revealed that the content of tyrosine dropped from 45.43 mg/g of PAW 0 to 37.35 mg/g of PAW 240 , indicated that tyrosine in MP was converted to dityrosine by PAW. These results indicate that PAW promotes the oxidation of MP and further changes in intra- and inter-molecular interactions, which provides a theoretical basis for PAW promoting thermal aggregation of MP. • PAW 60 showed the densest and most uniform network cross-linking structure at Stage 3. • PAW aided in the transition of secondary structure of MP from α-helix to β-sheet during heating. • PAW promoted time-dependently the oxidation of the sulfhydryl groups to disulfide bonds. • PAW promoted the aggregation of MP by modifying tyrosine to dityrosine. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Suanyu with mixed starter had higher total acidity, richer flavor and lower TVB-N. • Fermentation and thermal processing methods affected the flavor of Suanyu. • The roasted Suanyu showed a better flavor, color and sensory acceptability. • Mixed fermentation and roasting can be as a production method for precooked Suanyu. Suanyu is a famous traditional fermented aquatic food in south China. However, the quality of Suanyu is unstable due to natural fermentation based on the environment. This work screened suitable microbial fermenters (Enterococcus rivorum and Enterococcus lactis) from traditional fermented fish and optimized a suitable fermentation process. Effects of different fermentation (natural and mixed starters fermentation) and thermal treatments (microwave, frying and roasting) on the flavor of Suanyu were investigated. Compared to the natural fermentation group, the TVB-N content (31.5 mg/100 g) was lower, the total acidity (5.12 g/kg) and flavor compounds content were richer in the mixed starters fermentation group (P < 0.05). But there was no significant difference in histamine content (P > 0.05). The roasting treatment group contained higher contents of free amino acids, organic acids, nucleotides and richer key aroma components. The electronic nose was able to distinguish between the differently treated samples. The sensory evaluation result showed that roasted and fried samples had a more acceptable flavor and color. This work will provide a theoretical reference for the standardized production of Suanyu and the development of pre-cooked products. [ABSTRACT FROM AUTHOR]

• Arg combined with TGase improved the gel properties of low-salt surimi induced by MW. • A compact network of low-salt surimi gel was obtained if Arg was added before TGase. • Arg increased proportion of immobilized water and decreased proportion of free water. • Arg induced a shift of α-helix bands and increase in definition of β-sheet bands. • The binding sites between Arg and myosin were revealed via molecular docking technique. The reduction of the salt content of foods is of interest for health reasons. The present study showed that low-salt surimi gels could be produced using a combination of l -arginine (Arg) and transglutaminase (TGase) under microwave (MW) irradiation. The low-salt surimi gels produced by MW had similar physicochemical properties as regular-salt surimi gels produced by conventional two-stage water bath heating. Compared to low-salt surimi gels containing TGase alone, Arg increased the water holding capacity and gel strength (P < 0.05) and promoted the formation of a more homogeneous and compact three-dimensional gel network. As a result, there was a significant increase in the proportion of immobilized water and decrease in the proportion of free water (P < 0.05). The nature of the binding sites between Arg and myosin heavy chain was predicted using the molecular docking simulations analysis. These results may be useful for the development of low-salt surimi products. [ABSTRACT FROM AUTHOR]

• Arg and ultrasound played synergistic roles in enhancing stability of the emulsion. • Arg strengthened the effect of ultrasound in the adsorption of interfacial myosin. • Arg and ultrasound induced the exposure of aromatic and aliphatic amino acid. • Arg and ultrasound increased the ordered structures content of interfacial myosin. • Protein gelation network of emulsion droplet formed under Arg and ultrasound. The effects of l -arginine (Arg)-assisted ultrasonic treatment on the molecular and interfacial characteristics of myosin and emulsifying properties of the emulsion were evaluated to ascertain the underlying mechanism in improving the emulsion stability. Ultrasonication induced the exposure of residues of native myosin, which was increased by the addition of Arg (40 mM). Furthermore, in terms of emulsions containing Arg, the higher the ultrasonication intensity was, the greater the increase in adsorbed protein (from 15.43 ± 0.28% to 50.49 ± 1.65%) and π value, and the decrease in droplet sizes (from 4098 nm to 2324 nm) (P < 0.05). Moreover, the increase in the ordered structures of interfacial myosin induced by Arg and ultrasonication favoured the formation of a protein gelation network. In summary, Arg-assisted ultrasonic treatment improved the stability of the emulsion by inducing the exposure of native myosin and facilitating the formation of ordered structures of interfacial myosin. [ABSTRACT FROM AUTHOR]

• 124 components in fermented barley aqueous extract were identified by UPLC-HRMS. • PCA distinguished the samples and visualized the process with fermentation time. • Metabolomics revealed the change of components in barley with fermentation time. • Phytochemicals and metabolites were released and accumulated by L. plantarum dy-1. • Indole-3-lactic acid, etc. were identified as significant increasing components. Fermentation has been considered as effective tools to promote the functional properties of cereals. In this paper, barley flour was fermented with Lactobacillus plantarum dy-1 (L. plantarum dy-1) and the main components in the fermented barley aqueous extracts were identified using by ultra-high performance liquid chromatography tandem with high resolution mass spectrometry (UPLC-HRMS), and investigated by metabolomics strategy involved on chemometrics. The barley extracts were prepared at the fermentation time of 0, 4, 8, 12, 16, 20, 24, 28 h, respectively and a total of 124 compounds were detected in the samples. Principal component analysis (PCA) was performed and the results indicated that the fermentation process became to slow down from 16 h until terminated. During fermentation, saccharides, amino acids, nucleosides, and some organic acids decreased, while lipids and bioactive molecules in barley were released and metabolites were accumulated by L. plantarum dy-1. Meanwhile, partial least squares discrimination analysis (PLS-DA) was performed for revealing the characteristic components in fermented barley aqueous extracts, including some functional molecules such as indole-3-lactic acid, phenyllactic acid, homovanillic acid and cafestol, etc., which provided the roles of them and the basis for further investigation on the functional bioactivities and application. [ABSTRACT FROM AUTHOR]