Total Sulfhydryl Research Articles

Transformation of high moisture extrusion on pea protein isolate in melting zone during: From the aspects of the rheological property, physicochemical attributes and modification mechanism

Plant-based meat analogs are emerging products mainly produced by extruder. To reveal the “black box” processing mechanism of extrusion, the physicochemical and rheological properties of pea protein isolate (PPI) were evaluated at different extrusion temperatures (90 °C, 100 °C, 110 °C, 120 °C and 130 °C) and moisture contents (65% and 70%) by using rheological simulation and stop-operation. The results showed a gel-like PPI paste, which presented shear thinning gel-like behavior and strong elastic characteristics. The weaken strain overshoot behavior of the PPI paste transformed to a strong strain overshoot with temperature increased under large amplitude oscillation. The PPI molecules transformed from a spherical structure to a tangled fibrous network, the absolute zeta potential value increased, and the total SH decreased. The native-like secondary structures of PPI were lost, and the relatively rigid protein structure was broken with increasing temperature. The tertiary structure of the raw material is gradually lost, and the Trp residue is transferred from the spherical structure interior to the surface of the protein molecule. The protein subunits were not decomposed during the extrusion process, and although the thermal stability of the PPI was reduced, new cross-links of higher bond energy could be formed at higher temperatures. Moreover, a higher extrusion temperature and proper moisture content can result in partial unfolding and realignment of extruded PPI.

Oleic Acid Facilitates Cd Excretion by Increasing the Abundance of Burkholderia in Cd-Exposed Mice

As a global pollutant, cadmium (Cd) can easily enter the body through food chains, threatening human health. Most Cd is initially absorbed in the gut, with the gut microbiota playing a pivotal role in reducing Cd absorption and accumulation. This study assessed the effects of three fatty acids on Cd accumulation and toxicity in Cd-exposed mice. The results showed that oleic acid (OA) was the most effective in facilitating Cd excretion in mice among these fatty acids. The use of OA led to reduced Cd accumulation in the organs and increased Cd content in the feces. The metagenomic analysis of the gut microbiota showed that the genus Burkholderia was the most significantly restored by OA in Cd-exposed mice. Burkholderia cepacia, as the type species for the genus Burkholderia, also exhibited strong Cd tolerance after treatment with OA. Furthermore, the electron microscopy analysis showed that most of the Cd was adsorbed on the surface of B. cepacia, where the extracellular polymeric substances (EPSs) secreted by B. cepacia play a key role, displaying a strong capacity for Cd adsorption. The peak at 2355 cm-1 and the total sulfhydryl group content of EPSs showed significant increases following co-treatment with Cd and OA. The results demonstrated the potential roles that gut Burkholderia may play in OA-mediated Cd excretion in mice.

A comparative study of vacuum tumbling and immersion marination on quality, microstructure, and protein changes of Xueshan chicken.

Marination is a common technology in meat processing with advantages of enhancing tenderness, water retention, and overall quality. This study was conducted to investigate the effect of vacuum tumbling and immersion marination on meat quality, microstructure, water mobility, protein changes, and denaturation of Xueshan chicken. Results showed that vacuum tumbling significantly increased the marinating rate of chicken, tenderness, meat texture, and water retention. Meanwhile, vacuum tumbling decreased total sulfhydryl content alongside an increased protein surface hydrophobicity and free sulfhydryl content, indicating that vacuum tumbling elevated the degree of protein denaturation. Further, the peak area corresponding to the relaxation time T22 after vacuum tumbling was significantly higher than that of immersion marination, suggesting that the stability of the immobilized water of chicken was reduced by vacuum tumbling. Compared to immersion marination, vacuum tumbling improved myofibril fragmentation index (MFI) presenting fewer myofibrillar protein bands in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel and more damaged muscular cells. Overall, vacuum tumbling could improve the marination absorptivity, protein degradation, and denaturation, resulting in changes in myofibril structure and meat quality of Xueshan chicken.

Development of Flavor and Taste Components of Sous-Vide-Cooked Nile Tilapia (Oreochromis niloticus) Fillet as Affected by Various Conditions.

This study aims to shed light on the association between non-volatile and volatile compounds related to flavor/taste characteristics as well as sensory acceptability of Nile tilapia fillet (Oreochromis niloticus) cooked by various sous-vide (SV) conditions (50-60 ℃, 30-60 min), with fish cooked with boiling water used as control. Higher temperatures and longer processing times of SV cooking led to greater protein and lipid oxidation as indicated by the increase in total sulfhydryl (-SH), carbonyl, free fatty acid (FFA) contents as well as peroxide values (PV) and thiobarbituric acid reactive substance (TBARS) values. The differences in flavor/taste components including adenosine triphosphate (ATP)-related compounds, free amino acids (FAAs) and volatiles were also obtained, which directly affect sensory acceptability as evaluated by using the hedonic scale. Based on principal component analysis (PCA) results, the acceptability score was strongly correlated with inosine monophosphate (IMP) and acetoin, which seem to be the most crucial flavor enhancers for cooked tilapia. Among all samples, tilapia processed at 60 °C for 45 and 60 min, which contained significantly higher IMP and acetoin (p < 0.05) than others, had significantly higher flavor-liking and overall-liking scores, with a more than 7.5 meaning for high acceptability (p < 0.05), indicating the optimal SV conditions for tilapia fillet. Overall, the present finding indicated that the SV-cooking technique, at the optimal conditions, can improve the meat quality of cooked fish, in terms of flavor/taste characteristics, compared with traditional cooking (control).

Origin of static magnetic field induced quality improvement in sea bass (Lateolabrax japonicus) during cold storage: Microbial growth inhibition and protein structure stabilization.

To explore the potential application of static magnetic field (SMF) treatment in marine fish preservation, the sea bass (Lateolabrax japonicus) was exposed to SMF (5 mT) and its quality changes during cold storage were evaluated by total viable counts, water holding capacity, pH, color, and textural properties. Characteristics of the protein in the presence of SMF were investigated by measuring total sulfhydryl (SH) content, Ca2+-ATPase activity, secondary structure, and muscle microstructure. SMF treatment exhibited positive effects on fish quality, showing favorable performance on the most quality indicators, especially a significant reduction in the Microbial Counts. Furthermore, higher total SH content and Ca2+-ATPase activity were observed in SMF-treated samples, demonstrating that the oxidation and denaturation of myofibrillar protein (MP) were delayed due to SMF treatment. The transformation of α-helix to random coil was prevented in SMF-treated samples, indicating that the secondary structure of MP was stabilized by SMF treatment. The above changes in protein structures were accompanied by changes in muscle microstructure. More intact and compact structures were observed in SMF-treated samples, characterized by well-defined boundaries between myofibers. Therefore, our findings suggest that under the conditions of this article, SMF treatment could maintain the quality of fish mainly by inhibiting the growth of microorganisms and enhancing the stability of protein structures, and could be a promising auxiliary technology for preservation of aquatic products.

Hyperglycemia enhances the generation of ROS and RNS that impair antioxidant power and cause oxidative damage in human erythrocytes.

Hyperglycemia is a state in which excess glucose circulates in blood. Erythrocytes are in direct contact with this high glucose concentration and are greatly affected by it. We have examined the effect of hyperglycemic condition on isolated human erythrocytes under in vitro conditions. Erythrocytes were incubated with different concentrations of glucose (5, 15, 30, 45 mmol/L) for 24 h, and several biochemical parameters were determined. Treatment with high glucose concentrations increased heme degradation and methemoglobin level, while methemoglobin reductase activity was decreased. A significant increase in protein oxidation and lipid hydroperoxides with a decrease in total sulfhydryl content was seen. This suggested the generation of oxidative stress, which was confirmed by an enhanced production of reactive oxygen and nitrogen species. Hyperglycemia led to a significant decline in the antioxidant power of erythrocytes, lowering their ability to quench free radicals and reduce metal ions to lower oxidation states. The plasma membrane redox system was upregulated, while ascorbate free radical reductase activity was lowered. Glucose exposure inhibited the enzymes of glycolysis and hexose monophosphate shunt. Electron microscopy showed morphological changes resulting in the formation of echinocytes. Thus, the hyperglycemic condition generates reactive species that oxidize proteins, hemoglobin, and lipids; impair the total antioxidant capacity; and alter morphology in human erythrocytes.

Influence of rose anthocyanin extracts on physicochemical properties and in vitro digestibility of whey protein isolate sol/gel: Based on different pHs and protein concentrations

Protein-polyphenol interactions can improve the physicochemical properties of proteins. The objective of this study was to investigate the influence of rose anthocyanin extracts (RAEs) on the physicochemical properties and digestibility of whey protein isolate (WPI) sol/gel at different pHs and protein concentrations. Hydrophobicity interaction and ionic bonding were the main forces for the formation of acidic WPI and WPI-RAEs sol/gel. When pH was higher than 2.4, sol/gel became unstable, which may be related to hydrophobicity, ζ-potential value, total sulfhydryl and free sulfhydryl content changes. In addition, RAEs had positive effects on the color and water distribution of all WPI sol/gel. Moreover, RAEs improved the viscoelasticity of WPI sol/gel with protein content ≥ 12 % (w/v) at pH 2.4. More importantly, the addition of RAEs could reduce the digestibility of WPI sol/gel. We hope our works can provide promising strategies for developing WPI-RAEs foods.

Interactions of heat-induced myosin with hsian-tsao polysaccharide to affect the fishy odor adsorption capacity

The interaction mechanism of hsian-tsao polysaccharide (HTP) with unique gel-promoting and biological activity for improving the gel properties of surimi was not clarified. This study investigated the effects of HTP on heat-induced structural changes and the adsorption capacity of myosin to fishy odor compounds (hexanal, heptanal, nonanal, and 1-octen-3-ol). HTP concentration and heating ways greatly affected the physicochemical properties of myosin. Adding hydrophilic HTP covering the myosin surface aided in unfolding the structure of myosin and further disturbed the myosin aggregation with surface hydrophobicity decreased and total sulfhydryl contents increased. The main physical forces arising from hydrogen bonding and electrostatic interactions contributed to forming HTP-myosin complexes under setting (40 °C, 30 min), whereas cross-links occurred by enhanced hydrophobic interactions forming insoluble HTP-myosin complexes under two-step heating (40 °C, 30 min; 90 °C, 20 min), indicative of decreased solubility and increased turbidity, as evidenced by zeta potential, FTIR, fluorescence and UV–vis spectra, and fluorescence microstructure. This resulted in the transformation of secondary structure of myosin from α-helix to β-sheet with the increase of HTP. Furthermore, HTP interacting with myosin reduced the fishy odor binding capacity of myosin thus promoting the release during processing, as demonstrated by HS-SPME-GC. The findings provided new insight into the mechanism of regulating the fishy odor binding ability of myosin by application of HTP.

Vochysia rufa and glibenclamide promote effects on oxidative damage and in proteins implicated in vesicular trafficking in diabetic rat brain

Many Vochysiaceae species are widely used in folk medicine to treat some diseases. Vochysia rufa, popularly known as “quina-doce”, has been used in folk medicine to treat type 1 and type 2 diabetes mellitus in the state of Minas Gerais, Brazil. Although the antidiabetic and antioxidant effects and phytochemical profile of Vochysia rufa have already been elucidated, further studies are needed on the effects of this treatment in specific tissues, such as the brain. This study investigated the effect of aqueous extract of Vochysia rufa in diabetic rat brains and for this purpose, oxidative stress markers and the expression/localization of proteins implicated in vesicular trafficking were evaluated. Thirty-two rats were randomized into four groups (non-diabetic, diabetic non-treated, diabetic treated for 43 days with glibenclamide - 6 mg/kg or Vochysia rufa - 500 mg/kg). The extract was administered by gavage for 43 days. Analyses were conducted of enzymes concentration and activity in the brain. The protein levels and localization of myosin-Va, CaMKII, synapsin, SNAP-25 and GLUT4 were also analyzed. Vochysia rufa extract decreased superoxide dismutase, glutathione peroxidase, reduced glutathione, total sulfhydryl and lipid peroxidation levels and increased glutathione S-transferase levels. Additionally, Vochysia rufa treatment increased the expression of myosin-Va, CaMKII and also synapsin, which were confirmed by immunolocalization. The treatment with aqueous extract of Vochysia rufa reduces oxidative stress on diabetic rat and protecting the brain from damage caused by hyperglycemia.

High-intensity ultrasound improved the physicochemical and gelling properties of Litopenaeus vannamei myofibrillar protein

The effects of high-intensity ultrasound on the physicochemical and gelling properties of Litopenaeus vannamei (L. vannamei) myofibrillar protein (MP) were investigated. MP solutions were subjected to ultrasound treatment (power 100 W, 300 W, and 500 W). It was found that the carbonyl and free amino contents of MP increased significantly with increasing ultrasound power, accompanied by enhanced emulsification properties. The increase of free radical and carbonyl content indicated that ultrasound induced the oxidation of MP. With the increase of ultrasound power, it was found that the total sulfhydryl content of the shrimp MP decreased, but the surface hydrophobicity increased significantly, which might be closely related to the conformational changes of MP. Meanwhile, a significant increase of β-sheet but a decrease of α-helix in the secondary structure of MP was observed with increasing ultrasound power, indicating that ultrasound treatment induced the stretching and flexibility of MP molecules. SDS-PAGE showed that L. vannamei MP consisted of myosin heavy chain, actin, myosin light chain, paramyosin and tropomyosin. Ultrasound treatment could lead to some degree of oxidative aggregation of MP. The results of rheological properties indicated that ultrasound treatment enhanced the viscoelasticity of MP and further improved the gel strength of MP gel. This study can provide a theoretical basis for the functional modification of shrimp MP and the processing of its surimi products.

Effects of ultrasonic–microwave combination treatment on the physicochemical, structure and gel properties of myofibrillar protein in Penaeus vannamei (Litopenaeus vannamei) surimi

The objective of this study was to evaluate the effects of single ultrasound (360 W, 20 min), single microwave (10 W/g, 120 s) and ultrasonic–microwave combination treatment on shrimp surimi gel properties. The structure and physicochemical properties of myofibrillar protein (MP) were also determined. Low-field nuclear magnetic resonance showed that the fluidity of water molecules and the moisture content decreased, the stability and water holding capacity (WHC) increased after single ultrasound, single microwave and ultrasonic–microwave combination treatment. Compared with the traditional water bath treatment, ultrasound and microwave treatment reduced the total sulfhydryl content and promoted the formation of intermolecular disulfide bonds and hydrophobic interactions, which improved the compactness of the network structure of shrimp surimi gel. Moreover, Fourier transform infrared spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis revealed that these treatments not only inhibited the degradation of MP, but also decreased the α-helix content and increased the β-sheet content. The three treatments also significantly reduced the particle size and decreased the solubility of MP. Overall, the effect of ultrasonic–microwave combination treatment was superior to that of either single treatment.

Cadmium chloride generates cytotoxic reactive species that cause oxidative damage and morphological changes in human erythrocytes.

Cadmium chloride (CdCl2) is a widely used industrial compound that exhibits multiple organ toxicity. Cadmium is transported through blood where erythrocytes are exposed to its action. Here the effect of CdCl2 on human erythrocytes was examined under in vitro conditions. Human erythrocytes were treated with 0.01-0.5mM CdCl2 for 24h at 37 °C. Lysates were made from CdCl2 treated and untreated (control) cells and used for further analysis. CdCl2 treatment resulted in marked hemolysis of erythrocytes and oxidation of hemoglobin to methemoglobin. This will result in anemia and also reduce the oxygen carrying ability of erythrocytes. Hemoglobin oxidation was accompanied by degradation of heme and release of free ferrous iron moiety. Further analysis showed elevated lipid hydroperoxides and formation of advanced oxidation protein products along with reduction in total sulfhydryl content, indicating the generation of oxidative stress condition in the cell. Incubation of erythrocytes with CdCl2 enhanced generation of reactive oxygen and nitrogen species, decreased the antioxidant power and inhibited pathways of glucose metabolism. Plasma membrane was damaged as indicated by enhanced osmotic fragility and inhibition of membrane bound enzymes. This was confirmed by electron microscopy which showed formation of echinocytes. These results show that CdCl2 generates reactive species which impair the antioxidant system resulting in oxidative damage to erythrocytes.

Improvement in Emulsifying Capacity of Goose Liver Protein Treated by pH Shifting with Addition of Sodium Tripolyphosphate and Its Proteomics Analysis.

Goose liver isolate treated by pH shifting and pH shifting/non-enzyme phosphorylation with goose liver isolate was used as a control. The functional property differences in the protein and proteins involved in the interfacial layer treated with pH shifting and non-enzyme phosphorylation were studied. Compared with the goose protein isolates (GPIs) at pH 7.0, the GPIs treated by pH shifting was not a good choice to be an emulsifier in a neutral environment, and non-enzyme phosphorylation inhibited the negative effects of pH shifting treatment and improved protein properties. The results of proteomics showed that the identified proteins in the interfacial layer belong to hydrophilic proteins. Non-enzyme phosphorylation increased the abundances of most proteins due to ion strength, including some phosphorylated proteins. Correlation analysis indicated that protein solubility was highly positively related with S0, intrinsic fluorescence, total sulfhydryl, free sulfhydryl, A0A0K1R5T3, R0KA48, R0KFP7, U3J1L1, P01989, R0JSM9, and R0LAD1, and was also highly negatively related with particle size and R0M210, R0M714, and R0LFA3. The emulsifying activity index (EAI) demonstrated highly positive correlation with protein solubility, and was correlated with R0JKI4, R0KK84, R0L1Y3, R0LCM7, A0A068C605, and U3IW62.

Structural transformation of egg white protein particles modified by preheating combined with pH-shifting: Mechanism of enhancing heat stability

This study aimed to modify egg white protein particles (EPs) through pH-shifting combined with preheating. EPs were subjected to pH treatment (3, 7, 8, and 10) for 1 h with preheating (75 °C for 30 min) and then adjusted to neutral. The thermal stability of the EPs was measured by heating them at 90 °C for 15 min. Particle size distribution revealed that the EPs modified by preheating at pH 10 (EPs10) performed the smallest particle size among all samples, which decreased the aggregation extent of the particles under heat stress. The total sulfhydryl contents of EPs10 did not significantly decrease under heat stress, indicating that intramolecular disulfide bonds were formed and prevented covalent interactions between particles. Solubility and turbidity measurements indicated that EPs10 retained the best physicochemical properties under heat stress among all samples. In terms of emulsification, EPs10 had a higher elastic interfacial protein layer than EPs3 and native egg white protein because of the exposure of hydrophobic and surface free –SH groups. The emulsions of EPs10 showed the best thermal stability among all samples. This research provided a theological basis for heat-stable egg white protein particles and a practical method for the industry to process EWP-based emulsifiers.

Effects of iron-catalyzed oxidation and methemoglobin oxidation systems on endogenous enzyme activity and myofibrillar protein degradation in yak meat

In this study, the effects of different oxidation intensities on the degradation of myofibrillar protein by endogenous enzymes in iron-catalyzed oxidizing (IOS) and metmyoglobin oxidizing system (MOS) were compared. The results showed that carbonyl content and endogenous enzyme activities (caspase-3, caspase-6 and calpain-1) increased significantly and the total sulfhydryl content decreased significantly with H2O2 concentration in both oxidation systems. Meanwhile, the rate of carbonyl formation and the inhibition of endogenous enzymes activities of IOS were significantly lower than MOS for the same oxidation intensity. In addition, IOS and MOS mainly produced myosin light chains degradation products of 20–25 kDa and 20–17 kDa. At the same oxidation intensity, MOS of myofibrillar protein significantly enhanced the degradation of troponin-T and desmin by caspase-3/-6 compared with IOS, while inhibiting the degradation of troponin-T by calpain-1. In conclusion, MOS inhibited endogenous enzyme degradation in vitro more than IOS during post-slaughter maturation of yak meat.

Soy protein–phlorizin conjugate prepared by tyrosinase catalysis: Identification of covalent binding sites and alterations in protein structure and functionality

Tyrosinase-catalyzed synthesis of soy 7S/11S–phlorizin conjugates was performed, and the reaction sites, conformation alterations and functional properties of complexes were evaluated using proteomic, in combination with multispectral technologies. Phlorizin was conjugated to 7S/11S primarily via residues of Lys, Cys, His and Arg residues. The phlorizin binding equivalents and decreased contents of free and total sulfhydryl groups and free amino groups confirmed the covalent interaction in the 7S/11S–phlorizin complexes. Conjugation with phlorizin promoted the conversion of α-helix to β-sheet and β-turn, with simultaneous transformation of the microenvironments around Trp and Tyr residues to hydrophilic and hydrophobic microenvironments, respectively, and lowering of the surface hydrophobicity of 7S/11S. The DPPH and ABTS radical scavenging abilities and α-glucosidase inhibitory activities of 7S/11S were increased by three–, two– and three–fold after the covalent binding of phlorizin. The study provided an ideal tyrosinase-catalyzed approach to fabricate custom–tailored nutritional soy protein–polyphenol products.

Bioreduction mechanisms of high-concentration hexavalent chromium using sulfur salts by photosynthetic bacteria

Eliminating “sulfur starvation” caused by competition for sulfate transporters between chromate and sulfate is crucial to enhance the content of sulfur-containing compounds and improve the tolerance and reduction capability of Cr(VI) in bacteria. In this study, the effects of sulfur salts on the Cr(VI) bioremediation and the possible mechanism were investigated in Rhodobacter sphaeroides SC01 by cell imaging, spectroscopy, and biochemical measurements. The results showed that, when the concentration of metabisulfite was 2.0 g L−1, and the initial OD600 was 0.33, the reduction rate of R. sphaeroides SC01 reached up to 91.3% for 500 mg L−1 Cr(VI) exposure at 96 h. Moreover, thiosulfate and sulfite also markedly increased the concentration of reduced Cr(VI) in R. sphaeroides SC01. Furthermore, the characterization results revealed that –OH, –CONH, –COOH, –SO3, -PO3, and -S-S- played a major role in the adsorption of Cr, and Cr(III) reduced by bacteria was bioprecipitated in the production of Cr2P3S9 and CrPS4. In addition, R. sphaeroids SC01 combined with metabisulfite significantly increased the activity of glutathione peroxidase and the content of glutathione (GSH) and total sulfhydryl while decreasing reactive oxygen species (ROS) accumulation and cell death induced by Cr(VI) toxic. Overall, the results of this research revealed a highly efficient and reliable strategy for Cr(VI) removal by photosynthetic bacteria combined with sulfur salts in high-concentration Cr(VI)-contaminated wastewater.

Phosphorylated Trehalose Suppresses the Denaturation of Myofibrillar Proteins in Peeled Shrimp (Litopenaeus vannamei) during Long-Term Frozen Storage

The protective effects of phosphorylated trehalose on the quality and characteristics of peeled shrimp (Litopenaeus vannamei) were determined. Quality changes in treated samples were evaluated by assessing the physicochemical properties of myofibrillar proteins (MP) and compared to fresh water-, sodium tripolyphosphate-, and trehalose-treated samples during 12 weeks of frozen storage. The sensitivity of MP to oxidation and denaturation was increased during frozen storage. Phosphorylated trehalose significantly improved the quality of shrimp by increasing water-holding capacity. Further analysis showed that the addition of phosphorylated trehalose reduced the decrease in soluble MP content, Ca2+-ATPase activity, and total sulfhydryl contents and also effectively inhibited the increase in the surface hydrophobicity of MP. In addition, atomic force microscopy and hematoxylin and eosin staining revealed that phosphorylated trehalose preserved the integrity of the myofibril microstructure. Thermal stability results further confirmed that the denaturation temperature and denaturation enthalpy of MP were improved by phosphorylated trehalose. Overall, phosphorylated trehalose suppresses the denaturation of MP in peeled shrimp during long-term frozen storage.

Modification of functional properties of mussel actomyosin by ultrasound treatment and the appplication at O/W emulsion

Effects of ultrasonication (0 W, 150W, 300 W, 450 W, 600 W) for 16 min on the functional properties of mussels actomyosin (MAP) and the application at oil-in-water emulsion were investigated. Ultrasonication modified the physicochemical properties of MAP, consequently improving the emulsifying properties of MAP. Particle size and total sulfhydryl group content of ultrasonicated MAP decreased. However, free sulfhydryl content, absolute zeta-potential (from 17.18 to 41.00) and surface hydrophobicity increased. Ultrasonication improved solubility (from 38.5% to 57.1%) and emulsifying properties of MAP. In addition, the interfacial tension of MAP after ultrasonic treatment was reduced, which improved its adsorption rate at the oil-water interface (from 14.5% to 32.8%). Rheological properties of emulsion were improved after ultrasonication at 300 W. However, when the ultrasonic power increased from 300 W to 600 W, the emulsifying properties of MAP of the emulsion decreased. This may be due to excessive ultrasound treatment leading to protein aggregation and larger particle size, thereby reducing the protein adsorption rate at the oil-water interface. The results of this research suggested that ultrasound treatment has great potential in modifying emulsifying properties of shellfish muscle proteins, and ultrasound treatment at 20 kHz, 300W for 16 min was the optimum condition for modification.

Seaweed Slurry Improved Gel Properties and Enhanced Protein Structure of Silver Carp (Hypophthalmichthys molitrix) Surimi.

In order to improve the gel quality of silver carp (Hypophthalmichthys molitrix) surimi, the texture and rheological properties and microstructure of silver carp surimi gel products were analyzed by adding Laminaria japonica (LJ), Undaria pinnatifida (UP) and Sargassum fusiforme (SF) slurries. After adding kelp slurry (KS), the gel strength reached the highest level of 1047.26 ± 85.04 (g·mm). The carbonyl content and surface hydrophobicity of surimi protein increased, while the free amino groups, total sulfhydryl groups, and fluorescence intensity decreased significantly. The results of transform infrared spectroscopy (FT-IR), circular dichroic (CD), and Raman spectra showed that the KS promoted the change of the secondary structure of protein. Scanning electron microscopy (SEM) images revealed that kelp slurry had a more compact gel microstructure. In conclusion, the kelp slurry could significantly increase the gel strength, improve the quality of surimi products, enrich the nutrition of silver carp surimi, and have great significance for expanding the application range of seaweed.