Myofibrillar Protein Structure and Gel Properties of Trichiurus Haumela Surimi Subjected to High Pressure or High Pressure Synergistic Heat

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

BACKGROUND

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

RESULTS

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

CONCLUSION

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

Understanding the Role of Filamentous Actin in Food Quality: From Structure to Application

Actin, a multifunctional protein highly expressed in eukaryotes, is widely distributed throughout cells and serves as a crucial component of the cytoskeleton. Its presence is integral to maintaining cell morphology and participating in various biological processes. As an irreplaceable component of myofibrillar proteins, actin, including G-actin and F-actin, is highly related to food quality. Up to now, purification of actin at a moderate level remains to be overcome. In this paper, we have reviewed the structures and functions of actin, the methods to obtain actin, and the relationships between actin and food texture, color, and flavor. Moreover, actin finds applications in diverse fields such as food safety, bioengineering, and nanomaterials. Developing an actin preparation method at the industrial level will help promote its further applications in food science, nutrition, and safety.

Structural properties and emulsification of myofibrillar proteins from hairtail (Trichiurus haumela) at different salt ions

The structural properties and emulsification of myofibrillar proteins (MPs) are susceptibly affected by salt ions. The effect of different salt ions on the structural properties and emulsification of MPs from hairtail (Trichiurus haumela) remains unclear. Hairtail MPs were analyzed under different ion treatments of Na+, K+, Ca2+ and Mg2+. MPs at K+ and Na+ treatment showed a similar trend on salt effect due to the unfolding of proteins under salt ions. However, the excessive electrostatic effect of divalent ions could enhance protein aggregation, especially at Ca2+ and Mg2+. The β-sheet of MPs at different salt ions interconverted with α-helix and random coil at ionic strengths from 0.1 mol/L to 1.0 mol/L. The surface hydrophobicity and active sulfhydryl content of MPs increased with the improvement of ionic strengths at 0-0.8 mol/L. Under Ca2+ and Mg2+ treatments, the turbidity of MPs was low compared to that under the treatment of Na+ and K+. Additionally, the emulsification of hairtail MPs treated with different ions was improved at an ionic strength of 0.6 mol/L. This study can contribute to using salts in constructing fish protein-based emulsions for manufacturing emulsified surimi products and promoting the development and utilization of hairtail proteins.

Impact of L-arginine on the quality of heat-treated Antarctic krill: Influence of pH and the guanidinium group

Antarctic krill suffers from severe water loss after heating, and its quality deteriorates, so it is in urgent need of a green and healthy improver. In this paper, the effects of L-arginine (L-Arg) soaking on the modification of the quality of heat-treated Antarctic krill and the structure of myofibrillar proteins (MPs) in Antarctic krill were investigated. The results showed that L-Arg had an ameliorating effect on heat-treated krill in a concentration-dependent relationship. The water-holding capacity of L-Arg-soaked krill was 1.41 times higher than that of sodium tripolyphosphate (STPP) at an equivalent concentration (80 mM). At 120 mM L-Arg soaked, L* and hardness of krill decreased to 58.31 and 334.81 g, while resilience and moisture content increased to 0.47 and 85.29 % after heating, respectively. The scanning electron microscopy (SEM) results revealed that the tissue state of the pH-corrected groups was better than the control, but not as well as that of the pH-uncorrected groups. pH and the guanidinium group in L-Arg both played roles in promoting the transition of MPs from disordered to ordered secondary structures. This transition reduced the exposure of hydrophobic and sulfhydryl groups in MPs, inhibited the protein aggregation and increased the solubility of MPs to 71.61 %, which ultimately improved the quality of heat-treated krill. It is worth noting that the pH effect had a primary influence on the observed effects, while the guanidinium group made a secondary contribution. These results could broaden the potential application of L-Arg as an improver of the quality of heat-treated krill.

Enhanced fresh-keeping capacity of printed surimi by Ca2+-nano starch-lutein and its nondestructive freshness monitoring based on 4D printed anthocyanin

To solve undiscernible freshness changes of printed functional surimi while maintaining printed shape, 4D printable color-changing material were prepared. Firstly, based on results of printing properties and fresh-keeping of Ca2+-NS-L-surimi, it showed better printing effects (enhanced mechanical strength) and good preservation (inhibition of amino acids decomposition, bacterial growth). However, freshness changes of printed Ca2+-NS-L-surimi were not distinguished directly. To avoid that, 4D printable color-changing material-anthocyanin-hydroxypropyl methyl cellulose-xanthan gum-carrageenan (AHXK) was prepared for indicating freshness through discoloration. Printing results showed AHX with 5 % K had the most suitable mechanical strength (appropriate gel strength, texture, rheology) for printing. Based on that, AHXK had stable color (ΔE fluctuation <5) and was sensitive to pH and ammonia (obvious discoloration; ΔE > 10). Actual freshness monitoring results (co-printing of AHXK-surimi) exhibited significant discolorations, especially for HXK with 0.75 % A. It became green during refrigeration of 3-5 d (keeping fresh, ΔE < 4), brighter green at 7 d (decreased freshness, ΔE > 6), turned yellow at 9 d (spoilage, ΔE > 16), which were distinguished significantly with naked eyes rather than traditional freshness determining. In conclusion, printed AHXK-functional surimi exhibited good printing, preservation and nondestructive freshness monitoring, facilitating application of 3D printed functional surimi.

Effect of cellulose on gel properties of heat-induced low-salt surimi gels: Physicochemical characteristics, water distribution and microstructure

The processing of surimi products requires the addition of high levels of salt, which makes it a high-salt food that poses a risk to human health. The search for exogenous additives to reduce the salt content of surimi products while ensuring their quality characteristics is crucial. Therefore, the effect of different species of cellulose on enhancing the quality characteristics of low-salt surimi gels was investigated and the best-modified cellulose was identified. Carboxymethyl cellulose (CMC), hydroxypropyl methylcellulose (HPMC), and microcrystalline cellulose (MCC) were selected for this study to compare with high-salt control and low-salt control. The results showed that cellulose could induce conformational transitions of proteins and promote the formation of an ordered and dense surimi gel network and the minimum porosity of 15.935% was obtained in the MCC-treated group. The cellulose-treated group conferred good textural properties to the surimi gels, significantly improved gel strength and water retention capacity (p < 0.05), and reduced the amount of water lost after cooking treatment (p < 0.05). Low-field NMR results showed that cellulose reduced the release of water, converting more free water to immobile water, thus increasing the water proton density. The higher energy storage modulus G' in the presence of cellulose indicated a more stable surimi gel system dominated by springiness. In summary, cellulose could confer better quality characteristics to low-salt surimi gels and MCC performance was superior to other cellulose species. This study helps the understanding of the mechanism of cellulose-surimi action on the development of high-quality low-salt surimi gels.

Lacticaseibacillus paracasei fermentation broth identified peptide, Y2Fr, and its antibacterial activity on Vibrio parahaemolyticus

Although Vibrio parahaemolyticus infections cause severe diseases of large yellow croaker (Larimichthys crocea), using antibiotics and other chemical agents to treat these infections could result in antimicrobial resistance, environmental pollution, and other associated problems. This study identified seven peptides from Lacticaseibacillus paracasei fermentation broth using ultra-high-performance liquid chromatography-mass spectrometry and screened antimicrobial peptide Y2Fr (VEIKNGLLKLNGKPLLIR) through its net charge, hydrophobicity and predicted secondary structure. Antibacterial activity analysis revealed that Y2Fr had a minimum inhibitory concentration (MIC) of 125 μg/mL, minimum bactericidal concentration (MBC) of 250 μg/mL against V. parahaemolyticus and a time-kill of 3 h. In a bacterial membrane environment, the secondary structure of peptide Y2Fr changed from a random coil to a β-sheet to enhance its membrane permeability and binding to bacteria DNA to exert its antibacterial effect. Further molecular docking analysis revealed that peptide Y2Fr could bind to the membrane protein KKI11460.1 and DNA polymerase A0A0L8TVA4 of V. parahaemolyticus through hydrogen bonds. Meanwhile, treatment of Y2Fr with mammalian red blood cells and plasma revealed that it was noncytotoxic, nonhemolytic, and stable under physiological conditions. Thus, peptide Y2Fr has great potential use in treating and preventing infections caused by V. parahaemolyticus or similar bacteria in aquatic animals.

Effects of Freeze-Thaw Cycles on the Structures and Functional Properties of Clitocybe squamulosa Protein Isolates

Changes in the functional properties and structures of Clitocybe squamulosa protein isolate (CSPI) in the process of freeze-thaw (F-T) cycles were explored. Remarkable alterations and the reduced content of protein ordered structure were revealed through structural analysis of CSPI after F-T treatments. The surface hydrophobicity and free sulfhydryl content of CSPI first increased and then decreased. However, after the F-T treatments, the carbonyl content of CSPI continued to increase. Similarly, the water holding capacity (WHC), oil holding capacity (OHC), and solubility of CSPI all declined as the number of F-T cycles increased. The foaming properties and emulsifying properties of CSPI were significantly improved and reached maximum values after three F-T cycles. CSPI undergoing two F-T cycles showed the highest digestibility, maximum polypeptide content, and highest DPPH and ·OH-radical-scavenging activities. The ·OH-radical-scavenging activities and reducing power of the gastrointestinally digested CSPI had the highest value after one F-T cycle. Therefore, it has been demonstrated that F-T treatments could be a residue-free and cost-effective tool for improving mushroom protein functional properties.

Effect of high-pressure homogenization on Ca2+ -induced gel formation of soybean 11 S globulin

BACKGROUND

High-pressure homogenization (HPH) is commonly used as a non-thermal processing technique for soybean and soy protein products, and the preparation of soy protein gel products often requires the synergistic effect of HPH and heat treatment. The dissociative association behavior of 11 S is the key to the protein gel formation state. In this study, therefore, 11 S thermal gels were prepared by high-pressure homogenization and co-induction (90 °C, 30 min) (adding Ca²⁺ to promote gel formation before heat treatment), and the effects of different high-pressure homogenization pressures (0-100 MPa) and co-treatment on the dissociative association behavior of 11 S protein, gel properties, and microstructure of 11 S gels were investigated.

RESULTS

The results showed that HPH at higher pressures led to the breaking of disulfide bonds of aggregates and disrupted non-covalent interactions in protein aggregates, leading to collisions between protein aggregates and the reduction of large protein aggregates. High-pressure homogenization treatment at 60 MPa improved the gel properties of 11 S more. The HPH combined with heating changed the binary and tertiary structure of 11 S soy globulin and enhanced the hydrophobic interaction between 11 S molecules, thus improving the gel properties of 11 S. The change in intermolecular forces reflected the positive effect of HPH treatment on the formation of denser and more homogeneous protein gels.

CONCLUSION

In conclusion, high-pressure homogenization combined with heating can improve the properties of 11 S gels by changing the structure of 11 S protein, providing data and theoretical support for soy protein processing and its further applications. © 2022 Society of Chemical Industry.

Structural Analysis and Study of Gel Properties of Thermally-Induced Soybean Isolate-Potato Protein Gel System

Heat-induced composite gel systems consisting of different soybean protein isolate (SPI) and potato protein (PP) mixtures were studied to elucidate their "backbone" and property changes. This was achieved by comparing the ratio of non-network proteins, protein subunit composition, and aggregation of different gel samples. It was revealed that SPI was the "gel network backbone" and PP played the role of "filler" in the SPI-PP composite gel system. Compared with the composite gels at the same ratio, springiness and WHC decrease with PP addition. For hardness, PP addition showed a less linear trend. At the SPI-PP = 2/1 composite gel, hardness was more than doubled, while springiness and WHC did not decrease too much and increased the inter-protein binding. The hydrophobic interactions and electrostatic interactions and hydrogen bonding of the SPI gel system were enhanced. The scanning electron microscopy results showed that the SPI-based gel system was able to form a more compact and compatible gel network. This study demonstrates the use of PP as a potential filler that can effectively improve the gelling properties of SPI, thus providing a theoretical basis for the study of functional plant protein foods.

High intensity ultrasound-assisted quality enhancing of the marinated egg: Gel properties and in vitro digestion analysis

In this study, high intensity ultrasonication (HIU) was employed as an efficient tool to improve the gel property and in vitro digestibility of marinated egg (ME). The effects of HIU treatment at 100 W and 200 W for a series of time periods (0.5 h, 1 h, and 2 h) on the textural profiles, structural changes, and microstructures were also studied. After HIU treatment, the springiness and gumminess of ME white were enhanced. The water holding capacity reached the highest point (66.6%) when 0.5 h 200 W HIU was used. It was observed that 100 W HIU led to the highest zeta potential (-12.0 mV) and hydrophobicity (175.35 μg) of ME, indicating a high degree of electrostatic repulsion prevented agglomeration. HIU treatment at 100 W affected the dynamic rheological behaviors by boosting non-covalent bonds, which maintains the gel network's homogeneity. Meanwhile, the decreasing formation of α-helix, in contrast to β-turn, altered the aggregation behaviors of egg white gel. The microstructure of the 200 W HIU treated samples had porous colloidal network structures, and the in vitro digestibility (>75%) was increased after HIU. This work demonstrated that HIU could be a green and cost-effective tool for processing the egg product with high quality.

Effect of acetylated distarch adipate on the physicochemical characteristics and structure of shrimp (Penaeus vannamei) myofibrillar protein

To investigate the effect of acetylated distarch adipate (ADA) on the physicochemical properties and structure of shrimp myofibrillar protein (MP), the changes in chemical bonds, secondary structure and protein composition of shrimp MP and MP gel (MPG) were analyzed. Besides, the microstructure, water state, texture properties and water holding capacity (WHC) of MPG with different ADA additions were compared. The results showed that the shrimp MPG with 1% ADA addition had the highest breaking force and gel strength, WHC, and the densest three-dimensional network structure. The ADA had little significant effect on the secondary structure of MP and MPG. In addition, hydrogen and ionic bonds were the main chemical bonds of MP, while MPG is mainly dominated by hydrophobic and disulfide bonds. The correlation analysis of gel properties and water state of MPG showed that bound water and immobilized water had a positive effect on the gel strength.

Role of Food Hydrocolloids as Antioxidants along with Modern Processing Techniques on the Surimi Protein Gel Textural Properties, Developments, Limitation and Future Perspectives

Texture is an important parameter in determining the quality characteristics and consumer acceptability of seafood and fish protein-based products. The addition of food-based additives as antioxidants (monosaccharides, oilgosaccharides, polysaccharides and protein hydrolysates) in surimi and other seafood products has become a promising trend at an industrial scale. Improvement in gelling, textural and structural attributes of surimi gel could be attained by inhibiting the oxidative changes, protein denaturation and aggregation with these additives along with new emerging processing techniques. Moreover, the intermolecular crosslinking of surimi gel can be improved with the addition of different food hydrocolloid-based antioxidants in combination with modern processing techniques. The high-pressure processing (HPP) technique with polysaccharides can develop surimi gel with better physicochemical, antioxidative, textural attributes and increase the gel matrix than conventional processing methods. The increase in protein oxidation, denaturation, decline in water holding capacity, gel strength and viscoelastic properties of surimi gel can be substantially improved by microwave (MW) processing. The MW, ultrasonication and ultraviolet (UV) treatments can significantly increase the textural properties (hardness, gumminess and cohesiveness) and improve the antioxidative properties of surimi gel produced by different additives. This study will review potential opportunities and primary areas of future exploration for high-quality surimi gel products. Moreover, it also focuses on the influence of different antioxidants as additives and some new production strategies, such as HPP, ultrasonication, UV and MW and ohmic processing. The effects of additives in combination with different modern processing technologies on surimi gel texture are also compared.

Effects of High Hydrostatic Pressure on the Conformational Structure and Gel Properties of Myofibrillar Protein and Meat Quality: A Review

In meat processing, changes in the myofibrillar protein (MP) structure can affect the quality of meat products. High hydrostatic pressure (HHP) has been widely utilized to change the conformational structure (secondary, tertiary and quaternary structure) of MP so as to improve the quality of meat products. However, a systematic summary of the relationship between the conformational structure (secondary and tertiary structure) changes in MP, gel properties and product quality under HHP is lacking. Hence, this review provides a comprehensive summary of the changes in the conformational structure and gel properties of MP under HHP and discusses the mechanism based on previous studies and recent progress. The relationship between the spatial structure of MP and meat texture under HHP is also explored. Finally, we discuss considerations regarding ways to make HHP an effective strategy in future meat manufacturing.

Enhanced gelling performance of oxhide gelatin prepared from cowhide scrap by high pressure-assisted extraction

In this study, the feasibility of preparing oxhide gelatin from cowhide scrap by high pressure assisted-liquid extraction was verified. Different processing conditions, including high pressure time (15 to 25 min), pressure (250 to 350 MPa), and liquid-to-solid ratio (1:3 to 1:5), were optimized through response surface methodology. Under the optimum manufacturing conditions, when the high-pressure processing (HPP) time was 22 min, the pressure was 289 MPa, and the liquid-to-solid ratio was 1:4, the highest extraction yield (36%) and gel strength (224 g) were achieved. Based on DSC, XRD, FTIR, SEM, gelling and melting temperatures, HPP led to the structural modification of the gelatinized collagen, which enhanced the rearrangement of the gel structure during the gelation process and made it have better gelling properties. In addition, compared with the commercial sample, they do not differ significantly in the relaxation time and peak area of prepared oxhide gelatin. These findings provide new insights into the practicability of HPP during the preparation of oxhide gelatin, which can noticeably reduce the processing time and be applied to industrial production. PRACTICAL APPLICATION: Compared with traditional processing, a high pressure-assisted extraction process can noticeably reduce the processing time while producing cowhide gelation with similar physicochemical and functional properties. Meanwhile, high pressure processing (HPP) led to the structural destruction of the cowhide and gelatinized collagen, which enhanced the rearrangement of the gelatin structure during the gelation process and made it have better gelling properties. Importantly, high pressure-assisted extraction can facilitate the use of a low-cost raw material and improve the preparation efficiency of oxhide gelatin, which shows great potential in large-scale and efficient industrial production and the quality control of oxhide gelatin.

Effect of laver powder on textual, rheological properties and water distribution of squid (Dosidicus gigas) surimi gel

In order to ameliorate the gel quality of Dosidicus gigas surimi, the effects of laver powder on gel properties, rheological properties, and water-holding capacity (WHC) were investigated. Results indicated that the addition of laver powder could significantly increase the hardness, chewiness, and breaking force of surimi gels. However, the texture indexes and gel strength began to decline when additional amount exceeded 0.6%. Rheological results demonstrated that the addition of laver powder increased the storage modulus (G') and viscosity of surimi, prolonged protein denaturation temperature in surimi gels. Moreover, the WHC of surimi gel was improved with the increase of laver powder. Further analyses in low-field nuclear magnetic resonance revealed that laver powder could shorten the transverse relaxation time, enhanced the combination with water, and altered the distribution of different water categories. The proportion of bound water and immobilized water reached its maximum and minimum at 0.6% of laver powder, respectively. Correlation analyses showed that WHC of surimi gel was negatively correlated well with the proportion of loose-bound water, but positively correlated with the strong-bound water and free water. In conclusion, the results supported that 0.6% was the optimal additional amount of laver powder for the squid-based surimi production based on the current ingredients of surimi products.