Combined effect of microbial transglutaminase and ethanolic coconut husk extract on the gel properties and in-vitro digestibility of spotted golden goatfish (Parupeneus heptacanthus) surimi gel

Comparative studies on microbial transglutaminase, complex phosphate and fructooligosaccharide interacts with myofibrillar proteins: Improvement of the quality and flavor of silver carp surimi

The aim of this study was to evaluate the effect of microbial transglutaminase (MTG), complex phosphate (CP) and fructooligosaccharide (FOS) interact with myofibrillar proteins (MPs) on the quality and flavor of silver carp surimi gels. When surimi was added with 0.3 % MTG, 0.3 % CP and 4 % FOS respectively, the gel strength and texture were superior to those of the control group, and the surimi microstructure became more compact with smaller pore sizes. This was because MTG can induce the ε-(γ-glutamate) lysine bond formation in surimi MPs and promotes cross-linking of MPs. CP can increase the ionic strength, FOS can form hydrogen bonds with water and enhance MPs hydration, both of them promoted the conversion of α-helix to β-folding of MPs, and facilitate the formation of disulfide bonds. 13 volatiles were identified in control group, whereas the number of volatiles was increased to 31, 22 and 22 after addition of MTG, CP and FOS respectively, suggesting that MTG, CP and FOS promoted lipid oxidation and interacted with MPs to produce volatile compounds. Therefore, the addition of MTG, CP and FOS improved the quality and flavor of chub surimi gels, with MTG having the greatest effect on surimi.

Impacts of zein-fucoidan nanoparticles with and without curcumin on gel properties of golden threadfin bream (Nemipterus virgatus) surimi

Zein-fucoidan nanoparticles (ZFNPs) as an excellent colloidal delivery system for bioactive compounds, such as curcumin (CUR), show a great application potential in the food industry. Herein, various amount of ZFNPs, ZFNPs loaded with CUR (CZFNPs) and free CUR were added into golden threadfin bream (Nemipterus virgatus) surimi to explore their impacts on the gel properties. Dynamic rheological tests showed that storage modulus (G') and loss modulus (G") of surimi gels with the additive amount of ZFNPs and CZFNPs under 0.8 % significantly increased and their loss tangent (tan δ) slightly reduced during thermal gelation, indicating stronger networks and better structural configuration. Puncture test and textural profile analysis confirmed the improvements in breaking force, hardness, chewiness and gumminess of surimi gels. Furthermore, 0.8 % of ZFNPs and CZFNPs induced conformational changes of surimi proteins from α-helix to β-sheet and random coil, and then facilitating the cross-link between proteins. Low-field nuclear magnetic resonance revealed that ZFNPs and CZFNPs promoted the redistribution of water in surimi gel networks, converting more free water to tightly bounded water, and thus increasing the water holding capacity. However, the addition of equivalent amount of CUR caused detrimental to surimi gel properties. In conclusion, ZFNPs and CZFNPs conferred better gel properties and nutritional characteristics to surimi gels, and this study provided a theoretical basis for the development of high-quality surimi products.

Correlations of Gelling Properties and 3D Printability to the Chemical Composition and Rheological Properties of Surimi from Different Marine Fish Species

Samples of marine surimi made from six different fish types have been comprehensively investigated and compared in terms of chemical composition, protease activity, gelling chemistry, gel properties and 3D printability. It has been found that surimi with high protein content, low fat concentration, low activity of endogenous protease (cathepsin B, cathepsin L, cathepsin D, calpain and serine protease) and low TVB-N showed better gelling capacity and gel properties. However, the 3D printability of surimi was more relevant to apparent viscosity. The surimi with viscosity between 5000 Pa·s and 12,000 Pa·s yielded better printing performance as indicated by higher printing accuracy than 97% and less cooking loss. This study clarified the effects of marine fish types on the corresponding surimi gelation and gel properties, and successfully established relationships between surimi properties and 3D printing performance, thus providing new insights on exploring new surimi sources and developing 3D surimi printing techniques.

Effect of denaturation rate of sliver carp myosin induced by alcohols on its thermal aggregation behavior and gel properties

The effects of ethanol, 1,2-propanediol, and glycerol at concentrations from 10 % to 40 % on the thermal denaturation and aggregation of silver carp (Hypophthalmichthys molitrix) myosin were investigated. The results revealed that ethanol and 1,2-propanediol induced thermal denaturation of myosin more rapidly than glycerol, which minimally impacted the secondary structure. At 10 % concentration, 1,2-propanediol significantly influenced myosin's secondary structure more than ethanol. While at a concentration of 20 %, ethanol prompted faster thermal denaturation and aggregation, resulting in higher turbidity than 1,2-propanediol (P < 0.05). Notably, higher concentrations of ethanol (30 % and 40 %) and 1,2-propanediol (40 %) induced the formation of non-disulfide covalent bonds, contributing to excessive myosin aggregation. Furthermore, hydrophobic interactions emerged as crucial within myosin aggregation in glycerol solutions during heating. Additionally, the effects of three alcohols at 1 %, 3 %, and 5 % on the gel properties were investigated. The results showed that an appropriate concentration of 1,2-propanediol (3 %) and glycerol (5 %) significantly enhanced the gel properties by inducing desirable unfolding and aggregation of myosin molecules. These findings offer a theoretical foundation for utilizing alcohol additives to enhance the gel quality of heat-induced surimi.

Factors influencing surimi gelling properties and natural additive-based gel fortification strategies: A review

Gelation and gel properties are crucial to surimi-based seafood products, and many factors significantly influence surimi gel quality. Although physical and chemical modifications can improve surimi gel performance, challenges such as high cost, difficulties in industrialization and environmental pollution pose significant barriers to their practicality. Natural additives offer a promising alternative by reinforcing and improving the characteristics of surimi gel through mechanisms such as protein conformational transformation, protein denaturation, and altered chemical forces. By incorporating different substances into surimi gel, it is possible to tune the interaction between the additives and the myofibrillar proteins, thus enhancing the gelation process and achieving the desired textural profiles. This review comprehensively explored the factors influencing the surimi gelation chemistry, with a focus on how the natural additives such as proteins, lipids, polysaccharides, salts, enzymes, and extracts impact the surimi gel properties. It elucidated the reinforcing mechanisms of these additives and proposed a general interaction model between natural substance and myofibrillar proteins. Furthermore, this review well established the interrelation between the performance and mechanism of enhancement effects of typical natural substances on surimi gels and provided new insights on tuning surimi gelation and gel properties by adding natural additives with specific physicochemical properties, thus facilitating the production of high-quality surimi products with satisfactory gel characteristics in food industry.

Effect of α-tocopherol, soybean oil, and glyceryl monostearate oleogel on gel properties and the in-vitro digestion of low-salt silver carp (Hypophthalmichthys molitrix) surimi

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.

Effects of different protein cross-linking degrees on physicochemical and subsequent thermal gelling properties of silver carp myofibrillar proteins sol subjected to freeze-thaw cycles

Knowledge regarding the denaturation process and control methods for depolymerized sol-state myofibrillar proteins (MPs) during freezing remains scant. This study investigated the effects of protein cross-linking treatment before freezing on physicochemical and subsequent gelation properties of MPs sol subjected to freeze-thaw (F-T) cycles. Results indicated that after five F-T cycles, cross-linked MPs sols showed increased high molecular weight polymers and bound water (T21a and T21b) mobility, suggesting enhanced protein-protein interactions at the expense of protein-water interactions. Upon heating after F-T cycles, gels formed from cross-linked sols exhibited significantly higher hardness, springiness, and cooking loss (P < 0.05), alongside more contracted gel networks. Correlation analysis revealed that the formation and properties of thermal gel after freezing closely relate to changes in molecular conformation and chemical bonds of cross-linked MPs sol during freezing. This study provides new insights into regulating the freezing stability and post-thawed thermal processing properties of sol-based surimi products.

Enhancing gel behavior of yellow croaker surimi by fruit extracts: Physicochemical properties and molecular mechanism

The aim of this study was to investigate the effects of grape seed extract (GSE), acerola cherry extract (ACE), and blueberry extract (BBE) on the physicochemical properties and structure of the yellow croaker surimi gel. In addition, molecular docking and molecular dynamics (MD) simulation were utilized to study the binding mechanism of yellow croaker's fibrillin and fruit extracts. Surimi gel with 1.5% GSE, ACE, and BBE had the highest water holding capacity, hardness, chewability, cohesion, breaking force, breaking distance, gel strength, and densest 3D network structure, according to the experiment's findings. Nevertheless, the cross-linking of proteins in surimi was blocked with the further increase of fruit extract (1.5%-2.0%), and the existing network of surimi was weakened or even destroyed. Three fruit extracts had little effect on the secondary structure of the surimi gel. Besides, hydrophobic and disulfide bonds are the main chemical bonds of croaker surimi. Molecular docking showed that B-type procyanidine (BP) interacted with ASN-183, SER-571, ASP-525, ARG-350, LYS-188, GLU-349, CYS-353, and other active amino acids in croaker protein. Moreover, it can form strong hydrogen bond interaction with ASN-183, SER-571, ASP-525, and ARG-350 at the active sites of protein. The BP-Larimichthys crocea protein system's MD simulation was carried out, and calculations for the simulation's root mean square deviation, root mean square fluctuation, radius of gyration, solvent accessible surface area, and hydrogen bonds were made. It was found that these indices can demonstrate that the BP binding contributes to the stability of the yellow croaker structure.

Single Ultrasonic-Assisted Washing for Eco-Efficient Production of Mackerel (Auxis thazard) Surimi

This study highlights a promising single washing method for producing dark-fleshed mackerel surimi aided by ultrasonication in conjunction with cold carbonated water containing 0.6% NaCl and mixed antioxidants (0.5% EDTA/0.2% sodium erythorbate/0.2% sodium tripolyphosphate) (CSA). Different washing periods (5, 10, and 15 min) with and without ultrasound were tested. Unwashed mince (A1) and conventional water-washed surimi (10 min/cycle, 3 cycles) (A2) were used as controls. A3, A4, and A5 were subjected to ultrasound-assisted washing for 5, 10, and 15 min, respectively, whereas A6, A7, and A8 had non-ultrasound-assisted washing for 5, 10, and 15 min. Results showed that the surimi yield decreased as the ultrasonic treatment time increased from 5 to 15 min (p < 0.05). Increased ultrasonic time resulted in greater protein denaturation, protein oxidation, myoglobin removal, and lipid oxidation in surimi (p < 0.05). Surimi produced by CSA ultrasonication for 5 min (A3), on the other hand, had a comparable overall quality to A2 surimi (p > 0.05). The correspondence gel (A3) outperformed the control gel (A2) in terms of gel strength, whiteness, and water-holding capacity (p < 0.05). The formation of regularly continuous, more organized, and smooth network structures in surimi gel was observed in A2 and A3 gels, whereas sparse and larger pore sizes were noticed in surimi gels produced by longer ultrasonic treatment. All of the surimi gels had identical FTIR spectra, indicating that the functional groups of the protein gel were consistent throughout. As a result, a single 5 min CSA-ultrasonic washing could potentially yield surimi of comparable quality to conventional washing. This could pave the way for the development of dark-fleshed fish surimi, which would require less washing time and produce less waste water.

Gelation characteristics of partially purified myofibrillar proteins extracted from commercially harvested Indian mackerel and threadfin bream

Gelling behaviors of partially purified myofibrillar proteins (PPMP) extracted from Indian mackerel (IM) and threadfin bream (TB) as a function of heating temperatures (20-75°C) were comparatively studied. PPMP obtained from IM (IM-MP) showed lower turbidity and surface hydrophobicity as compared to those extracted from TB (TB-MP). Moreover, lower disulfide bond content was noticed in IM-MP (7.7-9.46 mol/106  g protein) as compared to TB-MP (10.99-13.95 mol/106  g protein) during the heating process. There was no major difference in the amino acid profile noticed between PPMP from both the species, except lysine and glutamine contents, which were higher in TB-MP. Structural analysis, FTIR spectra, amide I band, and fluorescence intensity substantiated those changes. The protein pattern also revealed autolysis of IM-MP. The transmission analysis also showed lower aggregation and crosslinking ability of IM-MP than TB-MP. Therefore, poorer gelling behavior of IM-MP reconfirmed the inferior gel property of surimi gel from IM to gel from TB. Potential development is still required for the improvement of the gel properties of dark-fleshed fish surimi such as IM. PRACTICAL APPLICATION: Indian mackerel (IM) is an abundant and widely captured fish species. Due to overexploitation of lean fish, pelagic fish could be explored as a potential raw material for surimi production. However, poor gelling properties of IM limit its use in the surimi industry. This study provides an insight into the gelling behavior of myofibrillar proteins from IM during the gelation process in comparison with the lean fish (threadfin bream). Overall, structural and rheological changes of myofibrillar proteins play a role in gelation, thus affecting gel properties between two species. Further improvement of the gel of IM is still required.

Effects of anthocyanins and microbial transglutaminase on the physicochemical properties of silver carp surimi gel

The objective of this study was to investigate effects of anthocyanins (AC) and microbial transglutaminase (MTGase) on the physicochemical properties of surimi gels from silver carp. The addition of AC and MTGase significantly increased gel strength and water holding capacity (WHC) of surimi gels, but the effect of MTGase was much stronger (p < .05). There were the highest gel strength, storage modulus (G') and WHC with 0.1 g/100 g AC and 0.4 g/100 g MTGase, while they were higher than that with AC or MTGase alone. AC promoted the cross-linking mainly by covalent and non-covalent bonds in surimi gels, while MTGase did mainly through covalent bonds. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) confirmed the results of gel strength, WHC, chemical interactions and G' of surimi gel or paste with AC and MTGase. In general, AC and MTGase could synergistically improve the physicochemical properties of surimi gels and potentially enhance the quality of surimi-based product from silver carp.

Ultrasound-assisted processing: Changes in gel properties, water-holding capacity, and protein aggregation of low-salt Hypophthalmichthys molitrix surimi by soy protein isolate

The effects of ultrasound combined (25 kHz, 400 ± 20 W/L, ultrasonic time of 5, 10 and 15 min) with soy protein isolate processing on gelling properties of low-salt silver carp surimi, aggregation and conformation of myofibrillar protein were investigated. The results revealed that, compared with only adding soy protein isolate components, ultrasound-assisted soy protein isolate had a more obvious effect on the protein structure in low-salt surimi, leading to the decrease in α-helix and total sulfhydryl contents, and the increase in β-sheet content and protein solubility. As a result, more proteins participated in the formation of the gel network, and significant improvements in hardness, gel strength and water-holding capacity of the low-salt surimi gel were observed, while the myosin heavy chain in SDS-PAGE was weakened. The low-field NMR results showed that the initial relaxation time of T₂ was apparently shorter, the free water content decreased and the bound water content increased under the action of ultrasound. Scanning electron microscope observation found that the surimi gel treated by ultrasound exhibited smaller holes, and had a more stable and denser network structure. In conclusion, the results of our work demonstrated that ultrasound combined with soy protein isolate can significantly improve the gel quality properties of low-salt silver carp.

Effects of Potato Protein Isolated Using Ethanol on the Gelation and Anti-Proteolytic Properties in Pacific Whiting Surimi

Pacific whiting is a primary species utilized for surimi processing in the Pacific Northwest of the US. However, endogenous protease in Pacific whiting surimi deteriorates the quality during slow cooking. The demand for clean-labeled and economically competitive protease inhibitors has been increasing. In the present study, the anti-proteolytic effect of potato protein isolate (PPI), a by-product from the potato starch industry, prepared using 20% ethanol on the endogenous protease activity of Pacific whiting (PW) surimi was investigated. The ohmic heating method was carried out for a better assessment of the anti-proteolytic activity of inhibitors. A factorial design was carried out in which the independent variables were the four types of inhibitors and their concentration (0, 0.5, 1, 2, and 3% w/w) at two heating conditions. The heating condition was used as a blocking factor. All experiments were randomized within each block. The addition of 2% PPI which demonstrated the highest anti-proteolytic activity among five different concentrations significantly increased the breaking force, penetration distance, and water retention ability of PW surimi gel as the endogenous proteases were effectively inhibited when heated ohmically at 60 °C for 30 min prior to heating up to 90 °C. In addition, SDS-PAGE disclosed that PPI successfully retained the intensity of myofibrillar heavy chain (MHC) protein of PW surimi gels even under the condition at which proteases could be activated at 60 °C. The whiteness of gels was not negatively affected by the addition of PPI. Comparing all samples, a denser and more ordered microstructure was obtained when PPI was added. A similar trend was found from the fractal dimension (Df) of the PPI-added gel’s microstructure. Therefore, PPI could be an effective and non-allergenic protease inhibitor in PW surimi leading to retaining the integrity of high gel quality.

Characteristics and qualities of edible bird's nest beverage as affected by thermal pasteurization and sterilization

Edible bird's nest beverage (B-nest-Bev) was produced from edible bird's nest (B-nest) flakes using different thermal processes. Pasteurization of B-nest-Bev at a low temperature for a longer time (LTLT) or at a high temperature for a shorter time (HTST) resulted in lower CIE L * , CIE a * , CIE b * -values, and drained weight (p < 0.05) than sterilization (118 or 121 °C). Sterilized and pasteurized B-nest-Bev had similar soluble solid contents and pH (p < 0.05). Nevertheless, acidified beverages pasteurized via either LTLT or HTST process had a marked decrease in sialic acid content. In addition, drastic protein degradation occurred in pasteurized acidified beverages, regardless of the conditions used, ascertained by the disappearance of major protein bands. However, polymerization of proteins took place in sterilized samples, irrespective of the temperature used. After digestion in a gastrointestinal tract model system (GIMs), all samples had increased (p < 0.05) antioxidant activities including DPPH and ABTS radical scavenging activities, ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). B-nest-Bev subjected to HTST pasteurization or sterilization at 121 °C had the best appearance and acceptability among all the treatments used. Therefore, thermal processes directly affected the properties and acceptability of B-nest-Bev.

Compare with different vegetable oils on the quality of the Nemipterus virgatus surimi gel

To enhance the quality and flavor of surimi-based products, we investigated the effects of vegetable oils (peanut, soybean, corn, coconut, olive, and safflower seed oils) on the texture, water-holding capacity (WHC), microstructure, and flavor of the Nemipterus virgatus surimi gel. The results showed that 6 kinds of vegetable oils could improve the whiteness and flavor of gels. However, peanut, olive, and coconut oils enriching oleic acid or lauric acid were easy to accumulate with an average diameter of more than 0.15 μm. Thus, the gel with the oil showed a loose network structures with large cavities, and the texture was deteriorated, accompanied by decreased WHC (p < .05). Compared with other vegetable oils, soybean, corn and safflower seed oils enriching linoleic acid were emulsified with protein forming a stable interfacial protein film. The gel with the oil showed an increase in the WHC and bound water content. Furthermore, the oil droplets with an average diameter of less than 0.15 μm were evenly distributed in the gel matrix, and the gel exhibited dense network structures with small cavities and smooth surface. In general, soybean and safflower seed oils can be used as a potential additive to improve the quality and flavor of surimi-based products.

Effect of sodium bicarbonate on textural properties and acceptability of gel from unwashed Asian sea bass mince

Asian sea bass mince gels having different adjusted moisture/water content (80 and 85%; w/w) were prepared with addition of sodium bicarbonate (SB) at various concentrations (0, 0.05 and 0.1%; w/w). Fish mince gels of 80% water content added with 0.05 and 0.1% SB (G80-0.05 and G80-0.1, respectively) had the highest increase (135-139%) in breaking force (BrF) than the respective control gel (G80) (P < 0.05). For gel with 85% water content, a lower increase (17-28%) in BrF was found with the addition of SB as compared to their corresponding control (G85). Whiteness of all samples was continuously decreased with increasing amount of SB, however the water holding capacity was increased drastically with augmenting levels of SB, regardless of the water content (P < 0.05). A loss in the elasticity of gel was attained with the addition of SB as indicated by decreasing storage modulus. A finer and more compact network was detected in a gel containing SB, irrespective of water content. Based on sensory scores, gel having 85% water content added with 0.05 and 0.1% SB had similar acceptability to the control gel (G80) containing 80% water content (commercial level). Therefore, SB at the appropriate level could improve the gelling properties with higher water holding ability of the mince gel with high acceptability.

Threadfin bream surimi gel containing squid fin protein hydrolysate: Textural properties, acceptability, and volatile profile

Gel properties of threadfin bream surimi gels with squid fin protein hydrolysate (SFPH) at various concentrations (0, 1, 2, 3, and 4%; w/w) were determined. The gel without SFPH (CON) had the highest breaking force (BrF) and deformation (DeF) as compared to those with SFPH (p < 0.05). Among the gel with SFPH, gel containing 1 and 2% SFPH (SFPH-1 and SFPH-2, respectively) had the highest BrF, whereas the lowest value was obtained when 4% SFPH was used (SFPH-4) (p < 0.05). The whiteness of all samples was slightly decreased with an upsurging amount of SFPH. However, water holding capacity was increased with augmenting levels of SFPH (p < 0.05). Sensory analysis revealed that SFPH-2 had a higher squid odor and flavor likeness score than CON (p < 0.05). Textural properties, especially hardness, were decreased with increasing SFPH, except for SFPH-1 and SFPH-2 (p > 0.05). In addition, the rheological properties, microstructure, and volatile profile of the selected surimi gel were also studied. The storage modulus (G') of SFPH added samples was decreased as compared to the CON sample. The CON gel had a finer and more compact network as compared to SFPH-2 and SFPH-4 samples. Volatile profiles indicated that alcohols, carboxylic acids, ketones, and ether were the major volatile compounds present in both gel samples. Furthermore, thiophene, 3-methyl-, contributing to squid flavor, was found in the SFPH-2 sample. Overall, SFPH at 2% could act as a flavorant in the threadfin bream surimi gel without markedly negative impact on gelling and textural properties, while providing squid odor and flavor to the resulting gel. PRACTICAL APPLICATION: The various low-valued byproducts generated from the squid processing industry could result in various environmental problems. Those byproducts are rich in various biomolecules such as proteins, fats, enzymes, and so forth, which could be utilized to produce value-added products. Among them, protein hydrolysate (PH) rich in amino acids with excellent antioxidant properties could serve as an alternative flavorant. Therefore, PH from squid byproducts, especially fins, could be applied in foods such as fish balls, surimi gels, and so forth to enhance the nutritional and flavoring profile of a finished product. Moreover, bioactive peptides in PH with antioxidant potential could retard the oxidation of proteins and lipids.

Asian Carp, an Alternative Material for Surimi Production: Progress and Future

Asian carp is a general designation for grass carp, silver carp, bighead carp, and black carp. These fish species belong to the family Cyprinidae. In 2018, more than 18.5 million tons of Asian carp were produced globally. Asian carp can be used for producing surimi, a stabilized myofibrillar protein concentrate that can be made into a wide variety of products such as imitation crab sticks, fish balls, fish cakes, fish tofu, and fish sausage. Surimi is usually made from marine fish, but Asian carp have been widely used for surimi production in China. The quality of surimi is affected by various factors, including the processing methods and food additives, such as polysaccharides, protein, salt, and cryoprotectant. With an impending shortage of marine fish due to overfishing and depletion of fish stocks, Asian carp have a potential to serve as an alternative raw material for surimi products thanks to their high abundancy, less emissions of greenhouse gases from farming, desirable flesh color, and sufficient gel forming ability. The utilization of Asian carp in surimi production could also contribute to relieving the overflow of Asian carp in the United States.

Freeze-Thawing Treatment as a Simple Way to Tune the Gel Property and Digestibility of Minced Meat from Red Swamp Crayfish (Procambarus clarkiix)

The effects of freezing methods, including rapid freezing (RF) or slow freezing (SF), combined with thawing methods, e.g., water immersing thawing (WT) or cold thawing (CT), on the meat yield, drip loss, gel properties, and digestive properties of meat detached from red swamp crayfish were investigated. RF greatly reduced the freezing time compared to SF, and the thawing time of frozen crayfish was obviously shortened by WT in comparison to CT. RF and CT improved the meat yield but increased the drip loss, probably as a result of the greater protein denaturation or degradation. A soft and flexible gel was obtained by SF-CT, while a hard one was achieved by RF-WT. An SEM analysis showed that SF resulted in rough and irregular microstructures with larger pore sizes. Freeze-thawing led to an increase in the β-sheet content at the expense of α-helix and variations in the microenvironment of tyrosine and tryptophan residues in protein molecules of the gels, which was more pronounced in the SF-CT group. Moreover, freeze-thawing could cause enhanced protein digestibility but reduce the antioxidant activity of gels. These findings underline the promise of the freezing-thawing treatment in tuning the gel-based meat products of crayfish.

Gelation properties and protein conformation of Grass Carp fish ball as influenced by egg white protein

Dried egg white powder (EWP) and purified ovalbumin (OVA, 98%) were used as supplements to improve grass carp (GC) fish balls (FB) quality. The effects of EWP and/or OVA contents on the gel strength, water holding capacity (WHC), moisture migration and distribution, and rheological properties of GC-FB, as well as on myofibrillar protein (MfP) structures in the GC-FB were evaluated. The results showed that with the increase of EWP addition from 0 to 4% (w/w), the gel strength and WHC of the GC-FB samples were increased from 34.28 to 66.63 N×mm, and 83.02 to 88.36%, respectively, but the increases were insignificant between 3% and 4% EWP-added GC-FBs (p>0.05). As the EWP increased, the T₂ relaxation time shifted towards lower values, indicating a general decline in water mobility. The effects of EWP on rheological properties were insignificant. Addition of OVA and/or EWP led to changes in secondary structural units in the FB, with α-helix (27.53%) reaching the highest value in OVA-added GC-FB, β-sheet (46.07%) reaching the highest value in GC-FB, and β-turn (33.54%) reaching the highest value in EWP-added GC-FB, respectively. Raman spectroscopy revealed that OVA-added GC-FB had the lowest hydrophobic interlinkages. Protein pattern analysis suggested that the OVA (1.58%) might contribute to the decrease in the myosin heavy chain (MHC) band intensity through cross-linked with MfP. These results suggested that EWP could improve the quality of GC-FBs and OVA played an important role with MfP gelation. This article is protected by copyright. All rights reserved.

Independent and combined effects of ultrasound and transglutaminase on the gel properties and in vitro digestion characteristics of bay scallop (Argopecten irradians) adductormuscle

The effects of transglutaminase (TGase) addition (0.4–1.2 g/100g), ultrasound (120–720 W, 20 min), and their combination on the gel properties and in vitro digestion characteristics of bay scallop adductor muscle were studied. The gel strength of the gel sample with TGase content of 0.8 g/100g (TG-0.8) was 58.2% higher than that of the control sample (CON). The gel sample treated with ultrasound at 480 W (UT-480) had the highest gel strength. The strength of the gel prepared by combination of 0.8 g/100g TGase and 360 W ultrasound (UT-TG) was 82.3% higher than that of CON. The whiteness and water holding capacity of the gel increased regardless of the addition of TGase or ultrasound treatment. SDS-PAGE patterns showed that the myosin heavy chain of the treated samples became thinner, and the changes of actin and tropomyosin were not significant. The scanning electron microscopy results of gel samples prepared by ultrasound combined with TGase showed a denser structure, which was related to the lowest total sulfhydryl content and TCA-soluble peptide content. The results of dynamic rheology show that the UT-TG sample had the highest G′ value, followed by TG-0.8. The in vitro digestion characteristics of the selected gel samples were also discussed. The degree of protein hydrolysis and the content of free amino acids in TG-0.8 samples were the lowest, which improved after ultrasound treatment. Overall, the combination of appropriate ultrasound treatment and TGase addition provides an effective means for improving gel properties and digestibility of scallop surimi product.

•

Ultrasound and TGase enhanced gel properties of bay scallop adductor muscle (BSM).

•

Ultrasound-assisted treatment promoted the cross-linking of BSM myosin by TGase.

•

A denser gel network structure was formed when ultrasound combined with TGase.

•

Ultrasound combined with TGase can improve the digestibility of the gel in vitro.

Effect of Psyllium (Plantago ovata Forks) Husk on Characteristics, Rheological and Textural Properties of Threadfin Bream Surimi Gel

Effects of psyllium (Plantago ovata) husk powder (PHP) at various concentrations (0, 1, 2, 3 and 4%, w/w) on gelling properties of surimi from threadfin bream (Nemipterus sp.) were investigated. The addition of 1% PHP resulted in the highest increase (50%) in the breaking force (BF) of surimi gel (S), compared to that of the control gel (CON; without PHP). Lower BF was obtained for gel incorporated with PHP at the higher levels (2–4%) (p < 0.05). On the other hand, deformation (DF) was decreased with the addition of PHP at all levels compared to the CON gel. The whiteness and expressible moisture content of gels were decreased with augmenting levels of PHP (p < 0.05). Protein patterns revealed that PHP at all concentrations did not affect the polymerization of the myosin heavy chain. A loss in the elasticity of the gel was attained with the addition of PHP as indicated by decreased storage modulus (G’). A finer and more compact network was detected in gels containing 1 and 2% PHP than that found in the CON. FTIR spectra suggested that the addition of PHP influenced the secondary structure as well as functional groups of myofibrillar proteins. Based on the sensory evaluation, the surimi containing PHP at 1–3% showed a similar overall likeness score to the CON. Therefore, PHP at the optimum level could improve the gelling properties of the threadfin bream surimi with high acceptability.

Textural, Sensory, and Chemical Characteristic of Threadfin Bream (Nemipterus sp.) Surimi Gel Fortified with Bio-Calcium from Bone of Asian Sea Bass (Lates calcarifer)

The effects of Asian sea bass (Lates calcarifer) bio-calcium (ASBB) at different levels (0, 2, 4, 6, 8, and 10%) (w/w) on properties of threadfin bream (Nemipterus sp.) surimi gel were investigated. ASBB addition increased breaking force and deformation, while reduced expressible moisture content (p < 0.05) of surimi gel. L* (lightness), a* (redness), and b* (yellowness) values were increased with augmenting ASBB levels; however, whiteness slightly decreased in surimi gel incorporated with ASBB (p < 0.05). Higher likeness scores were noticed in surimi gel containing ASBB, compared to that of the control. However, a slight decrease in the likeness score was noticed in surimi gel with 10% (w/w) ASBB (p < 0.05). Surimi gel added with 8% (w/w) ASBB possessed the increase in breaking force by 80% from the control and had the highest likeness score. Texture profile analysis of surimi gel added with ASBB showed the improved texture characteristics with coincidentally higher storage modulus of surimi paste. Surimi gel with 8% (w/w) ASBB had a denser and finer microstructure with higher ash, calcium, and phosphorous contents, compared to the control. Thus, incorporation of bio-calcium up to 8% (w/w) not only increased mineral content, but also improved textural, sensory, and microstructural properties of surimi gel.

Myoprotein-phytophenol interaction: Implications for muscle food structure-forming properties

Phenolic compounds are commonly incorporated into muscle foods to inhibit lipid oxidation and modify product flavor. Those that are present in or extracted from plant sources (seeds, leaves, and stems) known as "phytophenols" are of particular importance in the current meat industry due to natural origins, diversity, and safety record. Apart from these primary roles as antioxidants and flavorings, phytophenols are now recognized to be chemically reactive with a variety of food constituents, including proteins. In processed muscle foods, where the structure-forming ability is critical to a product's texture-related quality attributes and palatability, the functional properties of proteins, especially gelation and emulsification, play an essential role. A vast amount of recent studies has been devoted to protein-phenol interactions to investigate the impact on meat product texture and flavor. Considerable efforts have been made to elucidate the specific roles of phytophenol interaction with "myoproteins" (i.e., muscle-derived proteins) probing the structure-forming process in cooked meat products. The present review provides an insight into the actions of phytophenols in modifying and interacting with muscle proteins with an emphasis on the reaction mechanisms, detection methods, protein functionality, and implications for structural characteristics and textural properties of muscle foods.

Effect of High Voltage Cold Plasma on Oxidation, Physiochemical, and Gelling Properties of Myofibrillar Protein Isolate from Asian Sea Bass (Lates calcarifer)

The effects of in-bag dielectric barrier discharge high voltage cold plasma (IB-DBD-HVCP) on myofibrillar protein isolate (MPI) from Asian sea bass (ASB) and its impact on the physiochemical and gelling properties of MPI gels were elucidated. A mixture of argon (90%) and oxygen (10%) was used for generating IB-DBD-HVCP. MPI was subjected to IB-DBD-HVCP for varying times (5–15 min). Total carbonyl content was increased, while total sulfhydryl content was decreased in MPI, especially with augmenting treatment time (TT) (p < 0.05). Surface hydrophobicity initially increased when IB-DBD-HVCP TT of 5 min (DBD-HVCP5) was implemented, followed by subsequent decrease with increasing TT. Based on gel electrophoresis, lower actin and myosin heavy chain (MHC) band intensities were found for MPI subjected to IB-DBD-HVCP, particularly when a TT longer than 10 min was used, compared to those of the control. Gel made from DBD-HVCP5 had higher breaking force, deformation, and highest G′ value compared to others. A more ordered and fibrous network was found in DBD-HVCP5 treated gel. Therefore, IB-DBD-HVCP treatment, particularly for 5 min, enhanced cross-linking of proteins in ASB myofibrillar proteins, which resulted in the improved gel elasticity and strength.