Effect of κ-carrageenan on gelation and gel characteristics of Antarctic krill (Euphausia superba) protein isolated with isoelectric solubilization/precipitation

Insights into the Mechanism Underpinning Composite Molecular Docking During the Self-Assembly of Fucoidan Biopolymers with Peptide Nanofibrils

Composite hydrogels with improved mechanical and chemical properties can be formed by non-covalently decorating the nanofibrillar structures formed by the self-assembly of peptides with fucoidan. Nevertheless, the precise interactions, and the electrochemical and thermodynamic stability of these composite materials have not been determined. Here, we present a thermodynamic analysis of the interacting forces that drive the formation of a composite fucoidan/9-fluorenylmethoxycarbonyl-phenylalanine-arginine-glycine-aspartic acid-phenylalanine (Fmoc-FRGDF) hydrogel. The results showed that the co-assembly of fucoidan and Fmoc-FRGDF was spontaneous and exothermic. The melting point increased from 87.0 °C to 107.7 °C for Fmoc-FRGDF with 8 mg/mL of added fucoidan. A complex network of hydrogen bonds formed between the molecules of Fmoc-FRGDF, and electrostatic, hydrogen bond, and van der Waals interactions were the main interactions driving the co-assembly of fucoidan and Fmoc-FRGDF. Furthermore, the sulfate group of fucoidan formed a strong salt bridge with the arginine of Fmoc-FRGDF. This study provides useful biomedical engineering design parameters for the inclusion of other highly soluble biopolymers into these types of hydrogel vectors.

Composite cold-set gels of kidney bean protein isolate and basil seed gum induced by glucono-δ-lactone and sodium citrate: Preparation, gel properties and protection on astaxanthin

In this study, kidney bean protein isolate (KPI) and basil seed gum (BSG) thermal aggregates were prepared to form cold-set gels (KB) by adding sodium citrate (SC) and glucono-δ-lactone (GDL). The structure and gel properties of the cold-set gels were investigated. Results showed that the gels added with SC had higher water holding capacity and lower gel strength than GDL-induced gels. While the cold-set gels induced by GDL with the addition of SC (KB-GDL/SC) possessed compact gel network with higher viscoelasticity. Compared with KPI cold-set gels, the KB cold-set gels exhibited higher gel strength and greater capacity to capture water due to the filling and cross-linking effect of BSG, and its high hydrophilicity and changes on the KPI molecular structures. Moreover, the KB-GDL/SC presented a lower syneresis rate of 28.2 % than other gels after freeze-thaw treatment. Meanwhile, KB-GDL/SC showed better protection on astaxanthin under ultraviolet light or during heat treatment. All the KB cold-set gels controlled the release of astaxanthin during simulated digestion. Particularly for KB-SC, the loaded astaxanthin had the highest bioaccesssbility (24.5 %) after in vitro digestion. This study may provide unique insights for development of novel cold-set gels and related functional foods.

Polysaccharides as natural enhancers for meat quality, preservation, and protein functionality: A comprehensive review

Recent research focuses on developing meat products with health-promoting properties to reduce disease risk, particularly using natural polysaccharides due to their antioxidant and antibacterial effects. These polysaccharides, sourced from various materials, act through diverse structural mechanisms, inhibiting pathogen growth, enhancing oxidative stability, and improving meat flavor. This study highlights the role of meat proteins in achieving the Sustainable Development Goals (SDGs) and their importance in enhancing processed meat quality. It also examines the application of natural antioxidants and preservatives in meat processing. While some promising results demonstrate the potential of polysaccharides in meat science, their role in improving meat protein functions requires further investigation. Additionally, current solutions for improving meat quality face limitations, necessitating further research to reach industrial-scale applications. Thermal stability of meat proteins remains a critical factor throughout all stages of meat production, from processing and sterilization to consumption and preservation.

Pioneering application of Antarctic krill protein in astaxanthin steady-state delivery

Antarctic krill (Euphausia superba) protein, as a type of high-quality protein resources, exhibits favorable bio-compatibility, environmental stability and other beneficial biological values. Nevertheless, the inadequate exploitation and low-value applications have impeded its development in the food industry. Based on the excellent amphiphilic structure of it, Antarctic krill protein, is expected to become a new material for constructing nutrient delivery system. In this study, salt-soluble Antarctic krill protein was used as carrying material to facilitate the delivery of astaxanthin hydrophobic nutrient factors by ultrasonic crushing and self-assembly. The micro-structure, bio-compatibility and antioxidant properties of astaxanthin nanoparticles were characterized and analyzed, so as to expand the application of Antarctic krill protein toward the field of nutrient delivery. The results showed that the astaxanthin nanoparticles prepared on the basis of salt-soluble Antarctic krill protein were spherically distributed, with favorable water solubility and thermal resistance. Furthermore, astaxanthin nanoparticles could enhance the biocompatibility of astaxanthin, and exhibited superior performance to free astaxanthin in inhibiting H2O2-induced ROS up-regulation and mitochondrial membrane potential depolarization in GES-1 cells. From the perspective of efficiency and multiple utilization of Antarctic krill resources, this study has established an innovative application of salt-soluble krill protein as a new direction of delivery materials.

Influence of dietary resveratrol supplementation on integrity and colloidal characteristics of Myofibrillar proteins in broiler chicken breast meat

Abstracts This study was designed to elucidate the impact of dietary resveratrol (RES) supplementation on the free radical activity within the breast muscle of broiler chickens and to assess its effects on the structural and colloidal attributes of myofibrillar proteins (MPs). A total of 180 1-day-old male AA broiler chickens was divided to 2 groups (a CON group fed a control diet and a RES group fed the control diet supplemented with 400 mg/kg RES), each with 6 replicates and 15 chickens per replicate. The feeding test lasted for 6 weeks. The findings indicate that RES, recognized for its potent antioxidant properties, markedly diminished free radical activity, thereby curtailing the oxidative degradation of MPs and augmenting the integrity of their conformational structure. The intricate MP conformation is pivotal in dictating the functional attributes of the protein colloid. RES supplementation was observed to diminish the mobility of water molecules, thereby enhancing the stability of the colloidal system and improving the water-holding capacity and the visual appeal in terms of whiteness of colloid. Concurrently, the stabilization of the protein structure facilitated an increase in the intermolecular cohesive forces within the colloid, resulting in a denser and more stable microstructure, which significantly bolstered the mechanical strength of the colloid. In summary, the incorporation of RES as a dietary supplement in poultry feed presents a promising strategy to fortify the stabilization of proteins in chicken breast meat, offering a valuable alternative for the production of high-quality poultry meat products.

Binding and distribution regularity of water molecules in high-moisture textured Antarctic krill (Euphausia superba) meat

High-moisture extrusion technique with the advantage of high efficiency and low energy consumption is a promising strategy for processing Antarctic krill meat. Consequently, this study aimed to prepare high-moisture textured Antarctic krill meat (HMTAKM) with a rich fiber structure at different water contents (53 %, 57 %, and 61 %) and to reveal the binding and distribution regularity of water molecules, which is closely related to the fiber structure of HMTAKM and has been less studied. The hydrogen-bond network results indicated the presence of at least two or more types of water molecules with different hydrogen bonds. Increasing the water content of HMTAKM promoted the formation of hydrogen bonds between the water molecules and protein molecules, leading to the transition of the β-sheet to the α-helix. These findings offer a novel viable processing technique for Antarctic krill and a new understanding of the fiber formation of high-moisture textured proteins.

Physicochemical Properties and Metal Ion-Binding Capacity of Thermal-Induced Antarctic Krill Protein Aggregates under Different pH Conditions

Protein properties can be modified by thermal treatment at different pH values, resulting in the formation of protein aggregates with diverse morphologies and functionalities. This study investigated the morphology of aggregates of Antarctic krill protein (AKPS) formed by thermal treatment (90 °C, 15 min) at pH 2, 3, 4, and 6-12, characterized the different morphologies of AKPS, and determined the metal ion (Ca2+, Fe2+, and Zn2+)-binding capacities. Results showed that heat treatment with different pH values generated various AKPS with distinct morphology and metal ion-binding abilities. AKPS have formed fibrils at pH ≤ 3, particles at pH 4-7, and amorphous aggregates at pH ≥ 8. Fibrous AKPS (pH 2) exhibited a high solubility (80.36%) and strong reducing effect on iron. The binding capacities of Ca2+ and Fe2+ reached 36.08% and 66.75%. Particulate AKPS (pH 6 and 7) primarily only showed Zn2+-binding capacity similar to that of casein phosphopeptide (17.33%). Amorphous AKPS (pH 9-11) displayed the optimal capacity to bind Zn2+ and Fe2+ (26.90% and 74.94%). The alterations in morphology and functional characteristics of AKPS permit the design of various nanostructures for food-derived mineral supplements, thus developing their potential for application in functional foods.

Effects of different hydrocolloids on the 3D printing and thermal stability of chicken paste

This study investigated the effect of different hydrocolloids on the improvement of the printability and post-processing stability of minced chicken meat, each hydrocolloid was prepared with 1 % formulation and compared with the control. The effects of these hydrocolloids on the rheological properties of chicken mince and complex model printing capability were explored separately, while the cooking loss and microstructure changes of the samples before and after heating were analyzed. The results showed that the chicken mince gel containing carrageenan was more suitable for printing, increased the yield stress and apparent viscosity of the samples, and the printing process was easier to mold. In addition, carrageenan increased the hardness of the samples, and the microstructures were compact and changed little during the heating process, and the water was locked in the gel matrix, reducing shape changes during the heating process. The use of hydrocolloids improves the stability of post-processing of chicken 3D printing.

Characterization and in vitro calcium release of the novel calcium-loaded complexes using Antarctic krill protein and pectin: Effect of different blending sequences

Food-grade biopolymer-based complexes are of particular interest in the field of biologic ingredient delivery owing to unique controlled-release properties. Herein, three calcium-loaded complexes using Antarctic krill protein (P) and pectin (HMP) with different blending sequences were designed, named P + Ca + HMP, P + HMP + Ca and HMP + Ca + P, respectively. The calcium-loaded capacity, structural properties, and in vitro gastrointestinal calcium release of the complexes were investigated. The results demonstrated that the calcium binding rate and content of the P + Ca + HMP complex were the highest, reaching to 90.3 % and 39.0 mg/g, respectively. Particularly, the P + Ca + HMP complex exhibited a more stable fruit tree-like structure. Furthermore, the structural analysis confirmed that the primary interaction forces involved hydrogen bond, electrostatic, hydrophobic and ionic bond interaction. Ultimately, the P + Ca + HMP complex demonstrated superior calcium delivery. In conclusion, a novel calcium delivery system was successfully developed based on optimized the self-assembly sequence, which held significant importance in promoting the high-value utilization of Antarctic krill protein and enhancing the in vitro bioaccessibility of calcium.

3D printing of prawn mimics with faba proteins: The effects of transglutaminase and curdlan gum on texture

With its capability for automated production of high-resolution structures, 3D printing can develop plant-based seafood mimics with comparable protein content. However, the challenge lies in solidifying 3D printed products to achieve the firmness of seafood. Targeting prawn, texturisation of its 3D printed mimic by curdlan gum was compared against incubation with a protein cross-linking enzyme, microbial transglutaminase. Faba bean protein extract (FBP) was selected for its lightest colour. To confer structural stability to the FBP-based ink without hindering extrudability, adding 1 % xanthan gum was optimal. Printed curdlan-containing mimics were steamed for 9 min, while printed transglutaminase-containing mimics were incubated at 55 °C before steaming. Either adding 0.0625 % or 0.125 % w/w curdlan or, incubating the transglutaminase-containing mimics for an hour achieved chewiness of 818.8-940.6 g, comparable to that of steamed prawn (953.13 g). Curdlan hydrogel penetrated and reinforced the FBP network as observed under confocal imaging. Whereas incubation of transglutaminase-containing mimics enhanced microstructural connectivity, attributable to transglutaminase-catalysed isopeptide cross-linkages, and the consequent increase in disulfide bonding and β-sheet. Ultimately, transglutaminase treatment appeared more suitable than curdlan, as it yielded mimics with cutting strength comparable to steamed prawn. Both demonstrated promising potential to broaden the variety of 3D printed seafood mimics.

Gelation of crocodile myofibrillar protein - κ-carrageenan mixtures in two low-NaCl solution

Crocodile meat is a novel reptile meat source, but its processing method is rare. This study investigated the effect of κ-carrageenan addition and partial substitution of NaCl on the gel properties of crocodile myofibrillar protein (CMP). Result showed that CMP formed gel when temperature above 60 ℃. The water-holding capacity, gel strength, denaturation degree, sulfhydryl content covalent bond and hydrophobic bond of gel in KCl solution were significantly higher than those in CaCl2 solution (P < 0.05). K+ induced CMP to form a tight network structure with uniform small pores though covalent and hydrophobic bonds, but the gel properties were reduced by κ-carrageenan. In CaCl2 solution, κ-carrageenan improved the gel structure by filling the protein network through hydrogen bonding. Therefore, it can be concluded that KCl is better than CaCl2 in the manufacturing of low-sodium crocodile foods. Moreover, κ-carrageenan was only beneficial to gel quality in CaCl2 solution.

Comparison and analysis of mechanism of β-lactoglobulin self-assembled gel carriers formed by different gelation methods

Based on the findings of our previous studies, a comprehensive comparative investigation of the quality and formation mechanism of gels obtained from protein self-assemblies induced by different methods is necessary. Self-assembled heat-induced gels had higher gel mechanical strength, and hydrophobic interactions played a greater role. Whether or not heat treatment was used to induce gel formation may play a more important role than the effect of divalent cations on gel formation. Hydrogen bonds played an important role in all gels formed using different gelation methods. Furthermore, Self-assembled cold-induced gels were considered to can load bioactive substances with different hydrophilicity properties due to the high water-holding capacity and the smooth, dense microstructure. Therefore, β-lactoglobulin fibrous and worm-like self-assembled cold-induced gels as a delivery material for hydrophilic bioactive substances (epigallocatechin gallate, vitamin B2) and amphiphilic bioactive substance (naringenin), with good encapsulation efficiency (91.92 %, 97.08 %, 96.72 %, 96.52 %, 98.94 %, 97.41 %, respectively) and slow-release performance.

Elucidating the mechanisms of ultrasound treatment combined with κ-carrageenan addition enhancing the gelling properties of heat-induced myofibrillar protein gel

This work investigated the effect of ultrasound (US) treatment synergized with κ-carrageenan (KC) on the gel properties, structural characteristics and microstructures of myofibrillar protein (MP) gel. The results demonstrated that simply adding KC enhanced the gel strength and water holding capacity (WHC) of MP gels. Moreover, the gel strength and WHC of MP gels were increased by 56.67 % and 76.19 % via 20 min US treatment synergized with KC, which was mainly attributed to the changes in sulfhydryl content, surface hydrophobicity, and fluorescence intensity of MP gels. Based on the results of molecular docking and secondary structure, it can be hypothesized that the synergistic effect resulted in the rearrangement of the proteins, which altered the interaction site between MP gels and KC, accompanied by stronger binding. Furthermore, the microstructural results indicated that moderate US treatment (20 min) facilitated the production of a more compact and denser MP gels matrix with uniformly sized and distributed pores. However, excessive US treatment (40 and 50 min) caused the MP gels to form looser and disordered gel structure, which reduced the gel strength and WHC. This study suggested that combining of US and KC was a potential tactic to enhance the gelling properties of heat-induced MP gels.

Influence of dextrans on the textural, rheological, and microstructural properties of acid-induced faba bean protein gels

Dextrans (DXs) are a group of natural polysaccharides with different branching patterns. Previous studies examining the effects of DXs on plant protein gels have only focused on α-(1 → 3)-branched DXs. Here, we compared the effects of α-(1 → 3)-branched DX L12 with those of two α-(1 → 2)-branched DXs on the properties of glucono-δ-lactone-induced faba bean protein isolate (FPI) gels. DX L12 showed stronger effects in decreasing gel hardness and enhancing gel viscoelasticity than the other two DXs. Moreover, DX L12 decreased the water-holding capacity of FPI gels, whereas the other DXs enhanced it. Microstructural analysis revealed that DX addition promoted phase separation during gel formation. However, FPI/L12 gels exhibited greater phase separation than the other two gels and contained larger void spaces. These differences could be attributed to the varying water adsorption and self-association properties of the DXs. These findings could guide the application of DX in the tailored preparation of plant protein gels.

Rheology, physicochemical properties, and microstructure of fish gelatin emulsion gel modified by γ-polyglutamic acid

In this work, the effect of the addition of γ-polyglutamic acid (γ-PGA) on the rheology, physicochemical properties, and microstructure of fish gelatin (FG) emulsion gel was investigated. Samples of the emulsion gel were evaluated for rheological behavior and stability prior to gelation. The mechanical properties and water-holding capacity (WHC) of the emulsion were determined after gelation. The microstructure of the emulsion gel was further examined using confocal laser scanning microscopy (CLSM). The results indicated a gradual increase in the apparent viscosity and gelation temperature of the emulsion at a higher concentration of γ-PGA. Additionally, frequency scan results revealed that on the addition of γ-PGA, FG emulsion exhibited a stronger structure. The emulsion containing 0.1% γ-PGA exhibited higher stability than that of the control samples. The WHC and gel strength of the emulsion gel increased on increasing the γ-PGA concentration. CLSM images showed that the addition of γ-PGA modified the structure of the emulsion gel, and the droplets containing 0.1% γ-PGA were evenly distributed. Moreover, γ-PGA could regulate the droplet size of the FG emulsion and its size distribution. These findings suggest that the viscoelasticity and structure of FG emulsion gels could be regulated by adjusting the γ-PGA concentration. The γ-PGA-modified FG emulsion gel also exhibited improved rheology and physicochemical properties. The results showed that γ-PGA-modified FG emulsion gel may find potential applications in food, medicine, cosmetics, and other industries.

Promising effects of β-glucans on gelation in protein-based products: A review

Gel property is one of the most important abilities to endow protein-based food products with a unique texture and higher overall acceptability. Cereal β-glucan (BG) is widely applied in protein-based products to improve the stability of the protein gel by increasing water holding capacity, storage modulus (G'), loss modulus (G") and linking with protein through more exposed sites, making it easier to form a stronger three-dimensional gel network. In addition, BG may be cross-linked with proteins, or physically embedded and covered in protein network structures, interacting with proteins mainly through non-covalent bonds including hydrogen bonding and electrostatic interaction. Furthermore, the transition of the α-helix to the β-form in the protein secondary structure also contributes to the stability of the protein gel. The practical applications of BG from different cereals in protein-based products are summarized, and the rheological properties, microstructure of protein as well as the underlying interaction mechanisms between BG and protein are discussed. In conclusion, cereal BG is a promising polysaccharide in developing nutritional protein-based products with better sensory properties.

Elucidating the molecular mechanism of water migration in myosin gels of Nemipterus virgatus during low pressure coupled with heat treatment

The relationship between myosin denaturation, aggregation and water migration in Nemipterus virgatus myosin gels with different treatment processes under optimal low pressure coupled with heat treatment was investigated to clarify the molecular mechanism of water migration. With the different treatment processes, the proportion of bound water of the myosin gels increased significantly (P < 0.05). Denaturation of myosin S1 sub-fragments and α-helical unfolding during different treatment processes led to an increase in β-sheets content. These promote increased exposure of Try residues and hydrophobic groups of myosin, formation of clathrate hydrates, and reduced mobility of bound water. Furthermore, hydrophobic interactions and disulfide bonds caused the head-head and head-hinge to coalesce into a 3D honeycomb network with greater fractal dimension, less lacunarity, smaller water hole diameter and more water holes. This increased the capillary pressure experienced by the bound water, causing immobile water to migrate towards the bound water. The present study may be necessary to improve the mechanism of water migration in protein gel systems and to promote the industrial application of high pressure processing technology in surimi-based foods.

Effect of к-carrageenan on saltiness perception and texture characteristic related to salt release in low-salt surimi

The purpose of this study was to investigate the effect of Kappa (к)-carrageenan on texture and perception of saltiness of low salt surimi. The low-field nuclear magnetic resonance (LF-NMR) and microstructure results showed that к-carrageenan could promote the formation of more immobilized water in low salt surimi gel, change its matrix structure, and lead to the uneven spatial distribution of sodium, thus enhancing saltiness perception. The rheological properties of surimi showed that к-carrageenan could increase the network strength of low salt surimi gel and improve its thermostability. Furthermore, the low salt surimi gel added with к-carrageenan has lower cooking loss, higher water holding capacity (WHC), gel strength and improved texture properties. Therefore, к-carrageenan has the effects of improving the quality and increasing salt perception of surimi gel. This study provides a new method for reducing salt consumption in food industry.

Effects of blackberry (Rubus spp.) polysaccharide on the structure and thermal behavior of the myofibrillar protein of chicken breast meat

Blackberry crude polysaccharides (BCP) was added to chicken breast to inspect the intermolecular interaction with myofibrillar protein (MP). The influence of BCP on the thermal transformation behavior and protein micro-structure during temperature rise period was studied. The results showed that the interaction between BCP and MP was mainly affected by the concentration of BCP and heating temperature. The results of infrared spectrophotometer and nano-particle/zeta potentiometer showed that a BCP-MP complex was generated through hydrogen bond and electrostatic interaction, which could promote the transformation of MP from β-folding to β-Angle transformation. The fluorescence spectra showed that the BCP was helped to the spread of protein structure of the MP. Moreover, synchronous thermal analyzer and rheometer results revealed that the BCP increased the enthalpy value and elastic modulus of MP. Scanning electron microscope verified pores inside the BCP-MP complex are more evenly distributed and smaller, which led to the high cross-linking of network and good stability of water distribution for the MP. The addition of BCP enhances the hydrogen bonds and disulfide bonds of MP molecules, which can strengthen the network structure and ultimately improve the performance of meat products.

Functional, physicochemical, and structural properties of the hydrolysates derived from the abalone (Haliotis discus subsp hannai Ino) foot muscle proteins

This study was conducted to investigate functional, physicochemical, and structural properties of abalone foot muscle proteins (AFPs) and their hydrolysates (HAFPs) obtained using animal protease (HA), papain (HPP), and Protamex® (HP) at different time points. The HA-hydrolysate obtained after 0.5 h of treatment demonstrated the highest solubility at pH 7.0 (84.19%); the HPP-hydrolysate at 4 h exhibited the highest degree of hydrolysis (11.4%); the HPP-hydrolysate at 0.5 h had the highest oil holding capacity (2.62 g/g) and emulsion stability index (39.73 min), and the HP-hydrolysate at 4 h had the highest emulsifying activity index (93.23 m2/g) and foaming stability (91.45%); Regarding the physicochemical properties, the HPP-hydrolysates revealed the largest particle size, higher absolute zeta potential, and superior interfacial activity. Structural characterization demonstrated the enzymolysis-based changes in the composition and the secondary structure of the AFPs. These results provide practical support for the theoretical basis of the use of AFPs as a source of nutritive proteins in the food industry.

Effects of hydrocolloids as fat-replacers on the physicochemical and structural properties of salt-soluble protein isolated from water-boiled pork meatballs

Konjac glucomannan (KGM), xanthan gum (XG), guar gum (GG), and κ-carrageenan (KC), as substituent, are commonly used in ground pork products. Here, the content of these (0.5, 1.0, 1.5, and 2.0%, w/w) on the gel properties, thermal properties, and interaction forces of salt-soluble protein (SSP) isolated from water-boiled pork meatballs were investigated. We found 1.0% KGM, 0.5% XG, 0.5-2.0% GG, and 0.5-2.0% KC to water-boiled pork meatballs exerted a positive effect on the denaturation temperature, hydrogen bonds, hydrophobic interactions, disulfide bonds, α-helix, and β-sheet content of SSP, as well as the strength and storage modulus of the modified protein gel. The addition of these hydrocolloids with the addition of 1.0% aggregated myosin and actin, led to the enhancement of the bands corresponding to myosin heavy chain and actin. The prediction model of gel strength showed that the gel strength was negatively correlated with Tpeak1, Tpeak2, and ionic bond. This study provides theoretical guidance for improving the application of hydrocolloids in pork-based foods.

Discovery of Potential Protein Markers Associated with Quality Characteristics of Antarctic Krill (Euphausia superba) Surimi Gel

Antarctic krill are a consumption resource with great exploitation potential. However, the poor gel properties of Antarctic krill meat seriously limit its high-value application. In the present study, the quality characteristics and proteome changes of the κ-/ι-carrageenan-Antarctic krill surimi gel were systematically analyzed and compared. In addition, the transcriptome sequencing of Antarctic krill was carried out, which filled the gap in the Antarctic krill database. Higher molecular forces (disulfide bond and hydrophobic interaction) and the degree of network cross-linking significantly promoted the formation of κ/ι-carrageenan-Antarctic krill surimi compared to that of Antarctic krill surimi. This is the first study to investigate and map potential protein markers for quality characteristics of Antarctic krill surimi based on mass spectrometry-based label-free quantitative proteomics. The results could provide a theoretical reference for the quality control of Antarctic krill during application.

Mechanism for improving the gel properties of transglutaminase-mediated porcine myofibrillar protein by ultrasonic pretreatment combined with carrageenan

To improve the limitation of transglutaminase on the quality of myofibrillar protein (MP) gel, this study investigated the synergistic effect of ultrasonic pretreatment in combination with carrageenan on the gel properties of transglutaminase-mediated MP gels. The synergistic effect generated gel with lower surface hydrophobicity and fluorescence intensity. Combined with the secondary structure results, it can be hypothesized that the synergistic effect caused the rearrangement of the proteins and the formation of aggregates wrapping hydrophobic groups, which changed the structure and phase behavior of the proteins. The synergistic effect also improved the formation of dense and interpenetrating gel networks, which reduced cooking loss and produced composite MP gels with optimal gel strength. Moreover, FTIR spectroscopy revealed the presence of electrostatic interactions in the hybrid gel system. This study provides a theoretical basis and experimental foundation for the effective use of high-tech composite functional components to improve the quality of gel products.

Effects of κ-carrageenan gum on 3D printability and rheological properties of pork pastes

The effects of κ-carrageenan gum (KG) on the 3D printability and rheological properties of pork pastes were investigated in this study. There were five groups with different levels of KG (0, 2, 4, 6, and 8 g/kg) named as KG-0, KG-2, KG-4, KG-6, and KG-8, respectively. The addition of KG increased the yield stress, viscosity, shear stress, recovery percentage, storage modulus, loss modulus, and initial and average flow forces (P < 0.05). The results of low-field nuclear magnetic resonance analysis revealed that addition of KG reduced T₂₁ and T₂₂ (P < 0.05). The best printing parameters were obtained by accuracy and stability results: printing filling percent, 90%; printing speed, 35 mm⋅s^-1; layer height, 2 mm; nozzle diameter, 1.55 mm, and KG addition level, 6 g/kg. KG addition improved the hardness, springiness, chewiness, cohesiveness, adhesiveness, and density, respectively (P < 0.05). The results suggested that KG addition improved the rheological properties and 3D printability of the pork pastes.

Contribution of κ-/ι-carrageenan on the gelling properties of shrimp myofibrillar protein and their interaction mechanism exploration

BACKGROUND

The contribution and mechanism of κ-/ι-carrageenan (CG) with different hydration characteristics on the gelling properties of shrimp myofibrillar protein (MP) gelation was studied.

RESULTS

The gel strength, water-holding capacity and viscoelastic properties of MP gels were significantly enhanced by 1.0% κ-/ι-CG (P < 0.05), but the microstructure showed that excessive carrageenan caused fragmentation of the gel network and a corresponding decrease in gel properties. Compared to MP-ιCG, MP-κCG showed larger breaking force and shorter breaking distance, thus enhancing the hardness and brittleness of the gel, which might be ascribed to a reinforced network skeleton and a tighter binding of κCG-myosin. However, MP-ιCG stabilized more moisture in the gel network, thereby improving the tenderness of the gel, which might be related to the electrostatic repulsion observed between the sulfate groups of ιCG and the myosin observed by molecular docking. In addition, the β-sheet content and intermolecular interactions might be positively correlated with gel properties.

CONCLUSION

In this study, a composite gel system was constructed based on the interaction of MP and CG. The quality differences of two kinds of CG-MP gels were clarified, which will provide guidance for the application of different kinds of carrageenan and the development of recombinant meat products with specific quality. © 2022 Society of Chemical Industry.

Effects of partial replacement of unwashed Antarctic krill surimi by Litopenaeus vannamei surimi on the heat-induced gelling and three-dimensional-printing properties

There is an emerging consumption of the Antarctic krill (AK) muscle-based food due to its excellent nutritional value and enormous biomass storage capacity. However, the coarse texture of the muscle and the weak gelling properties of AK protein impede its expansion in surimi-based products. This investigation successfully prepared heat-induced gels of AK surimi with desirable textural properties by including Litopenaeus vannamei in varying proportions. Higher concentrations of L. vannamei resulted in improved three-dimensional printability, greater water-holding capacity (WHC), larger viscoelastic modulus, and a well-formed microstructural matrix of AK surimi, due to an increased level of myofibrillar protein. Compared with AK, L. vannamei muscle had double the salt-soluble protein content, which was corroborated by increased intensity of bands of actin, paramyosin, tropomyosin, and myosin light chains on reducing SDS-PAGE. DSC results indicated that a high ratio of L. vannamei elevated the denaturation temperature and enthalpy of myosin, sarcoplasmic protein, and actin, suggesting a high degree of cross-linking. It was also found that when hydroxypropyl cassava starch was added at 0.5% (w/w), WHC and gel strength were further improved with a more compact gel matrix. The successful preparation of unwashed mixed surimi with AK meat fully exploited in this study provides an option for AK surimi-based product industrialization.

Interaction between Kidney-Bean Polysaccharides and Duck Myofibrillar Protein as Affected by Ultrasonication: Effects on Gel Properties and Structure

The interaction of polysaccharides-protein with varied origins and structures provides opportunities for tailoring the physicochemical qualities of food protein-based materials. This work examined the feasibility of ultrasound-modified interaction between kidney bean dietary fiber (KSDF) and duck myofibrillar proteins (MP) to improve the physicochemical properties of the gel matrices. Accordingly, gel strength, water holding capacity, solubility, chemical interaction, secondary structure, and network structure of MP were determined. The addition of KSDF combined with the ultrasound treatment contributed to the improved water retention capability, G' values, and the reduced particle size of protein molecules, corresponding with the formation of dense pore-like structures. The results demonstrated that 1% KSDF and ultrasonication at 400 W significantly enhanced gel strength by up to 109.58% and the solubility increased by 213.42%. The proportion of α-helices of MP gels treated with 1% KSDF and ultrasonication at 400 W was significantly increased. The sonication-mediated KSDF-MP interaction significantly improved hydrophobic interactions of the proteins, thus explaining the denser network structure of the MP gels incorporated KSDF with ultrasound treatments. These results demonstrated the role of ultrasonication treatments in modifying KSDF-protein interaction to improve the gel and structural properties of the MP gels.

Effects of κ-carrageenan of gel quality on threadfin bream (Nemipterus spp.) surimi containing salted duck egg white powder

This study aimed to evaluate the combined effect of κ-carrageenan and salted duck egg white powder (SDEWP) in improving the gel quality of threadfin bream surimi. Effects of κ-carrageenan at different levels (0-2 %) on gel properties of threadfin bream surimi without and with salted duck egg white powder at 3 % (protein equivalent) were investigated. A combination of 0.5 % κ-carrageenan and SDEWP increased breaking force of surimi gel by 139.7 % and deformation by 55.1 %, compared to the control (P < 0.05). The expressible moisture content (EMC) was decreased by 50.0 % in the surimi gel added with 0.5 % κ-carrageenan and SDEWP. Hardness, cohesiveness, gumminess, and chewiness of surimi gel were also improved (P < 0.05). However, springiness of surimi gel was not affected. SDEWP reduced proteolytic degradation in surimi gel. Surimi gel with augmented whiteness was attained when κ-carrageenan was added at higher levels. Microstructure of surimi gel shown that the gel became denser and more uniform when added with 0.5 % κ-carrageenan and SDEWP. Therefore, κ-carrageenan can be used to enhance the effectiveness of SDEWP and further improve the gel quality of threadfin bream surimi added with SDEWP.

Insight into the Gel Properties of Antarctic Krill and Pacific White Shrimp Surimi Gels and the Feasibility of Polysaccharides as Texture Enhancers of Antarctic Krill Surimi Gels

Antarctic krill is a potential and attractive resource for consumption. However, most Antarctic krill meat is used to produce primary products with low commercial value, with few highly processed products. This study aimed to evaluate and improve the gelling properties of Antarctic krill surimi, with Pacific white shrimp surimi as control. Compared with Pacific white shrimp surimi, the lower β-sheet content and protein aggregation degree had a severe impact on the formation of the gel network of Antarctic krill surimi, which resulted in weaker breaking force, gel strength, and viscoelasticity (p < 0.05). Moreover, water retention capacity and molecular forces had a positive effect on the stability of the gel matrix of shrimp surimi. Thus, the high α-helix/β-sheet ratio, weak intermolecular interactions, and low level of protein network cross-linkage were the main reasons for the poor quality of Antarctic krill surimi. On this basis, the effects of six polysaccharides on the texture properties of Antarctic krill surimi were studied. Chitosan, konjac glucomannan, sodium carboxyl methyl cellulose, and waxy maize starch resulted in no significant improvement in the texture properties of Antarctic krill surimi (p > 0.05). However, the addition of ι-carrageenan (2%) or κ-carrageenan (1~2%) is an effective way to improve the texture properties of Antarctic krill surimi (p < 0.05). These findings will contribute to the development of reconstituted Antarctic krill surimi products with high nutritional quality and the promotion of deep-processing products of Antarctic krill meat.

Effect of κ-carrageenan on the gelation properties of oyster protein

Proteins and polysaccharides commonly coexist in the food system, forming complexes and coacervates to make tailor-made food. In this study, the effects of κ-carrageenan on the rheological behavior, network structure, textures, and molecular force of oyster protein (OP treated with high-pressure homogenization were investigated. Rheological results showed that κ-carrageenan improved the storage modulus of OP, and the higher concentration of κ-carrageenan accelerated the gelation of OP. The second derivative of infrared spectroscopy revealed that κ-carrageenan contributed to the formation of β-sheet in OP. Molecular force and texture analysis showed that κ-carrageenan might promote the increase of hydrophobic bonds and disulfide bonds, which was helpful to enhance gel strength. The microstructure showed that the OP gel with 1.5% κ-carrageenan had a compact network structure with abundant minor mesh and sheet edge. This study reveals the gelation mechanism of OP/κ-carrageenan and provides the theoretical basis for developing innovative oyster products.

Complex characterization and formation mechanism of scallop (Patinopecten yessoensis) protein hydrolysates/κ-carrageenan/konjac gum composite gels

The combination of κ-Carrageenan (KC) and konjac gum (KGM) were introduced to examine the impact on gelation and microstructural behaviors of scallop male gonads hydrolysates (SMGHs) and the involvement of intermolecular forces. In terms of G' response of SMGHs/KGM/KC, it obviously enhanced by 3.6- and 108.5-fold than controls of KGM/KC and SMGHs/KC at 0.1 Hz, accompanying increasing melting temperatures from 27.9 (KGM/KC) and 30.0 (SMGHs/KC) to 33.7°C (SMGHs/KGM/KC), respectively. Additionally, SMGHs/KGM/KC with decreasing relaxation time T₂₃ and blue shift of hydroxyl group than controls suggested higher water retention capacity and ordered conformation. Moreover, SMGHs/KGM/KC formed compact networks with thick walls as reflected by cryo-SEM and showed rougher surface with more aggregation as reflected by AFM. Furthermore, electrostatic in couple with hydrophobic interactions were dominant interactions, while hydrogen bonds were involved in subordinately in SMGHs/KGM/KC. PRACTICAL APPLICATION: Scallop (Patinopecten yessoensis) male gonads are always discarded during processing despite high-protein content and edibility. In the current research, scallop male gonad hydrolysates (SMGHs) exhibited gelation behavior, which have a potential role in developing marine source protein as a functional food base such as kamaboko gels, can, sausage and spread and even delivery vehicles for bioactive compounds.

Interaction-Induced Structural Transformations in Polysaccharide and Protein-Polysaccharide Gels as Functional Basis for Novel Soft-Matter: A Case of Carrageenans

Biocompatible, nontoxic, and biodegradable polysaccharides are considered as a promising base for bio-inspired materials, applicable as scaffolds in regenerative medicine, coatings in drug delivery systems, etc. The tunable macroscopic properties of gels should meet case-dependent requirements. The admixture of proteins to polysaccharides and their coupling in more sophisticated structures opens an avenue for gel property tuning via physical cross-linking of components and the modification of gel network structure. In this review recent success in the conformational studies of binary protein-polysaccharide gels is summarized with the main focus upon carrageenans. Future perspectives and challenges in rational design of novel polysaccharide-based materials are outlined.

Preparation, Characterization, and Mechanism of Antifreeze Peptides from Defatted Antarctic Krill (Euphausia superba) on Lactobacillus rhamnosus

Defatted Antarctic krill powder is the main by-product in the manufacturing of krill oil. Exploring a high value-added approach for utilizing this protein-rich material has received much attention in research and industry. Given this, the preparation and primary characterization of antifreeze peptides from defatted Antarctic krill (AKAPs) were carried out in this study. The cryoprotective effect of AKAPs on Lactobacillus rhamnosus ATCC7469 was also investigated. The results showed that Protamex was the optimum protease for AKAP preparation from defatted Antarctic krill. AKAPs were found to be rich in short peptides, with the MW ranging from 600 to 2000 Da (69.2%). An amino acid composition analysis showed that AKAPs were rich in glutamic acid (18.71%), aspartic acid (12.19%), leucine (7.87%), and lysine (7.61%). After freezing, the relative survival rate of Lactobacillus rhamnosus in the 1.0 mg/mL AKAP-treated group (96.83%) was significantly higher than in the saline group (24.12%) (p < 0.05). AKAPs also retarded the loss of acidifying activity of L. rhamnosus after freezing. AKAPs showed even better cryoprotective activity than three commercial cryoprotectants (sucrose, skim milk, and glycerol). In addition, AKAPs significantly alleviated the decrease in β-galactosidase and lactic dehydrogenase activities of L. rhamnosus (p < 0.05). Furthermore, AKAPs effectively protected the integrity of L. rhamnosus cell membranes from freezing damage and alleviated the leakage of intracellular substances. These findings demonstrate that AKAPs can be a potential cryoprotectant for preserving L. rhamnosus, providing a new way to use defatted Antarctic krill.

Effect of NaCl on the Rheological, Structural, and Gelling Properties of Walnut Protein Isolate-κ-Carrageenan Composite Gels

In this study, we discovered that a certain concentration of Na⁺ (15 mM) significantly improved the bond strength (12.94 ± 0.93 MPa), thermal stability (72.68 °C), rheological properties, and textural attributes of walnut protein isolate (WNPI)-κ-carrageenan (KC) composite gel. Electrostatic force, hydrophobic interaction, hydrogen bond, and disulfide bond were also significantly strengthened; the α-helix decreased, and the β-sheet increased in the secondary structure, indicating that the protein molecules in the gel system aggregated in an orderly manner, which led to a much denser and more uniform gel network as well as improved water-holding capacity. In this experimental research, we developed a new type of walnut protein gel that could provide technical support for the high-value utilization and quality control of walnut protein.

Effects of κ-Carrageenan and Guar Gum on the Rheological Properties and Microstructure of Phycocyanin Gel

The effects of two polysaccharides on the performance and microstructure of phycocyanin gels were studied by choosing anionic polysaccharides (κ-carrageenan) and neutral polysaccharides (guar gum). The linear and nonlinear rheological properties and microstructure of the phycocyanin-polysaccharide composite gel were evaluated. The results show that both κ-carrageenan and guar gum can enhance the network structure of phycocyanin gel and weaken the frequency dependence. The sample with 0.4% κ-carrageenan has the highest gel strength. All samples exhibited Type I behavior (inter-cycling strain-thinning) and mainly elastic behavior. As the concentration of κ-carrageenan increases, hydrophobic interactions and disulfide bonds play an essential role in maintaining the three-dimensional structure of the gel. Too high a concentration of guar gum hinders the formation of protein disulfide bonds. This research can provide a theoretical basis for designing and developing new food products based on phycocyanin and different polysaccharides with ideal texture in the food industry.