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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. [ABSTRACT FROM AUTHOR]

The complex coacervation between scallop (Patinopecten yessoensis) female gonad protein isolates (SFGPIs) and sodium alginate (SA) was determined by the turbidimetric method. The impact of pH, total biopolymer concentration, biopolymer blend ratio, and various salt ionic on the mechanisms governing the complex coacervation of SFGPIs–SA complexes were also investigated. For the SFGPIs:SA ratio of 2:1 without adding NaCl, insoluble and soluble complexes were observed at pH 5.8 (pHφ1) and pH 8.2 (pHc) with the optimum biopolymer interactions appearing at pH 2.6 (pHopt). The maximum turbidity value increased with the increment of the total biopolymer concentration from 0.37 to 1.83 until attaining the critical value (0.75%). As the blend ratios rose from 1:3 to 12:1, the critical pH values (pHc, pHφ1, and pHopt) moved to higher pH. Furthermore, the addition of NaCl led to a remarkable decrease in turbidity over the whole pH region in SFGPIs–SA complexes. Moreover, monovalent ions (Na+ and K+) had the same effect on the formation of the SFGPIs–SA complex, whereas the divalent cations (Mg2+ and Ca2+) lessened the complex formation in comparison with the monovalent ions. This study offers a methodological and theoretical basis for the design of complex SFGPIs–SA systems by understanding the complex coacervation under different conditions. Practical Application: In recent years, several protein–polysaccharides complexes have been widely applied in food and biological systems. Scallop (Patinopecten yessoensis) female gonads are deemed as good marine sources for developing protein matrices on account of their high protein content and nutrients. In our study, the effects of different conditions on the mechanisms governing the complex coacervation of SFGPI–SA mixtures were investigated, and the instability of the system could be overcome by understanding the conditions for SFGPIs/SA complex formation, which have a feasible role in developing marine source‐protein as a functional food base such as kamaboko gels, can, sausage, fat substitutes, and delivery vehicles for bioactive compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • -KC hydrogel beads with more SMGHs can increase Cur load due to tight cross-linking. • -Modified FTIR and amorphous structure in SMGHs/KC/KCl prove successful Cur embedment. • -SMGHs/KC/KCl-Cur hydrogel beads have heterogeneous networks with backbone and voids. • -SMGHs/KC/KCl hydrogel beads perform as effective colon-targeting Cur delivery system. • -SMGHs/KC/KCl hydrogel beads promise Cur preservation above 90% during 30 day at 4 °C. Scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs)/ κ -carrageenan (KC)/KCl beads with SMGHs:KC ratios (0:10–5:5) were investigated. SMGHs/KC/KCl-Cur bead (5:5) exhibited the most intact spherical morphology and highest Cur loading content of 0.063 mg/0.1 g bead, ascribing to a shortened T 23 from 1607.9 to 966.4 ms, and red and blueshifts of O H, NH, amide I and II bands. The undetected fingerprint region within 7.82°-28.90° of SMGHs/KC/KCl-Cur beads indicated successful Cur entrapment. Moreover, SMGHs/KC/KCl-Cur beads exhibited shrinkage network backbones and larger void pores as SMGHs increased, with vessel percentage area, total number of junctions, total vessel length decreasing from 52.1, 1446.8, 57931.4 to 39.7, 530.5, 34458.4, and lacunarity increasing from 0.048 to 0.111, respectively. Furthermore, Cur showed approximately 50% release contents in colon phase and above 90% retention rate during 30 days of storage at 4 °C. These results suggested that SMGHs/KC/KCl-Cur beads exhibited sustained-release of Cur and promised stable Cur preservation. [ABSTRACT FROM AUTHOR]

This study evaluated the gel and microstructure properties of scallop (Patinopecten yessoensis) male gonads hydrolysates (SMGHs) combined with xanthan gum (XG). SMGHs/XG hydrogel matrix properties and structures were elucidated via different analysis tools such as rheometry, LF‐NMR, FTIR, AFM, and Cryo‐SEM. The addition of XG significantly improved the rheological properties of SMGHs, as indicated by 3.1‐fold G′ and 1.3‐fold melting temperature with increasing the XG dose to 5.6 mg/ml. The corresponding decrease in the T23 relaxation time from 450.3 to 365.6 ms also signified the strong binding between SMGHs and XG. SMGHs/XG also had a higher proton density (T1 and T2 weighted images) due to the higher bound and free water content of the hybrid gel systems, respectively. Additionally, the blueshift in the amide I and II bands in SMGHs/XG further indicated stronger electrostatic interactions between SMGHs and XG. Such scenarios resulted in a well‐distributed and compact network with a rougher surface of SMGHs/XG in comparison to pure SMGHs and XG, as assessed by AFM and SEM. These results suggest that SMGHs/XG gel could be a potential hybrid gel applied in the food industry. Practical Application: Scallop (Patinopecten yessoensis) male gonads are edible, but are usually discarded during processing of scallop adductor. Because of its rich nutrition and gelation properties, scallop male gonads have a potential role in developing marine source‐protein as a functional food base. The SMGHs/XG binary gel would be potentially applied in delivery system in food and biological fields. Further study is undergoing to apply SMGHs/XG binary gel to embed bioactive compounds, such as curcumin and β‐carotene. [ABSTRACT FROM AUTHOR]

Various bond disrupting agents including NaCl, GuHCl, urea, and SDS were introduced to investigate the intermolecular interactions between scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and κ‐carrageenan (κ‐C), which were monitored by changes in rheological property, water distribution, conformation characterization and microstructure by using rheometer, low field‐NMR relaxometry, Fourier transform infrared (FTIR) spectroscopy, cryo‐scanning electron microscopy (cryo‐SEM), and confocal laser scanning microscopy. The results showed that the bond disrupting agents deteriorated the rheological property of SMGHs/κ‐C in a dose‐dependent manner. Indeed, at the same concentration of 2 M, NaCl deteriorated the SMGHs/κ‐C more obviously than GuHCl and urea. In addition, SMGHs/κ‐C with bond disrupting agents possessed higher relaxation times including T21 and T23, indicating the migration to free water direction of bound and free water. Moreover, the FITR results showed the red‐shift in water regions (amide A and B bands), amide I and II bands, and indicated the breakdown of hydrogen bonds and electrostatic interactions, indicating a disordered structure in SMGHs/κ‐C by various bond disrupting agents. Furthermore, cryo‐SEM results showed the change of SMGHs/κ‐C from a homogeneous network to a looser and ruptured one with larger void spaces, and indicated the disrupted and tattered microstructure of SMGHs/κ‐C by various bond disrupting agents. Additionally, SMGHs/κ‐C as well showed less aggregates stained by RITC by bond disrupting agents. These results suggest that electrostatic interactions would be mainly involved in the maintenance of SMGHs/κ‐C gel network. This study could provide theoretical and methodological basis for hydrogel products with modified gel strength and microstructure by understanding the intermolecular interactions in gel system. Practical Application: Scallop (Patinopecten yessoensis) male gonads as a high‐protein part of scallop, is usually discarded during processing despite its edibility. In recent years, scallop male gonads are regarded as good sources to develop protein matrices due to their high protein content and numerous nutrients. In this study, scallop male gonad hydrolysates (SMGHs) were obtained by trypsin‐treated process. The considerable gelation behavior of SMGHs indicated that the SMGHs could be potentially utilized as a novel thickener and additive in production of kamaboko gels, can, sausage and spread with marine flavor. [ABSTRACT FROM AUTHOR]

Studying the noncovalent interactions between proteins and polysaccharides is quite important mainly due to the wide number of applications such as developing pH-responsive complexes. Scallop Patinopecten yessoensis male gonad hydrolysates‑sodium alginate (SMGHs-SA) was investigated as noncovalent complexes at pH from 1 to 10. The critical pH values pH C (around 6) and pHφ (around 4) were independent of the SMGHs-SA ratio, indicating the formation of soluble and insoluble complexes. The pH response of SMGHs-SA complexes was evaluated by investigating the rheological behavior, moisture distribution, functional group change and microstructure. Compared to the co-soluble and soluble complexes phases, the SMGHs-SA complexes had a higher storage modulus and viscosity as well as a lower relaxation time (T 23) in the insoluble complexes phase (pHφ>3). Additionally, the amide I band and COO− stretching vibration peaks were redshifted and the amide A band vibration peaks were blueshifted by acidification. Electrostatic interactions and intermolecular/intramolecular hydrogen bonding led to SMGHs-SA agglomeration at pH 3, forming a uniform and dense gel network structure with strong gel strength and water-retention capacity. This study provides a theoretical and methodological basis for the design of novel pH-responsive complexes by studying SMGHs-SA complex coacervation. • Scallop gonad hydrolysates (SMGHs) and sodium alginate (SA) could coacervate. • Acidification promoted the formation of SMGHs-SA coacervations. • Electrostatic interactions were the main force for the SMGHs-SA complex at pH 3. • Hydrogen bonding also drove the interaction of SMGHs and SA. [ABSTRACT FROM AUTHOR]

Studying the noncovalent interactions between proteins and polysaccharides is quite important mainly due to the wide number of applications such as developing pH-responsive complexes. Scallop Patinopecten yessoensis male gonad hydrolysates‑sodium alginate (SMGHs-SA) was investigated as noncovalent complexes at pH from 1 to 10. The critical pH values pH C (around 6) and pHφ (around 4) were independent of the SMGHs-SA ratio, indicating the formation of soluble and insoluble complexes. The pH response of SMGHs-SA complexes was evaluated by investigating the rheological behavior, moisture distribution, functional group change and microstructure. Compared to the co-soluble and soluble complexes phases, the SMGHs-SA complexes had a higher storage modulus and viscosity as well as a lower relaxation time (T 23) in the insoluble complexes phase (pHφ>3). Additionally, the amide I band and COO− stretching vibration peaks were redshifted and the amide A band vibration peaks were blueshifted by acidification. Electrostatic interactions and intermolecular/intramolecular hydrogen bonding led to SMGHs-SA agglomeration at pH 3, forming a uniform and dense gel network structure with strong gel strength and water-retention capacity. This study provides a theoretical and methodological basis for the design of novel pH-responsive complexes by studying SMGHs-SA complex coacervation. • Scallop gonad hydrolysates (SMGHs) and sodium alginate (SA) could coacervate. • Acidification promoted the formation of SMGHs-SA coacervations. • Electrostatic interactions were the main force for the SMGHs-SA complex at pH 3. • Hydrogen bonding also drove the interaction of SMGHs and SA. [ABSTRACT FROM AUTHOR]

Chia seed gum was extracted using high-speed shearing technology and further purified via ethanol precipitation. The composition, structural and rheological properties of crude chia seed gum (CCSG) and purified chia seed gum (PCSG) were evaluated and further compared with twelve commercial polysaccharides (agar, xanthan gum, κ-/ι-/λ-carrageenan, guar gum, carboxymethyl cellulose, locust bean gum, pectin, acacia gum, sodium alginate and konjac gum). The extraction yields of CCSG were significantly improved from 1.80% to 6.25% by high-speed shearing for 2.0 min. Compared to CCSG (36.63% and 3.985 × 105 g/mol), PCSG had a higher total neutral sugar content (51.85%), lower molecular weight (1.718 × 105 g/mol) and looser surface morphology. Furthermore, PCSG and CCSG had different monosaccharide composition. However, both CCSG and PCSG exhibited pseudoplastic fluid behavior, but PCSG had higher viscosity and modulus values than CCSG at the same concentrations. Compared to commercial polysaccharides, PCSG had rheological characteristics similar to those of xanthan gum, with high viscoelasticity and good stability against temperature change. The relaxation time T 2 curves showed that CCSG and PCSG had better water-holding capacity than most commercial polysaccharides. This study provided theoretical guidance for the potential utilization of chia seed gum as a thickening and stabilizing agent in the food industry. [Display omitted] • High-speed shearing can be applied for the extraction of chia seed gum. • Ethanol precipitation affects the physicochemical properties of chia seed gum. • PCSG shows higher viscosity, viscoelasticity and water-holding capacity than CCSG. • PCSG has similar or better functional properties than commercial polysaccharides. • Chia seed gum can be used as a novel source of plant polysaccharides. [ABSTRACT FROM AUTHOR]

Roes are the main byproducts during the processing of large yellow croaker (Pseudosciaena crocea) and have not been well utilized. Heat-induced gels were prepared by using P. crocea roe protein isolates (pcRPI), and the influence of pH on the gel properties was also investigated. pcRPI could not form a gel at pH 4–6 but showed gelation behaviors at pH 7–9. The pcRPI gels prepared at pH 8 had a lower gel point (84 °C), and their G ′ reached 535.4 Pa. Moreover, pcRPI gels formed at pH 8–9 had a more continuous network structure with a shorter T 2 relaxation time than those at other pH conditions. Additionally, vitellogenin and vitellogenin B and C in pcRPI easily formed protein complexes during heating. The hydrophobic interactions, which were the main force between protein molecules during heating, as shown by molecular dynamics simulation, also contributed to gel formation. pcRPI has the potential to be used as a novel hydrogel product in food and other fields. • The optimum pH of P. crocea roe protein isolates (pcRPI) to form gels was pH 8. • The water holding ability of pcRPI gels was enhanced as pH increased. • The pcRPI gels had smoother surface and continuous network structure at pH 8–9. • Hydrophobic interactions were the main forces in the formation of pcRPI gels. [ABSTRACT FROM AUTHOR]

Sea urchin Mesocentrotus nudus, Glyptocidaris crenularis, and Strongylocentrotus intermedius gonad protein isolates (mnGPIs, gcGPIs, and siGPIs) were extracted by isoelectric solubilization/precipitation (ISP) from the defatted gonads, and their functional properties were compared. Sodium dodecyl sulfate polyacrylamide gel electrophoresis results showed the similar protein pattern between each protein isolate and defatted gonad, indicating the high efficiency of ISP processing for protein recovery. Amino acid profileconfirmed that the mnGPIs and siGPIs could be potential sources of essential amino acid in nature. As regard to functional properties, mnGPIs showed higher water‐ and oil‐ holding capacities followed bysiGPIs and gcGPIs and all protein isolates presented great foaming property. As for emulsifying activity index (EAI), mnGPIs, gcGPIs, and siGPIs showed the minimum solubility and EAI at pH 5, 3, and 4, respectively, and behaved a pH‐dependent manner. The gcGPIs revealed the highest EAI from pH 6 to 8 among the samples. In addition, circular dichroism showed increased content of β‐sheet at the expense of α‐helix and β‐turn, suggesting the structure denaturation of the protein isolates. Indeed, no statistical difference was observed between secondary structure of mnGPIs and siGPIs. Moreover, ISP processing increased free sulfhydryl content of sea urchin protein isolates, but no difference was observed among the samples. Furthermore, siGPIs revealed the highest amount of total sulfhydryl and disulfide bonds, whereas both defatted gonads and protein isolates from G. crenularis presented the maximum surface hydrophobicity. These results suggest that gonad protein isolates from three species of sea urchin possess various functionalities and therefore can be potentially applied in food system. Practical Application: Sea urchin M. nudus, G. crenularis, and S. intermedius gonads are edible, whereas the functional properties of protein isolates from sea urchin gonad remain unknown. In this case, the extraction and comparison of three species of sea urchin gonad protein isolates will not only confirm functional properties but also screen food ingredients with suitable functions. In this study, functionalities of protein isolates derived from M. nudus, G. crenularis, and S. intermedius gonads would provide potential application in bakery food and meat products or as emulsifier candidates in food system. [ABSTRACT FROM AUTHOR]

Abstract This article reported the gelation and microstructural properties of scallop male gonads hydrolysates (SMGHs) in the presence of κ-Carrageenan (κ-C) and treated or untreated with potassium chloride (KCl). The presence of κ-C significantly increased the elastic moduli (10.3–449.5 Pa) and melting temperature (32.7–46.7 °C) of SMGHs. The decrease in the relaxation time (T 21 , T 23) signified the strong binding between SMGHs and κ-C. The blue shift in the amide I and II peals coupled with a new band of 1159 cm−1 in SMGHs/κ-C further demonstrated the electrostatic interactions between SMGHs and κ-C. κ-C rose the percentage of β-sheets from 28.10% to 35.93% but at the expense of α-helix and β-turn fractions and highly ebbed the intrinsic fluorescence of SMGHs. Such scenarios resulted in a more compact network formation and flocculation of κ-C chains. The salt-treatment to κ-C promoted helical formation, however, presence of SMGHs created larger interstitial spaces in the κ-C network due to aggregates of SMGHs and decreased the overall gel strength. The outcome promises novel opportunities in the design and development of functional hydrogels based on protein and polysaccharide complexes for food, pharmaceutical and biomedical applications. Graphical abstract Image 1 • Synergistic effectongelation occursbetweenκ-carrageenan(κ-C)and SMGHs. • Synergistic effect of κ-C on SMGHs may be attributed to the water migration in gel system. • Positive patches of SMGHs and sulfate groups of κ-C entangle by electrostatic interaction. • κ-C-κ-C connections hold the entire networkwhile SMGHsentrapintothisnetwork. • SMGHs appear to create larger interstitial spaces inκC/KClnetwork decreasinggel strength. [ABSTRACT FROM AUTHOR]

Abstract In order to provide a foundation for comprehensive utilization of scallop (Patinopecten yessoensis) , the gel properties of hydrolysates from scallop male gonad (SMGHs) were studied. The hydrolysates were obtained from scallop male gonads (SMGs) by using trypsin. The changes in molecular mass of proteins were determined by SDS-PAGE and HPLC with a peptide separation column. The gel properties of SMGHs were investigated by using rheometer and texture instrument in comparison with that of ι-carrageenan and gelatin. The results showed that the proteins of SMGs were significantly degraded after hydrolysis with trypsin at a dosage of 3000 U/g protein. The SMGHs showed an appearance of gelation after hydrolysis for 30–180 min and cooling down. Under various sweep models, the values of storage modulus (G′), loss modulus (G″), viscosity (ƞ) of SMGHs were obvious higher than those of SMGs. The textural parameters containing firmness, cohesiveness and adhesive force of SMGHs at dosages of 50 and 75 mg/mL were similar to those of ι-carrageenan and gelatin at 25 mg/mL, respectively. For the mixtures, the gel property of SMGHs/ι-carrageenan SMGHs/gelatin increased significantly. The low-field NMR (LF-NMR) also reflected the T 23 of SMGHs/ι-carrageenan, T 21 of SMGHs/ι-carrageenan and SMGHs/gelatin mixture decreased significantly in comparison with SMGHs alone. These results suggest that SMGHs could be applied as a potential gelling and thickening agent in food formulations. Graphical abstract Image 1 Highlights • SMGHs treated by trypsin showed a specific gel property caused by peptides. • Gel property of SMGHs had hydrolysate time- and hydrolysate dose-dependent manners. • Gel strength of SMGHscan be comparable with ι-carrageenan and gelatin. • Synergistic effect on gelation was occurred betweenι-carrageenanand SMGHs. • Synergistic effect on water migration was foundbetweenι-carrageenanand SMGHs. [ABSTRACT FROM AUTHOR]

In order to provide the fundamental basis for control and application of sea cucumber autolysis, the contribution of cathepsin L to intestinal proteolysis in sea cucumber (Stichopus japonicus) was investigated. Cathepsin L mRNA expression was significantly up-regulated by 1.80 ± 0.44-fold with ultraviolet irradiation (p< 0.05). According to the protein pattern identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and determination of the release of trichloroacetic acid (TCA)-soluble oligopeptide, high intestinal protein degradation was observed at pH 4.4 and 48°C. Intestinal protein proteolysis was strongly inhibited by cathepsin L inhibitors, including trans-epoxysuccinyl-L-leucyl-amido (4-guani-dino)butane (E-64), iodoacetic acid (IA), and antipain (AP). These results imply that cathepsin L is involved in intestinal autolysis in the sea cucumber S. japonicus. Abbreviations: TCA: trichloroacetic acid; Z-Phe-Arg-AMC: Z-Phe-Arg-7-amido-4-methylcou-marin; IA: iodoacetic acid; E-64: trans-epoxysuccinyl-L-leucyl-amido (4-guanidino) butane; AP: antipain; SBTI: soybean trypsin inhibitor; SDS-PAGE: sodium dodecyl sulfate polyacrylamide gel electrophoresis; RT-PCR: reverse transcription-polymerase chain reaction [ABSTRACT FROM AUTHOR]

In the present study, the rheological behavior of hydrolysates from scallop male gonad hydrolysates (SMGHs) was studied. The hydrolysates were obtained from scallop male gonads (SMGs) using papain. The changes in molecular mass of proteins in SMGHs were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that the proteins of SMGs were significantly degraded after hydrolysis with papain. The degree of hydrolysis reached to 17.8% and 20.8% for SMGHs treated by papain at 300 and 3,000 U/g protein, respectively. The SMGHs exhibited a weak strain overshoot behavior as well as non-Newtonian shear thinning flow behavior. Moreover, the rheological properties of SMGHs possessed a papain dose-dependent manner. These results suggest that SMGHs could be applied as a potential gelling and thickening agent in food formulations. [ABSTRACT FROM AUTHOR]

The objective of the present study was to improve the utilization of scallop ( Chlamys farreri ) byproducts by using Maillard reaction. Scallop mantle hydrolysates (SMHs) were prepared using neutrase then reacted with ribose. Thirty-four peptides were identified from SMHs by UPLC-Q-TOF-MS, and the abundance of Asp and Lys suggested the strong Maillard reactivity. The formation of Schiff’s base as well as modification of amide I, II and III bands in Maillard reaction products (MRPs) was confirmed by ultraviolet–visible, fluorescence, and Fourier transform infrared spectroscopy. Thirty volatile compounds were produced by the reaction of SMHs with ribose. Moreover, MRPs with enhanced radical scavenging and anti-linoleic acid peroxidation activities over SMHs promoted the survival and reduced the DNA damage of HepG2 cells treated with hydrogen peroxide. These results suggest that SMHs-ribose MRPs can be potentially used as food antioxidant for suppressing of lipid oxidation or protecting of cell from oxidative damage. [ABSTRACT FROM AUTHOR]

• Gellan gum (GG) improved gel formation of protein isolate from P. crocea roe (pcRPI). • GG improved the rheological properties and water holding ability of pcRPI gels. • The pcRPI-GG binary gels showed denser, more aggregated network structure. • GG improved the protective effects of curcumin by pcRPI gels with control release. The aim of this study was to investigate the effect of gellan gum (GG) on the cold gelation of large yellow croaker roe protein isolate (pcRPI). The water-holding ability and storage modulus of the pcRPI-GG binary gels increased with the GG concentration, where the storage modulus of the pcRPI-0.2% GG gel was approximately 30.7 times that of the pure pcRPI gel. Compare to the other binary gels, pcRPI-0.2% GG gels exhibited a lower lacunarity and higher junction density, with a denser, more aggregated microstructure. Consequently, curcumin was embedded in pcRPI-0.2% GG gels, and simulated gastrointestinal digestion test results showed that GG addition effectively protected and slowed curcumin release in the gastrointestinal environment. These findings may contribute to elucidating the interaction of pcRPI with GG and demonstrate the potential of binary gels for the embedding and delivery of active substances. [ABSTRACT FROM AUTHOR]

The combination of scallop male gonads hydrolysates (SMGHs) and κ -carrageenan (KC) was applied for curcumin (Cur) embedment and preservation, the corresponding Cur retention rate as well as gelation and microstructural properties were investigated during storage subjected to various pH (8 and 6) and temperature (25 °C and 4 °C). SMGHs-based gels could well protect Cur from degradation during 4 °C storage, with retention rate ranging from 95% to 97% after 30 day storage. At 25 °C, Cur could still be well preserved in SMGHs-based gels under pH 6 with Cur retention rate above 90%, while pH 8 led to rapid Cur degradation to around 75%. In addition, at pH 8 and 25 °C, the gel strength of SMGHs-Cur deteriorated significantly while evidently enhanced in SMGHs/KC-Cur due to synergistic combination within SMGHs and KC in couple with dehydration effect. Moreover, the water migration and distribution of SMGHs-based Cur-loaded vehicles were relatively stable at 4 °C while revealed apparent deterioration at 25 °C during storage. Furthermore, the microstructures of SMGHs/KC-Cur gradually transformed from homogeneous network with dense and smooth pores to tattered network with large and fragmentary pores, especially at 25 °C, promoting more Cur degradation. This study demonstrated that SMGHs/KC-Cur exhibited better than SMGHs-Cur in Cur preservation, potentially performing as excellent and sustainable protein hydrolysate/polysaccharide soft materials in food and biomedical fields. [Display omitted] • Acidic and low temperature are favorable for Cur protection in SMGHs-based vehicles. • SMGHs/KC performs better Cur preservation than SMGHs above 98% at 4 °C after 30 day. • Enhanced gel strength of SMGHs/KC-Cur after pH 8, 4 °C storage is due to dehydration. • Water migration and distribution are stable at 4 °C while deteriorate at 25 °C. • Compact and dense porous networks of SMGHs/KC allow more Cur retention at 4 °C. [ABSTRACT FROM AUTHOR]

• Scallop male gonad hydrolysates (SMGHs) have potential as gel matrix. • Synergistic effects between SMGHs and two nonionic polysaccharides were determined. • SMGHs and nonionic polysaccharides developed a hydrogel with exceptional viscosity. • Hydrogen bonding and hydrophobic interaction are dominant forces in the mixed gels. The involvement of hydrogen bonding and hydrophobic interactions in a mixture of scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and guar gum (GG) or locust-bean gum (LBG) was investigated using guanidine hydrochloride (GuHCl) and urea treatments in this study. The addition of GG and LBG (5.56 mg/mL) increased the viscosity of SMGHs at 0.1 s-1 by almost 2.5-fold and 1.7-fold, respectively, reaching 254.8 and 177.0 Pa·s. After treatment with GuHCl or urea, the mixed gels (SMGHs/GG and SMGHs/LBG) became relatively transparent and more fluid, as the viscosity significantly reduced. Moreover, changes of moisture distribution and conformational characteristics suggested that hydrogen bonding and hydrophobic interactions were the main intermolecular forces in the mixed gels of SMGHs and GG or LBG. Furthermore, the SMGHs/GG and SMGHs/LBG mixtures yielded strong gels with viscous network structures, indicating that these materials can be used as thickening agents in food systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • -Ca2+ and K+ binding to IC promotes gelation of AK/IC with dose-dependent manner. • -Different state of water in AK/IC could resist the salt interference. • -AK/IC mediated by salts appears well honeycomb structures and even denser under Ca2+. • -AK/IC mediated by salts exhibits highly aggregation and entanglement fibers chains. • -Hydrogen bonding combined electrostatic interactions govern the salt-mediated AK/IC. The gelation and microstructural behaviors of Ala-Lys dipeptide/iota-carrageenan (AK/IC) mediated by salts were investigated. Obviously, salt addition prominently exaggerated the synergistic gelation between AK and IC, with storage modulus (G') of AK/IC and IC increasing extensively from 1145 to 9516 Pa or 5919 Pa and from 615 to 9981 Pa or 4693 Pa at 0.1 Hz with 0.5 % CaCl 2 or KCl, respectively, in which CaCl 2 revealed superiority over KCl. Additionally, different states of water in AK/IC gels resisted salt interference. Moreover, a honeycomb structure with denser porous networks coupled with rough entanglement morphology of AK/IC was observed, in which the CaCl 2 -treated group exhibited even smaller pore sizes. The conformational changes of AK/IC induced by salts were reflected by the redshift of –OH groups in AK/IC, insinuating salt-mediated H-bonding in AK/IC. The blueshift of amide I bands and water deformation groups of AK/IC in comparison to AK and IC alone illustrated the electrostatic interactions between them. Furthermore, coordination interaction, hydrogen bonds and hydrophobic interactive were highlighted among IC, AK and CaCl 2 /KCl as reflected by molecular docking. [ABSTRACT FROM AUTHOR]

A composite hydrogel composed of scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and κ -carrageenan (KC) was fabricated with a designed microstructure to preserve curcumin (Cur) during the upper gastrointestinal tract (GIT). The presence of KC obviously increased the initial elastic moduli (8.2–761.8 Pa), shortened the relaxation time T 23 (517.37–420.10 ms) as well as caused the blue shift of the emission peak and quenched the intrinsic fluorescence of Cur in SMGHs/KC-Cur system, signifying the solid combination within SMGHs and KC. In addition, the red shift in O–H stretching bands and blue shift in amide I bands in SMGHs/KC-Cur further accentuated the involvement of hydrogen bonds and electrostatic interactions within SMGHs, KC and Cur. The disappearance of crystalline structures suggested the successful embedment of Cur in the hydrophobic core of SMGHs. Moreover, the microstructure of the hydrogels varied from heterogeneous with tattered large pore cavities and scattered patches to homogeneous distribution with dense mesh and solid network wall. These scenarios caused a more compact network of SMGHs/KC-Cur than SMGHs-Cur to protect Cur from releasing in simulated intestinal and simulated colonic phases with slower released rate, both of which had the final extent of Cur release exceeding 90%. Furthermore, cryo-SEM showed that the significant release of Cur from hydrogels in the simulated intestinal phase was due to SMGHs matrix erosion with even larger pore sizes, tattered network and thinner network wall. Therefore, it is suggested that SMGHs/KC hydrogels with biocompatibility and good tolerance to acid environment could be reliable and desirable soft materials to embed and deliver Cur to the colon, having potential applications in functional foods and biological therapeutic purposes. [Display omitted] - Enhancement of gel elasticity in SMGHs/KC confirmed a feasible Cur-loaded carrier. - Migration of water in SMGHs/KC to bound water direction supported the Cur embedment. - Compact and dense porous networks of SMGHs/KC contributed to the Cur embedment. - Better sustained release of Cur in SMGHs/KC promised the delivery of Cur in colon. [ABSTRACT FROM AUTHOR]

The purpose of this study was to characterize the electrostatic complexation between scallop Patinopecten yessoensis male gonad hydrolysates (SMGHs) and κ -carrageenan/xanthan gum (KC/XG) within pH 12–1 at different hydrolysate/polysaccharide ratios (9:1–1:9) and to investigate the influence of pH and ratios on gelation and microstructural properties for widening the application of marine-derived source. According to the phase diagram of SMGHs/KC/XG, pH c hold a constant value around pH 8.5, pH φ1 gradually shifted from 4.2 to 2.8, and pH max fluctuated within 2.4-1.4 as ratios decreasing from 9:1–2:8. Additionally, SMGHs/KC/XG showed higher gel strength in acid condition, as decreasing pH promoted the electrostatic attractive interactions within positively charged patches in SMGHs and negatively charged sulfate and carboxyl groups in KC/XG causing more tightly packed structures formation. Moreover, decreasing ratios from 9:1 to 3:7 could further enhance the gel strength of SMGHs/KC/XG, ascribing to the stronger gelation ability of polysaccharides and enough neutralization. Moreover, SMGHs/KC/XG exhibited well-organized microstructures with smaller pore sizes, denser and more homogeneous networks at more acid domains, supporting stronger gel strength. Therefore, this study provides theoretical and methodological basis for designing novel SMGHs/KC/XG hydrogels with considerable gel strength and microstructures through understanding the complex coacervation at different pH and ratios. • pH and ratio largely regulate turbidity changes of SMGHs/KC/XG complexes. • pH c exhibits ratio-independent, and pH φ1 , pH max exhibit ratio-dependent behaviors. • Higher KC/XG proportion supports stronger gel strength in soluble phases. • More SMGHs/KC/XG neutralization promotes gel formation in insoluble coacervate phase. • SMGHs/KC/XG exhibits well-organized and compact networks at acid condition. [ABSTRACT FROM AUTHOR]

• pH and ratio largely governed turbidity changes of SMGHs/ κ -C complexes. • pH c exhibited ratio-independent, and pH φ1 , pH max exhibited ratio-dependent behaviors. • SMGHs aggregates and agglomerated SMGHs/ κ -C support the gel strength at acid pH. • SMGHs/ κ -C at acid pH had greater interaction with water to support the gel formation. • SMGHs/ κ -C formed a denser network at acid pH with stronger gel strength. The electrostatic complex coacervation between scallop Patinopecten. yessoensis male gonad hydrolysates (SMGHs) and κ -carrageenan (κ -C) were monitored by using turbidimetry at various pH (1–12) and biopolymer mixing ratio (9:1–1:9). The pH c exhibited ratio-independent behavior, and pH φ1 , pH max exhibited ratio-dependent behavior, respectively. The decreasing ratio enhanced the gel strength of SMGHs/ κ -C at higher pH while inversely at lower pH, ascribing to more SMGHs aggregates and stronger neutralization between positively charged patches in SMGHs and κ -C at lower pH and higher ratio. Moreover, SMGHs/ κ -C gel at acid condition exhibited lower relaxation times (T 21 and T 23). Furthermore, the rheological and relaxation time T 2 data were well associated with microscopy images which indicated that SMGHs/ κ -C gel showed a well-distributed network structure at more acidic domains, supporting stronger gel rigidity and water-holding capacity. [ABSTRACT FROM AUTHOR]

• Complex coacervation of SMGHs/ κ -C is largely governed by NaCl/KCl. • pH c and pH φ1 exhibited salt-dependent behaviors. • Optical density of SMGHs/ κ -C was regulated by salt-enhanced and -reduced effect. • Salt addition enhanced SMGHs/ κ -C gels mainly driven by electrostatic forces. • SMGHs/ κ -C showed more flocculation, larger pore and thicker network wall with salt. The complex coacervation between scallop Patinopecten yessoensis male gonad hydrolysates (SMGHs) and κ -carrageenan (κ -C) as influenced by ionic strength (NaCl and KCl) were monitored by using turbidimetric analysis at pH 1–12. The optical density of SMGHs/ κ -C complexes initially increased at lower ionic strength (0–0.5 M) whereas decreased at higher ionic strength (0.5–1.5 M) as a result of the salt-enhanced and salt-reduced effect, respectively. Both of pH c and pH φ1 exhibited ionic strength-dependent behavior that firstly shifted to acidic pH followed by an increase as salt increasing. Moreover, salt addition strongly promoted the gelation of SMGHs/ κ -C which was mainly driven by electrostatic forces, as reflected by increasing storage modulus G' from 3621 to 6559 Pa, 2681–25631 Pa at 0.1 Hz and decreasing T 23 relaxation time from 349.10 to 296.89 ms, 241.07–186.89 ms by 0–0.5 M NaCl/KCl, respectively. Furthermore, the rheological and relaxation time T 2 data were well associated with microscopy images that SMGHs/ κ -C gels with NaCl/KCl showed a denser network with more flocculation formation and larger pore sizes with thicker network wall, especially in KCl group, which indeed supported the gel elasticity. Taken together, this study could provide theoretical and methodological basis for new functional hydrogel products with modified gel strength and microstructure by understanding the complex coacervation in gel system. [ABSTRACT FROM AUTHOR]

The purpose of this study was to construct calcium cross-linked gelatinized lotus rhizome starch (LRS)/sodium alginate (SA) hydrogel beads of adjustable quality and to reduce the digestibility of gelatinized starch. LRS was mixed with SA, gelatinized by heating and subsequently cross-linked with Ca2+ to form hydrogel beads. The digestibility of the gelatinized LRS could be adjusted by changing the dose of SA in the hydrogel beads. When the LRS/SA ratio was 4/6, the rapidly digested starch (RDS) content in the beads was reduced by 26.9% compared with gelatinized LRS alone, whereas the slowly digested starch (SDS) and resistant starch (RS) contents increased by 12.3-fold and 2.3-fold, respectively. In addition, the water distribution in the Ca2+-crosslinked LRS/SA hydrogel bead samples also showed an SA dose dependence. With increasing SA concentration, the ability of the hydrogel beads to immobilize water increased. The diffusion of Ca2+ into the interpenetrating polymer network that was prepared with gelatinized LRS and SA gradually resulted in gelation dominated by ion bonds, leading to the heterogeneous microstructure of the hydrogel beads, which also involved intermolecular hydrogen bond interactions. Overall, the present study suggested a strategy for developing novel LRS hydrogel bead systems for quality control and gelatinized starch digestibility downregulation by adjusting the SA dose, which provided insights for the innovation of personalized and convenient starchy products in the food industry. [Display omitted] • Gelatinized lotus rhizome starch (LRS) was used to construct hydrogel beads. • Ca 2+ -crosslinked LRS/sodium alginate (SA) beads formed interpenetrating network. • There are mainly hydrogen and ion bonds in the Ca 2+ -crosslinked LRS/SA bead. • Digestibility of the LRS/SA hydrogel beads were SA dose dependent. [ABSTRACT FROM AUTHOR]

To investigate the impact of different polyphenols on the gel properties of gellan gum (GG) and the interaction mechanism, experiments and virtual molecular simulations were conducted based on nine representative polyphenols. Rheological analysis revealed that all the GG/polyphenol composite hydrogels were pseudoplastic fluids with a low viscosity. The storage modulus (G′) of hydrogel containing only GG was 28.3 Pa at 0.1 Hz. The addition of gallic acid (GA), puerarin (PUE) or cyanidin cation (CC) significantly increased the G′ of the hydrogel by 4.9-fold, 3.3-fold, and 2.6-fold, respectively. The introduction of GA reduced the water holding capacity (WHC) of the hydrogel to 62.0 %, while the other eight polyphenols increased the WHC to nearly 100 %. Regular, intact and dense honeycomb mesh structures were observed in the GG/GA, GG/PUE, GG/CC and GG/catechin microstructures. The molecular docking results indicated that, among the nine polyphenols, PUE had the strongest affinity for GG with an interaction energy of −18.64 kcal/mol. According to the results of molecular dynamics simulation, the total energy of the composite system interacting with water corresponded well with the G′ of the composite hydrogels. The GG/GA system with the highest G′ had the lowest total energy of −15655.82 kJ/mol. Hydrogen bonds were the main driving force for improving the strength and maintaining the structural stability of the composite hydrogels. Therefore, this study confirmed the various effects of nine polyphenols on GG hydrogels and provided a novel basis for investigating the synthesis and gelation mechanism of polysaccharide-polyphenol composite hydrogels. [Display omitted] • The properties of GG hydrogel varied after mixed with different polyphenols. • Molecular docking elucidated affinity and binding modes between GG and polyphenols. • Relationship between gel strength and binding energy provided by MD simulations. • Hydrogen bonding played major roles in gel formation and binding process. [ABSTRACT FROM AUTHOR]

BACKGROUND: Laboratory scale experiments have shown that curdlan and gellan gum gelled together as curdlan/gellan gum (CG) hybrid gels showed better gel properties than the individual curdlan and gellan gum. In this study, CG and black wolfberry anthocyanin (BWA), CG and maltitol (ML) hybrid gels were constructed using CG hybrid gel as matrix. The effects of BWA or ML on the gel properties and microstructure of CG hybrid gels were investigated and a confectionery gel was developed. RESULTS: The presence of BWA increased the storage modulus (G') value of CG at 0.1 Hz, whereas ML had little effect on the G' value of CG. The addition of BWA (5 g L−1) and ML (0.3 mol L−1) increased the melting and gelling temperatures of CG hybrid gels to 42.4 °C and 34.1 °C and 44.2 °C and 33.2 °C, respectively. Meanwhile, the relaxation time T22 in CG‐ML and CG‐BWA hybrid gels was reduced to 91.96 and 410.27 ms, indicating the strong binding between BWA and CG, ML and CG. The hydrogen bond interaction between BWA or ML and CG was confirmed by the shift in the hydroxyl stretching vibration peak. Moreover, the microstructures of CG‐ML and CG‐BWA hybrid gels were denser than that of CG. In addition, confectionery gel containing CG‐BWA‐ML has good chewing properties. CONCLUSION: These results indicated that the incorporation of BWA or ML could improve the structure of CG hybrid gels and assign a sustainability potential for the development of confectionery gels based on CG complex. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Electrostatic complex coacervation between chia seed gum (CSG) and whey protein isolate (WPI) under different pH values (8-1), WPI/CSG mass ratios (16:1-1:1, w/w), and NaCl concentrations (0–400 mM) was investigated. Stronger complexation occurred at relatively high mass ratios (16:1, 8:1, and 4:1) and pH below the isoelectric point of WPI. Moreover, the complexation of WPI and CSG was weakened after adding NaCl and completely suppressed at 400 mM NaCl. Complexation with CSG decreased the α-helix and β-turn contents, increased the β-sheet content, and reduced the fluorescence intensity and surface hydrophobicity of WPI. The results of phase behavior and structural alteration suggested that the strongest electrostatic interaction occurred at pH 4, mass ratio 4:1, and 0 mM NaCl. The thermal stability of WPI/CSG complex coacervates was improved in comparison with that of WPI. Furthermore, rheological data and microscopy images indicated that stronger interactions between WPI and CSG resulted in greater viscosity and viscoelastic modulus, as well as denser structures. This study offers a theoretical reference for developing innovative and functional food products via understanding the interactions between WPI and CSG under different conditions. [Display omitted] • The complex coacervation between WPI and CSG occurred by electrostatic interaction. • The complexation was controlled by pH, WPI/CSG mass ratio, and NaCl concentration. • The addition of NaCl weakened the intensity of electrostatic complexation. • Hydrogen bonds and hydrophobic interactions also participated in the complexation. • A stronger complexation led to higher viscoelastic properties and denser network. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the properties of ternary composite gel of scallop (Patinopecten yessoensis) protein hydrolysates (SMGHs)/κ‐carrageenan (KC)/xanthan gum (XG). The rheological properties, moisture‐distribution, molecular structure, and microstructure of SMGNs/KC/XG gels were analyzed. The results showed that the G′ value, melting temperature, and water holding capacity of SMGHs/KC/XG were higher than those of SMGHs, SMGHs/KC, and SMGHs/XG. FTIR spectrum showed the generation of hydrogen bonds between SMGHs and KC/XG, and the carboxylic acid group of XG interacts with SMGHs. Moreover, the cryo‐SEM results showed that SMGHs/KC/XG exhibited a tighter, smoother, and more aggregated microstructure than those of SMGHs, SMGHs/KC, and SMGHs/XG. These results indicate that the gel and microstructural properties of SMGHs are significantly improved by addition of KC and XG, and SMGHs/KC/XG has potential to be used as functional hydrogels for food, pharmaceutical, and biomedical applications. Practical Application: Scallop (Patinopecten yessoensis) male gonads are rich in protein and usually regarded as byproducts during adductor processing. Because of its gelation properties, scallop male gonads have potential to be used as functional hydrogels for food. The SMGHs/KC/XG ternary composite gel showed excellent gel properties, which would be potentially applied in delivery system in food and biological fields. Further study is undergoing to apply SMGHs/KC/XG to embed bioactive compounds, such as curcumin and β‐carotene. [ABSTRACT FROM AUTHOR]

Gel properties of hydrogel-forming by Ala-Lys dipeptide (AK) and iota-carrageenan (ι-C) were investigated by rheological behavior, fourier transform infrared analysis, cryo-scanning electron microscopy, low field-NMR relaxometry and magnetic resonance imaging. Iota-carrageenan was changed from a liquid to a gel with the addition of AK, and the existence of AK significantly increased the storage modulus (G') of ι-C from 590.4 to 1077.8 Pa. In the ι-C/AK gel, the blue-shift of O H stretching and water deformation were observed, meanwhile, the presence of amide I band at 1682 cm−1 was observed. The network of ι-C/AK gel showed a dense honeycomb structure with flocculating continuous phase and rough entanglement morphology. After adding AK, the water free in the pores of ι-C entered the ι-C/AK gel matrix, and the binding capacity of bound water was enhanced. These scenarios proved that the AK as the cationic dipeptide could control the conversion of negatively charged ι-C from an original random structure to a helical structure due to electrostatic interactions and hydrogen bonds. This study provides a new opportunity for the peptides into carbohydrate-based gel matrices, which could provide insights for the further application of ι-C/AK gels in the fields of food industry, tissue engineering and drug delivery. • AK dipeptide enhanced the gel properties of iota-carrageenan. • Electrostatic interactions was the main force in AK/ ι-C gel. • The hydrogen bond stabilized the AK/ι-C gel structure. • AK induced regular and homogenous network structure in the ι-C gel. [ABSTRACT FROM AUTHOR]

Natural polymeric proteins, isolated from scallop gonad, had already shown promise as a potent nutraceutical. The purpose of this study was to fabricate scallop gonad protein isolates (SGPIs) as a natural alternative emulsifier designed for improving the physicochemical stability of β-carotene (BC). The influence of carrier oil, including long- and medium-chain triglycerides (LCT/MCT), on the physicochemical stability of BC emulsions was investigated. The SGPI-stabilized BC emulsions were characterized in terms of viscosity, particle diameter, zeta-potential, atomic force microscopy (AFM), cryogenic scanning electron microscopy (cryo-SEM), and confocal laser scanning microscopy (CLSM). Compared to SGPI-MCT emulsions, SGPI-LCT emulsions had better resistance to high ionic strengths and thermal treatment. During the 30-day storage period, the particle diameter, zeta-potential, and BC degradation of both emulsions had a great change at 37 °C than at 25 or 4 °C, and the variation of SGPI-MCT emulsions was more obvious than that of SGPI-LCT, which could be attributed to the high viscosity of SGPI-LCT emulsions. These results indicate that SGPIs can be applied in protecting lipophilic bioactives by using emulsion-based systems, in which LCT oil was more effective for encapsulating and protecting BC than MCT oil. [ABSTRACT FROM AUTHOR]

In this study, hydrolysates of large yellow croaker (Pseudosciaena crocea) roe were prepared by trypsin (Try‐pcRHs) and papain (Pap‐pcRHs). The degree of hydrolysis (DH), molecular weight distribution and iron chelating capacity of hydrolysates were investigated. Moreover, the chelation mechanism of iron‐hydrolysates complex also was investigated by amino acid composition analysis, fourier transform infrared spectrophotometer, fluorescence spectrophotometer and ultraviolet–visible spectroscopy. These results showed that Try‐pcRHs exhibited higher iron chelating ability with the EC50 value of 0.14 mg/ml than Pap‐pcRHs, which may be due to the higher DH and content of peptide <1 KDa. Furthermore, the Asp, Glu, Ser, Pro, Ile, Phe and His in Try‐pcRHs might contribute to the chelation reaction, and the groups of ‐COOH, C=O, N‐H and C‐O were involved in chealtiong of Try‐pcRHs with iron. Therefore, Try‐pcRHs have the potential to be used as iron supplements in food industries. Practical Applications: Large yellow croaker (Pseudosciaena crocea) roes are the main by‐products in the large yellow croaker processing. Previous studies have found that protein isolates from P. crocea roes composed of vitellogenin B, vitellogenin C and vitellogenin contain a large number of serine residues. In this study, we prepared hydrolysates from large yellow croaker roes, and the results showed that trypsin‐hydrolyzed large yellow croaker roes exhibited great iron‐chelating ability and has the potential to be used as a safe and healthy iron supplements in the food industry. [ABSTRACT FROM AUTHOR]

Calcium β-hydroxy-β-methylbutyrate (CaHMB), a functional calcium salt, is used to maintain and improve muscle health. Here, a new hydrogel material prepared from alginate (ALG) with three M/G ratios (1:1, 2:1, and 1:2) and CaHMB (0–2 mg/mL) was investigated. CaHMB regulates the formation and properties of ALG hydrogels through chelation and hydrogen bonding. When the M/G ratio was 2:1, the anionic groups of CaHMB containing carboxyl and hydroxyl groups formed hydrogen bonds with the polysaccharide chains, hindering the capture of Ca2+ by the G-residue fragments of ALG, which in turn retarded the gelation process. The noncalcium cross-linked polysaccharide chain structure of ALG and the anionic group of CaHMB also affected the water distribution in the hydrogel, especially when M residue content ≥G residue content. Lower M/G ratios and higher CaHMB concentrations could increase the number of "egg box" crosslinking junctions of calcium alginate, and the microstructure was denser in the gel pores, resulting in a stronger gel strength and more free water bound in the gel matrix. This study provides a theoretical and methodological basis for the design of novel hydrogels by studying the crosslinking features of ALG/CaHMB. • Alginate and calcium β-hydroxy-β-methylbutyrate (ALG/CaHMB) successfully form gels. • Hydrogen bonds between anionic groups of CaHMB and ALG delay the gel formation. • More guluronate residues enhance the crosslinking density forming denser networks. • Higher CaHMB concentrations promote the formation of more "egg box" structures. [ABSTRACT FROM AUTHOR]

In the present study, the effects of corn starch (CS) on the properties of Chinese shrimp (Fenneropenaeus chinensis) powder (SP) were characterized to explore the feasibility of developing dysphagia diet. The SP/CS gels were prepared by adding CS at different concentrations. The SP/CS mixture presented low gel properties at CS concentrations ranging from 12 to 48 mg/mL, but did demonstrate gelation behavior with the highest G′ value of 1134.2 Pa and a water holding capacity of 90% at 60 mg/mL. As the CS concentration increased, the stability of the SP/CS mixture also improved, as evidenced by the significantly reduced relaxation times T 22 and T 23 , enhanced gel network formation, and the presence of hydrogen bonding and electrostatic interactions between SP and CS. Furthermore, the international dysphagia diet standardisation initiative (IDDSI) swallowing level of the SP/CS mixtures were 2, 3, 4, and 5 at CS concentrations of 12, 24, 36, 48 and 60 mg/ml, respectively. The SP/CS-60 mixture gel was considered suitable for dysphagia patients. These findings suggest that the gel properties of SP can be modified by CS, and that the SP/CS mixture gels have the potential to be used as a texture-modified diet with high-quality protein for dysphagia patients. [Display omitted] • The gel properties of SP/CS were positively correlated with the concentration of CS. • CS increased the elasticity and water holding capacity of SP. • CS promoted water migration to bound water in SP and enhanced the gel network. • SP/CS (each at 60 mg/mL) gel was suitable for dysphagia patients. [ABSTRACT FROM AUTHOR]

This study investigated the gelation of scallop male gonad hydrolysates (SMGHs) modified with sodium dodecyl sulfonate (SDS) and three polysaccharides, including κ -carrageenan (KC), ι -carrageenan (IC), and gellan gum (GG), and the film-forming properties were further evaluated. The transparency of SMGHs was improved by SDS in a dose-dependent manner, while the gel properties were disrupted. In this case, the gelling properties could be improved by introducing KC, IC, and GG, as reflected by 3.1–5.1 folds increment in G′ , 1.5–1.9 folds increment in hardness, 4%–6% increment in springiness, 19%–24% reduction in T 23 , and higher proton densities. In addition, the blueshift of SMGHs/SDS/polysaccharide amide II bands suggested increased electrostatic interactions within SMGHs and each polysaccharide. These scenarios could be ascribed to the compact and well-distributed network of SMGHs/SDS/polysaccharide. Furthermore, SMGHs-based ternary composite gels with desirable optical and mechanical properties could be applied as films in the food industry. [Display omitted] • A significant gel synergy was detected between polysaccharides and SMGHs/SDS. • SMGHs/SDS/polysaccharides exhibited shortened T 23 and higher proton densities. • SMGHs/SDS/polysaccharides were governed by hydrogen bonds and electrostatic forces. • SMGHs/SDS/polysaccharides composite gels exhibited dense and homogeneous microstructures. • SMGHs/SDS/GG film had good performance in both optical and mechanical properties. [ABSTRACT FROM AUTHOR]

In the present study, the synergetic gelation of curdlan gum (CG) and gellan gum (CG) at different biopolymer ratios were investigated. The optimal gelation of CG and GG was determined at total biopolymer concentration of 0.6% and a mass ratio of 1:1 according to visual observation and viscoelastic properties. The gelation behavior of the CG/GG binary composite gel exhibited ratio-dependent behavior at different biopolymer mixing ratios (2:8–8:2). With the increase in the CG/GG ratio from 2:8 to 8:2, the gel strength and transition temperature of the CG/GG gel showed an increasing trend followed by a decrease, reaching a peak at 5:5, with corresponding G′ , melting and gelling temperatures of 335.8 Pa, 82.5 °C and 33.7 °C, respectively. The improved gel properties could be ascribed to hydrogen bonds between CG and GG, as reflected by the blueshift of the O–H vibration peaks and water associated regional variation. Moreover, the CG/GG binary composite gel exhibited a significantly increasing water holding capacity (WHC) as the ratio of CG/GG decreased from 8:2 to 4:6, while the excess involvement of GG had no effect on the WHC improvement. Furthermore, the CG/GG binary composite gel exhibited denser and more homogeneous microstructures in comparison to individual CG and GG and performed the most compact gel network at ratio of 5:5, supporting the stronger gel rigidity and WHC. Therefore, these novel CG/GG hydrogels showed considerable gel strength and microstructures, which would provide a better mechanistic understanding of the polysaccharide complex in practical applications as a hydrogel base material. [Display omitted] • The addition ratio between CG and GG exhibited a significant effect on the synergy. • CG/GG binary composite gels exhibited good water holding capacity. • The CG/GG binary composite gels mainly driven by hydrogen bonding forces. • The CG/GG binary composite gels exhibited dense and homogeneous microstructures. [ABSTRACT FROM AUTHOR]

To develop composite hydrogels based on low acyl gellan gum (GG), the effect of puerarin (PUE) on the gel properties of GG was investigated. The results showed that the maximum storage modulus (G ′) of the 1.2 % GG/0.8 % PUE composite hydrogel was 377.4 Pa at 0.1 Hz, which was enhanced by 4.7-fold compared with that of 1.2 % GG. The melting temperature of this composite hydrogel increased from 74.1 °C to >80.0 °C. LF-NMR results showed that a significant amount of free water was present in the hydrogel matrix. The surface structure aggregation and the shrinkage of the honeycomb meshes in the composite hydrogel proved the cross-linking of PUE and GG. XRD, FTIR and molecular simulation results illustrated that hydrogen bonds were the most important factor controlling the interaction between GG and PUE. Thus, the GG/PUE composite hydrogel has good elasticity, thermal stability and water retention, which lays a good foundation for further application in the food industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Large yellow croaker (Pseudosciaena crocea) roe is the main by‐product in the processing of large yellow croaker. Previous studies have found that its protein isolates are composed of vitellogenin, as well as vitellogenin B and C, having good functional properties. (‐)‐Epigallocatechin‐3‐gallate (EGCG) is a natural antioxidant component that can be combined with protein to improve antioxidant activity and structural characteristics of protein. RESULTS: EGCG was bound with the P. crocea roe protein isolate (pcRPI) by the free radical method to prepare the conjugate. The formation of pcRPI–EGCG conjugates was confirmed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and gel permeation chromatography, which showed that the calculated weight‐average molar masses of native‐pcRPI and pcRPI–EGCG conjugates were 86.9 and 215.3 kDa, respectively. The results of fluorescence, ultraviolet, circular and infrared spectra indicated that the conjugation of EGCG with native‐pcRPI changed the secondary and tertiary structure of native‐pcRPI. The pcRPI–EGCG conjugates exhibited higher thermal stability than native‐pcRPI. The radical scavenging and reducing power of native‐pcRPI were increased by 2.0–2.5‐ and 1.4‐fold, respectively, after the EGCG‐grafting reaction. CONCLUSION: These results indicate that the binding of pcRPI and EGCG effectively improved the antioxidant properties and structural characteristics of the pcRPI. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Here, a novel decapeptide IVTNWDDMEK with Maillard reactivity derived from scallop Chlamys farreri mantle was identified. The structural characteristics and in vitro hepatoprotective effects of IVTNWDDMEK conjugated with ribose were further investigated. The changes in decapeptide structures were determined by ultraviolet–visible (UV–vis), Fourier transform infrared (FTIR), and atomic force microscopy (AFM), and the modification sites induced by Maillard reaction of IVTNWDDMEK and ribose were monitored by high performance liquid chromatography/tandem mass spectrometry (HPLC‐MS/MS). Maillard reaction products (MRPs) of IVTNWDDMEK‐ribose demonstrate hepatoprotective benefits through the suppression of DNA damage and apoptosis induced by oxidative stress in human HepG2 cells in addition to enhancing the antioxidant activities. Moreover, after treatment with decapeptide‐ribose MRPs, the activities of cellular antioxidative enzymes, such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), and glutathione reductase (GSH‐Rx) were remarkably increased, while the content of malondialdehyde (MDA) was decreased compared with H2O2‐treated group, thereby enhancing the intracellular antioxidant defenses. These findings demonstrate the potential utilization of decapeptide IVTNWDDMEK‐ribose MRPs as food antioxidants to suppress oxidative damage. Practical Application: In recent years, several food‐derived bioactive peptides and their derivatives are regarded as good dietary antioxidants for reducing oxidative stress and improving liver function. Here, a novel Maillard reactive decapeptide IVTNWDDMEK, identified from scallop mantle hydrolysates by peptidomics in the previous study was synthesized. Then, the correlation between intercellular antioxidant activities and chemical structure changes of IVTNWDDMEK‐ribose Maillard reaction conjugates was further studied. The preferable hepatoprotective activities of decapeptide IVTNWDDMEK‐ribose MRPs indicated that these MRPs could be potentially utilized as food antioxidants or additives in the production of nutritional foods. [ABSTRACT FROM AUTHOR]

Seafood traceability is an important means of ensuring the quality of local seafood. Jellyfish are an important edible resource with a large yield on a global scale. Different species of pickled jellyfish, a traditional Chinese food, cannot be differentiated solely from the appearance of the product due to its special processing methods. In this paper, two species of jellyfish, R. esculentum and S. meleagris , were identified by PCR-RFLP technique. The genetic identification of the jellyfish R. esculentum and S. meleagris was based on PCR amplification of a common 651 bp fragment of the 16S rRNA gene, followed by digestion of four restriction enzymes, Hind III, Hpa I, Xho I and Dra I, respectively. The results showed that the two species of fresh jellyfish could be identified clearly, as could the pickled R. esculentum. To verify this result, PCR-RFLP was applied to authenticate four kinds of commercial pickled jellyfish. The electrophoretogram clearly showed that R. esculentum and S. meleagris were easily and accurately authenticated. This PCR-RFLP system has the potential to become an effective method for identifying the jellyfish products from Liaoning Province of China. • Seafood traceability is an important means to ensure the quality of local featured seafood. • Jellyfish is an important edible resource as palatable food for thousands years. • Fresh jellyfish must be processed into dry goods sales, known as pickled jellyfish. • PCR-RFLP method have high sensitivity and validity for provenance identification. [ABSTRACT FROM AUTHOR]

Protein isolates were recovered from scallop (Patinopecten yessoensis) gonads to develop a novel functional matrix by investigating their physiochemical and functional properties. Scallop gonad protein isolates (SGPIs) were prepared from degreased scallop gonads (DSGs) by an alkali extraction and isoelectric solubilization/precipitation (ISP) process. The protein compositions of the SGPIs were mainly vitellogenin and beta‐actin with molecular weights of 266 and 42 kDa, respectively, as determined using Nano‐liquid chromatography‐mass/mass (Nano‐LC‐MS/MS). After the ISP process, the protein solubility of the SGPIs was significantly improved, and the surface hydrophobicity of SGPIs intensely increased by 1.1‐fold, which were attributed to the exposure of aromatic residues such as phenylalanine, tyrosine, and tryptophan. However, the content of total/reactive sulfhydryl in SGPIs was decreased compared with that of DSGs. Meanwhile, the ISP process caused partial protein unfolding, as indicated by circular dichroism analysis, which exhibited a remarkable rise in the β‐sheet content with a parallel decline in the α‐helix and random coil contents (P < 0.05). SGPIs exhibited a better oil absorption capacity and foaming property than both DSGs and soybean protein isolates (SPIs). Moreover, the emulsifying capacity of SGPIs was greatly enhanced by the ISP process, which was superior to the effect of commercial SPIs and was ascribed to its favorable solubility as well as surface characteristics. Practical Application: During the processing of scallop (Patinopecten yessoensis) adductors, scallop gonad, a high‐protein part, is usually discarded as processing by‐products despite its edibility. In recent years, scallop gonads are regarded as good sources to develop protein matrices due to their high protein content and numerous nutrients. In this study, scallop gonad protein isolates (SGPIs) were isolated by isoelectric solubilization/precipitation (ISP) process. The preferable solubility, foaming property coupled with high emulsifying property of SGPIs indicated that the SGPIs could be potentially utilized as a good protein emulsifier and additives in production of kamaboko gels, hamburger patties, sausages, and pet foods. [ABSTRACT FROM AUTHOR]

In order to improve the utilization of scallop byproducts, scallop female gonad hydrolysates (SFGHs) were prepared using alcalase and ribose at a mass ratio of 1:2 and pH 7.0 (95°C, up to 12 h) to develop heterogeneous Maillard-type antioxidant and flavor compounds. The formation of Schiff's base as well as modification of the amide bands in Maillard reaction products (MRPs) were investigated using ultraviolet–visible, fluorescence, and Fourier transform infrared spectroscopy. The significant decrease of amino acid residues explained the strong Maillard reactivity of SFGHs. MRPs with enhanced ABTS+ radical scavenging capacity over SFGHs promoted the survival of HepG2 cells treated with hydrogen peroxide. Moreover, 19 new volatile compounds were produced by the reaction of SFGHs with ribose. These results suggest that SFGHs–ribose MRPs can be potentially used as antioxidants with flavor properties. Abbreviations: SFGs: scallop female gonads; SFGHs: scallop female gonad hydrolysates; ABTS: 2ʹ2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid); BHT: butylated hydroxytoluene; Trolox: 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; MRPs: Maillard reaction product; H2O2: hydrogen peroxide; HS-SPME/GC/MS: Headspace solid phase micro-extraction/gas chromatography/mass spectrometry. [ABSTRACT FROM AUTHOR]

Maillard reaction products (MRPs) were produced in sea cucumber gut hydrolysates (SCGHs)-ribose system at 75°C, 85°C, and 95°C with a pH value of 7.0 or 8.0 for 12 hour. The parameters of amount of intermediate products, fluorescence intensity, browning development, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability showed a positive correlation with each other in SCGHs-ribose system. The amount of intermediate products, fluorescence intensity, and browning development followed the zero-order kinetic with activation energy from 62 to 91 kJ/mol in the Maillard reaction of SCGHs-ribose system. Moreover, 2-methyl-butanal has positive and significant correlation with DPPH radical scavenging ability of SCGHs-ribose MRPs. These results suggest that Maillard reaction improves the antioxidant activity of SCGHs, which contributes to the generation of intermediate, fluorescent, browning, and volatile products of SCGHs-ribose system. [ABSTRACT FROM PUBLISHER]

• Protein isolates (pcRPIs) and lipids (pcRLs) of large yellow croaker roes were extracted simultaneously. • The purity of pcRPIs was greater than 70% with vitellogenin, vitellogenin B and vitellogenin C as main proteins. • pcRLs were mainly composed of triglyceride with high level of EPA and DHA content. • pcRPIs exhibited better physicochemical and functional properties than pcR. • pcRPIs had the better oil holding capacity and emulsifying abilities than soy protein isolate. The objective of this study was to simultaneously obtain protein isolates and lipids from the dried powder of large yellow croaker (Pseudosciaena crocea) roes (pcRs) to achieve high-value utilization. Protein isolates and lipids were extracted simultaneously from pcRs by saline and acidic solutions. The purity of the protein isolates from the pcRs (pcRPIs) was greater than 70%, with vitellogenin, vitellogenin B and vitellogenin C as the main proteins. The lipids from pcRs (pcRLs) were mainly composed of triglycerides with high levels of EPA and DHA. The pcRPIs exhibited a higher surface hydrophobicity, water/oil holding capacity and emulsifying ability than those of the pcRs. Moreover, pcRPIs had a better oil holding capacity and emulsifying ability than soy protein isolate. These results suggest that protein isolates and lipids can be simultaneously extracted by saline and acidic solutions, and pcRPIs and pcRLs can be used as functional materials in the food industry. [ABSTRACT FROM AUTHOR]

Protein isolate of sea cucumber guts (SCGPI) was extracted from defatted power of sea cucumber guts (SCGs) by alkaline extraction and acid precipitation method. The physicochemical and functional properties of SCGPI were evaluated in comparison with those of SCGs. It was found that the SCGPI showed higher whiteness, and contained 39.5% of the essential amino acids with higher protein efficiency ratio. The functionalities of SCGPI, including solubility, water/oil holding capacity (WHC/OHC), foaming capacity (FC), and emulsifying abilities (EAI), were significantly higher than those of SCGs. SCGPI exhibited higher total sulfhydryl group, disulfide bond, β‐turns, and random coil, while less surface hydrophobicity and α‐helix than SCGs. The thermal denaturation temperature of SCGPI was 46.55°C and the microstructure of SCGPI was flaky. Moreover, OHC, FC, and EAI of SCGPI were significantly better than those of SPI. These results suggest SCGPI can be used as functional bases in the food industry. Practical applications: Sea cucumber (Stichopus japonicus) guts are the main byproducts in the sea cucumber processing, which are rich in protein. In this study, we prepared protein isolate from sea cucumber guts (SCGPI) by alkaline extraction and acid precipitation method. The results showed that SCGPI exhibited great solubility, water/oil holding capacity, foaming capacity, and emulsifying abilities. The present study demonstrates that SCGPI can be used as a functional base in the food industry. [ABSTRACT FROM AUTHOR]