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Simple Summary: Sea cucumbers are very sensitive to the influence of environmental factors, and will vomit their intestines and undergo tissue degradation under certain stimuli. In order to determine the effect of endogenous enzymes in the sea cucumber intestine on the body wall during body wall softening, intestine extracts and crude collagen fibers were prepared, respectively. The endogenous enzymes belonging to serine proteases were identified by gelatin zymography. The rheological property results showed that the addition of sea cucumber intestinal extracts reduced the viscosity of crude collagen fibers from 32.7 Pa·s to 5.3 Pa·s. The serine protease inhibitor phenylmethylsulfonyl fluoride inhibited the activity of intestinal extracts, and maintained the viscoelasticity of crude collagen fibers. In this paper, endogenous enzymes in sea cucumber intestinal extracts were identified as serine endopeptidases, which caused softening of the body wall. Sea cucumbers Apostichopus japonicus will vomit their intestines during certain stimulations, and the collagen of the body wall will then be degraded. To define the effect of the sea cucumber intestine extracts on the body wall, the intestinal extracts and crude collagen fibers (CCF) of sea cucumber A. japonicus were prepared. According to the gelatin zymography, the type of endogenous enzymes in intestinal extracts were mainly serine endopeptidases with optimal activities at pH 9.0 and 40 °C. According to the rheology results, the viscosity of 3% CCF decreased from 32.7 Pa·s to 5.3 Pa·s by adding intestine extracts. The serine protease inhibitor phenylmethanesulfonyl fluoride inhibited the activity of intestinal extracts and increased the viscosity of collagen fibers to 25.7 Pa·s. The results proved that serine protease in the intestinal extracts participated in the process of body wall softening in sea cucumbers. [ABSTRACT FROM AUTHOR]

The mosquito Aedes albopictus can transmit various arboviral diseases, posing a severe threat to human health. As an environmentally friendly method, sterile insect technology (SIT) is considered an alternative to traditional methods such as chemical pesticides to control Ae. albopictus. In SIT, the sterility of male mosquitoes can be achieved by γ-ray or X-ray radiation. Compared with γ-rays, X-rays are easier to obtain, cheaper, and less harmful. However, there is a lack of comparative assessment of these two types of radiation for SIT under the same controlled conditions. Here, we compared the effects of X-ray and γ-ray radiation on the sterility of Ae. albopictus males under laboratory-controlled conditions. Neither type of radiation affected the number of eggs but significantly reduced the survival time and hatch rate. The same dose of γ-rays caused a higher sterility effect on males than X-rays but had a more significant impact on survival. However, X-rays could achieve the same sterility effect as γ-rays by increasing the radiation dose. For example, X-rays of 60 Gy induced 99% sterility, similar to γ-rays of 40 Gy. In the test of male mating competitiveness, the induced sterility and the male mating competitiveness index were also identical at the same release ratio (sterile males/fertile males). At a release ratio of 7:1, nearly 80% of eggs failed to hatch. Sterile males produced by X-ray and γ-ray radiation had similar male competitiveness in competition with field males. In conclusion, a higher dose of X-rays is required to achieve the same sterility effect, compared to γ-rays. When γ-rays are not readily available, high-dose X-rays can be used instead. This study provides data supporting the selection of more suitable radiation for the field release of sterile male mosquitoes. [ABSTRACT FROM AUTHOR]

The gel properties and microstructure of scallop male gonad hydrolysates (SMGHs) were investigated by combing with κ‐carrageenan (κ‐C) and locust bean gum (LBG). It was shown that the initial elastic module of SMGHs/κ‐C 0.1 Hz got marked improvement from 202.3 Pa to 326.7 Pa and the melting temperature also increased 6°C with the addition of LBG. According to the data of low‐field nuclear magnetic resonance, the relaxation time T23 markedly reduced in SMGHs/κ‐C/LBG, representing the migration of water might result in a strong bind among SMGHs, κ‐C, and LBG. Fourier transform infrared spectroscopy showed the existence of hydrogen bonding between LBG and SMGHs/κ‐C. Low‐temperature scanning electron microscopy showed that the SMGHs/κ‐C/LBG ternary complexes possessed smaller voids and more dense network structures. These results could provide more possibilities for the application of SMGHs and polysaccharide complexes in functional hydrogel development. Novelty impact statement: We evaluated the gel and microstructure properties of ternary composite gel consisted of protein hydrolysates from male gonad of scallop (Patinopecten yessoensis) (SMGHs), κ‐carrageenan (κ‐C), and locust bean gum (LBG). The results showed that the addition of κ‐C and LBG significantly improved the gel properties of SMGHs. [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]

The gel properties of scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) combined with different concentrations of iota-carrageenan (ι-C) were studied. SMGHs at 5% (w/v) were dispersed in 0.26%, 0.56% and 1.25% ι-C solution, respectively. The storage modulus value of SMGHs/ι-C increased with the increasing of ι-C concentration and reached 1392.7 Pa for 1.25% ι-C at 0.1 Hz, which was almost 116-fold greater than that of SMGHs. SMGHs combined with different concentrations of ι-C exhibited thermoreversible gel properties with melting and gelling temperatures of 40.2–51.3 °C and 30.6–33.9 °C, respectively. Non-destructive testing of gel samples by low-field nuclear magnetic resonance showed that the degree of water trapping in SMGHs/ι-C was in a ι-C concentration-dependent manner. SMGHs/ι-C showed three-dimensional network structures with a tendency toward denser with increasing of ι-C concentration. The improved gelation by the combination of SMGHs and ι-C as well as controlling the concentration of ι-C can provide information for potential application in food formulation. [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]

Objective: In this paper, the inhibition of protein degradation in autolysis of white shrimp (Penaeus vannamei) surimi by extracts from the coelomic fluid of sea cucumber (Stichopus japonicus), a by-product of sea cucumber processing, was studied. Methods: The protein degradation in autolysis of white shrimp was studied by SDS-PAGE assay. Furthermore, the effect of sea cucumber coelomic fluid and its extracts on white shrimp protein degradation was determined by SDS-PAGE and TCA-soluble oligopeptide assay. Results: The optimal conditions of white shrimp autolysis were incubation at pH 3.0, 50 °C for 2 h. The bond intensities of myosin heavy chain around (200 kDa) and actin around (44.3 kDa) decreased suggesting the protein degradation of white shrimp. The sea cucumber coelomic fluid showed inhibitory effect on protein degradation in autolysis of white shrimp. When the concentration of coelomic fluid extract of sea cucumber was in the range of 6.25% ~ 25.00%, the protein degradation was significantly inhibited. The release of TCA-soluble oligopeptide was also significantly inhibited by coelomic fluid extract at 12.50%~25.00%. Conclusion: Sea cucumber coelomic fluid extracts possess inhibitory effect on protein degradation of white shrimp, indicating suppression of white shrimp surimi autolysis. [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]

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]

In this study, the effect of coelomic fluid isolates (CFIs) from sea cucumbers (Stichopus japonicus) on autolysis of minced muscle tissue of S. japonicus was investigated. The coelomic fluid of S. japonicus at the concentration of 90% showed suppression effects on activities of papain and trypsin with inhibitory rate of 26.6% and 40.4%, respectively. Moreover, the effect of CFIs on autolysis of minced muscle tissue from S. japonicus was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and trichloroacetic acid (TCA)-soluble oligopeptide assay. CFIs exhibited significantly inhibitory effect on autolytic muscle mince samples with inhibitory rate at 56.2–87.2%. Both heat and proteinase treatments did not influence the inhibitory effect of CFIs on autolysis of minced muscle tissue from S. japonicus. These results suggest that the non-protein and thermally stable substances contribute to the inhibitory effect of CFIs, which can be used to improve sea cucumber quality. [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]

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]

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]

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]

The purpose of the present study was to explore the antioxidant activity of organic extracts from Maillard reaction products (MRPs) of sea cucumber (Stichopus japonicus) gut hydrolysates (SCGHs). The SCGHs were obtained after treatment with neutrase, and they were then reacted with ribose at a mass ratio of 1:2, pH 8.0, and 95 °C for up to 12 h. The MRPs were extracted by methanol and ethanol. The methanol extracts of the MRPs had a higher UV absorbance, browning intensity, and fluorescence intensity than the crude MRPs. The scavenging capacities of methanol and ethanol extracts from MRPs in both 2′,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assays increased significantly (p < 0.05). The methanol extracts were better than the ethanol extracts showing the reduced IC50 levels for ABTS and DPPH by 50% and 50%, respectively. The inhibitory activity for peroxidation of linoleic acid of MRPs was also enhanced in the methanol extracts of MRPs, but this was reduced in ethanol extracts. Moreover, HepG2 cell viability after exposure to the methanol extracts of MRPs was increased to 59.30 ± 0.43% compared with the SCGHs and MRPs, which was 3.97 times that of the H2O2-treated group. These results suggest that methanol extraction can improve the antioxidant activity of SCGHs-ribose MRPs and that the corresponding extracts can be potentially used as food antioxidants. [ABSTRACT FROM AUTHOR]

The characteristics and functional properties of gelatin obtained from Chinese giant salamander (Andrias davidianus) skin were investigated. After alkaline and acetic acid pre-treatment, yield of the gelatin by hot water extraction (60°, 8 h) was 17.63 g/100 g (wet basis), and the gelatin contained 89.46 g/100 g protein, 0.3 g/100 g fat, and 0.41 g/100 g ash (dry basis). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results of the gelatin showed clear band pattern for collagen subunits,β- and α-chains. The gelatin contained 18.85% imino acids, 28.62% hydrophobic amino acids, and 19.68% essential amino acids, which is slightly lower than porcine skin gelatin (PSG). The gelatin exhibited thermo-reversible properties, with gel strength of 192.50 ± 11.47 g, rupture distance of 10.17 ± 0.20 mm, gelling temperature of 4.98°, and melting temperature of 18.04°, Emulsifying activity index (EAI) of the gelatin diminished with increasing concentrations from 10 to 40 mg/mL (p <.05), whereas the emulsifying stability index (ESI) improved significantly (p <.05). Higher concentrations (30 and 40 mg/mL) could significantly enhance the gelatin's foam expansion (FE) and foam stability (FS) (p <.05). Water absorption ability and oil absorption ability of the gelatin were 7.1 g water/g gelatin and 9.8 g oil/g gelatin, respectively. These results imply that the gelatin with good interfacial properties could potentially be used as a novel ingredient in food emulsion systems. Abbreviations: CGSS, Chinese giant salamander skin; CSG, Chinese giant salamander skin gelatin; PSG, porcine skin gelatin; EAI, emulsion activity index; ESI, emulsion stability index; FE, foam expansion; FS, foam stability; WAC, water absorption capacity; OAC, oil absorption capacity. [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]

Scallop female gonad hydrolysates (SFGHs) were prepared by neutrase-hydrolysis. The characteristics and antioxidant activity of Maillard reaction products (MRPs) in SFGHs-sugar model systems were investigated. Results showed that antioxidant-producing MRPs could be prepared by heating SFGHs with ribose in a ratio of 1:2, with an initial pH value of 8.0, and a temperature of 95 °C for 6 h. Kinetics analysis indicated that elevated temperature (55-95 °C) and prolonged time (0-4 h) led to pH lowering of the MRPs, whereas an increase was observed for UV-absorbance, fluorescence intensity, and antioxidant activity. SFGHs-ribose MRPs exhibited excellent DPPH radical scavenging activity and reducing power with IC50 and AC0.5 values of 49.55 and 34.34 µg/mL, respectively. Additionally, SFGHs-ribose MRPs possessed significant protective ability of DNA damage at concentrations above 10 µg/mL. These results implied that the antioxidant activity of SFGHs could be enhanced via Maillard reaction with ribose, and the resulting MRPs might be used as food antioxidants. [ABSTRACT FROM AUTHOR]

To investigate the variation in the condition factor of the sea urchin Strongylocentrotus nudus (S. nudus), gonads were collected in May (MAY), June (JUN), and July (JUL), at the beginning (AUG-b) and end of August (AUG-e). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) detection of the gonads revealed an obvious enhancement of the band at about 37 kDa from July, which was identified as transforming growth factor-beta-induced protein ig-h3 (TGFBI) by nanoLC-ESI-MS/MS. Gonadal proteins were identified by isobaric tagging for relative and absolute quantitation (iTRAQ), and regulation of the identified proteins in pairs of the collected groups was observed. A total of 174 differentially expressed proteins (DEPs) were identified. Seven of the DEPs showed significant correlations with both the gonad index (GI) and protein content. These correlations included 6-phosphogluconate dehydrogenase, decarboxylating isoform X2 (6PGD), CAD protein, myoferlin isoform X8, ribosomal protein L36 (RL36), isocitrate dehydrogenase [NADP], mitochondrial isoform X2 (IDH), multifunctional protein ADE2 isoform X3, sperm-activating peptides (SAPs) and aldehyde dehydrogenase, and mitochondrial (ALDH). However, TGFBI had no correlation with gonad index (GI) or protein content. 6PGD, IDH, multifunctional protein ADE2 isoform X3, and ALDH were shown to interact with each other and might play key roles in changing the condition factor of S. nudus gonads. [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]

To investigate the variation in the condition factor of the sea urchin Strongylocentrotus nudus (S. nudus), gonads were collected in May (MAY), June (JUN), and July (JUL), at the beginning (AUG-b) and end of August (AUG-e). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) detection of the gonads revealed an obvious enhancement of the band at about 37 kDa from July, which was identified as transforming growth factor-beta-induced protein ig-h3 (TGFBI) by nanoLC-ESI-MS/MS. Gonadal proteins were identified by isobaric tagging for relative and absolute quantitation (iTRAQ), and regulation of the identified proteins in pairs of the collected groups was observed. A total of 174 differentially expressed proteins (DEPs) were identified. Seven of the DEPs showed significant correlations with both the gonad index (GI) and protein content. These correlations included 6-phosphogluconate dehydrogenase, decarboxylating isoform X2 (6PGD), CAD protein, myoferlin isoform X8, ribosomal protein L36 (RL36), isocitrate dehydrogenase [NADP], mitochondrial isoform X2 (IDH), multifunctional protein ADE2 isoform X3, sperm-activating peptides (SAPs) and aldehyde dehydrogenase, and mitochondrial (ALDH). However, TGFBI had no correlation with gonad index (GI) or protein content. 6PGD, IDH, multifunctional protein ADE2 isoform X3, and ALDH were shown to interact with each other and might play key roles in changing the condition factor of S. nudus gonads. [ABSTRACT FROM AUTHOR]