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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]

In this study, cold-set large yellow croaker (Pseudosciaena crocea) roe protein isolate (pcRPI) gels were prepared by glucono-δ-lactone (GDL) at different concentrations. The 0.1% and 0.2% GDL induced pcRPI at 50 mg/mL to form cold-set gels, while pcRPI suspension with 0.4% GDL addition still showed a fluid state. The pcRPI gel induced by 0.2% GDL showed better rheological properties and its G' value was about 5.1 times than that of 0.1% GDL. In addition, pcRPI gels induced by 0.1% and 0.2% GDL showed similar water holding capacity, and 0.2% GDL-induced pcRPI gels showed a special T 2 peak in 2249.0 ms which might represent free water on the surface of the gel. Furthermore, the higher total number of junctions, vessels percentage area, and lower lacunarity indicated a denser three-dimensional network structure in pcRPI gels induced by 0.1% and 0.2% GDL. Particle size tests and AFM results further confirmed that GDL induced pcRPI to form cold-set gels by promoting the formation of protein aggregates. Therefore, 0.1–0.2% GDL are suitable to prepare pcRPI cold-set gels. These results may deepen the understanding on cold-set pcRPI gels induced by GDL. • Pseudosciaena crocea roe protein isolates (pcRPI) had potential to form cold-set gels. • 0.2% glucono-δ-lactone (GDL)-induced pcRPI gels showed good rheological properties. • The 0.1–0.2% GDL induced pcRPI gels had a dense three-dimensional network structure. • GDL-induced pcRPI gels were promoted by the formation of protein aggregates. [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]