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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]

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]

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]

[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]

• 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]

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]