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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]

[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]

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]