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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 Ca 2+ 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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

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 OH 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., (Copyright © 2021 Elsevier B.V. All rights reserved.)

[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]

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]