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Electrostatic complex coacervation between chia seed gum (CSG) and whey protein isolate (WPI) under different pH values (8-1), WPI/CSG mass ratios (16:1-1:1, w/w), and NaCl concentrations (0–400 mM) was investigated. Stronger complexation occurred at relatively high mass ratios (16:1, 8:1, and 4:1) and pH below the isoelectric point of WPI. Moreover, the complexation of WPI and CSG was weakened after adding NaCl and completely suppressed at 400 mM NaCl. Complexation with CSG decreased the α-helix and β-turn contents, increased the β-sheet content, and reduced the fluorescence intensity and surface hydrophobicity of WPI. The results of phase behavior and structural alteration suggested that the strongest electrostatic interaction occurred at pH 4, mass ratio 4:1, and 0 mM NaCl. The thermal stability of WPI/CSG complex coacervates was improved in comparison with that of WPI. Furthermore, rheological data and microscopy images indicated that stronger interactions between WPI and CSG resulted in greater viscosity and viscoelastic modulus, as well as denser structures. This study offers a theoretical reference for developing innovative and functional food products via understanding the interactions between WPI and CSG under different conditions. [Display omitted] • The complex coacervation between WPI and CSG occurred by electrostatic interaction. • The complexation was controlled by pH, WPI/CSG mass ratio, and NaCl concentration. • The addition of NaCl weakened the intensity of electrostatic complexation. • Hydrogen bonds and hydrophobic interactions also participated in the complexation. • A stronger complexation led to higher viscoelastic properties and denser network. [ABSTRACT FROM AUTHOR]

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 Ca2+ 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. • Alginate and calcium β-hydroxy-β-methylbutyrate (ALG/CaHMB) successfully form gels. • Hydrogen bonds between anionic groups of CaHMB and ALG delay the gel formation. • More guluronate residues enhance the crosslinking density forming denser networks. • Higher CaHMB concentrations promote the formation of more "egg box" structures. [ABSTRACT FROM AUTHOR]

In the present study, the synergetic gelation of curdlan gum (CG) and gellan gum (CG) at different biopolymer ratios were investigated. The optimal gelation of CG and GG was determined at total biopolymer concentration of 0.6% and a mass ratio of 1:1 according to visual observation and viscoelastic properties. The gelation behavior of the CG/GG binary composite gel exhibited ratio-dependent behavior at different biopolymer mixing ratios (2:8–8:2). With the increase in the CG/GG ratio from 2:8 to 8:2, the gel strength and transition temperature of the CG/GG gel showed an increasing trend followed by a decrease, reaching a peak at 5:5, with corresponding G′ , melting and gelling temperatures of 335.8 Pa, 82.5 °C and 33.7 °C, respectively. The improved gel properties could be ascribed to hydrogen bonds between CG and GG, as reflected by the blueshift of the O–H vibration peaks and water associated regional variation. Moreover, the CG/GG binary composite gel exhibited a significantly increasing water holding capacity (WHC) as the ratio of CG/GG decreased from 8:2 to 4:6, while the excess involvement of GG had no effect on the WHC improvement. Furthermore, the CG/GG binary composite gel exhibited denser and more homogeneous microstructures in comparison to individual CG and GG and performed the most compact gel network at ratio of 5:5, supporting the stronger gel rigidity and WHC. Therefore, these novel CG/GG hydrogels showed considerable gel strength and microstructures, which would provide a better mechanistic understanding of the polysaccharide complex in practical applications as a hydrogel base material. [Display omitted] • The addition ratio between CG and GG exhibited a significant effect on the synergy. • CG/GG binary composite gels exhibited good water holding capacity. • The CG/GG binary composite gels mainly driven by hydrogen bonding forces. • The CG/GG binary composite gels exhibited dense and homogeneous microstructures. [ABSTRACT FROM AUTHOR]