Construction and properties of curdlan gum/gellan gum binary composite gel system

Abstract

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.