Effects of sodium carboxymethyl cellulose on rheological properties and gelation behaviors of sodium alginate induced by calcium ions

Different concentrations of sodium carboxymethyl cellulose (CMC) were added into 1.0 g/100 g sodium alginate to investigate the rheological properties and gelation behaviors of the composite gel. Gluconic acid-δ-lactone (GDL) was used to release Ca 2+ ions to induce uniform gel formation by sodium alginate. The effects of CMC on critical gelation behavior during sodium alginate gelation were discussed. The sodium alginate/CMC composite gel is still a shear thinning fluid, and its viscosity is positively related to CMC content. When CMC content is higher than 0.4 g/100 g, the composite viscosity (η*) differs from the apparent viscosity (η), and η* remains at higher level than η. When CMC content is lower than 0.2 g/100 g, the gelation of sodium alginate accelerates, and the gelation strength increases. However, when CMC content is higher than 0.4 g/100 g, the gelation accelerates, but the gelation strength decreases with increasing CMC. The gel point of sodium alginate (ƒ gel ) is delayed with increasing CMC. The critical exponent differs greatly when CMC content is higher than 0.2 g/100 g, and the system loses self-similarity at the gel point. The fractal dimension of the composite gel increases initially and then decreases with increasing CMC. The system develops the densest structure at 0.4 g/100 g CMC content.