Hydrogels of starch/carboxymethyl cellulose crosslinked with sodium trimetaphosphate via reactive extrusion

Abstract Hydrogels are materials with advantages in specific applications, such as, retention of food active compounds. This work aims to develop starch (S)/carboxymethyl cellulose (CMC) hydrogels with porous structure, using reactive extrusion to promote crosslinking with sodium trimetaphosphate (STMP). The expansion, porosity, degree of substitution, gel fraction, swelling properties, and FTIR are studied, comparing S, S/CMC, S/STMP, and S/CMC/STMP formulations. Samples containing STMP present the same degree of substitution (0.050 ± 0.001). Higher porosity and percentage of open pores are observed in the mixed hydrogel (S/CMC/STMP). Crosslinking increase the swelling capacity at pH 7, and this property, just like the gel fraction, are sensitive to pH variations. The hydrogel S/CMC present the highest swelling rate compared with the other samples, suggesting strong interaction between components. The reactive extrusion process is efficient to produce starch and starch/CMC hydrogels crosslinked with STMP and the overall results demonstrate the advantages of the mixed hydrogel.