Evaluation of the stability of pea and canola protein-based hydrogels in simulated gastrointestinal fluids

This work aims to investigate the effect of polyelectrolyte complexation (PEC) on the stability of proteinalginate hydrogels in simulated gastrointestinal fluids. The properties of two types of hydrogels based on pea protein isolates (PPI) and on canola protein isolates (CPI) were compared. The molecular structure of hydrogels was assessed by FTIR and their thermal stability was tested by DSC and TGA. The swelling capacity of hydrogels was tested in distilled water, simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) without enzymes. CPI beads showed higher swelling capacity than PPI beads in all swelling media. In SIF, relatively higher swelling, an increase in volume and partial degradation were observed for all hydrogel beads. In addition, the swelling of beads in SIF was found to be dependent on PEC with chitosan. Moreover, degradation tests in SGF and SIF media with enzymes were performed to assess the effect of PEC on the stability of hydrogels. The results indicated that PEC had no influence on the stability of hydrogels in SGF but significantly delayed the degradation of hydrogel under SIF conditions. These findings suggest that PEC could be utilized to modify protein-alginate hydrogels to create matrices for prolonged release applications. (C) 2015 Elsevier Ltd. All rights reserved.