Structure of gellan gum-hydrolyzed collagen particles: Effect of starch addition and coating layer

In this work, we developed biopolymeric structures, based on electrostatic attraction, through dripping gellan gum into hydrolyzed collagen (HC), to deliver hydrophilic compounds. Moreover, we evaluated the influence of starch addition on the polymeric network as well as the coating effects promoted by an outer gellan layer. The lowest tested gellan gum concentration in the core (0.5% w/w) was the best one to build spherical beads, with high retention of bioactives (>84% for anthocyanin and >68% for HC). Moreover, the minimum HC concentration (2.5% w/w) in the gelling bath allowed the saturation of active sites of gellan gum presented in the core, as regardless of the HC concentration in the peptide bath, particles presented the same amount of adsorbed peptide. Starch disturbed the interactions between HC and gellan, increasing porosity and pore size, but it presented an important role in retaining anthocyanin in the particle's core. Finally, we demonstrated that addition of a gellan coating layer affected the structure of beads: Peptide molecules (positively charged), already adsorbed onto the beads, diffused out of the core, attracted by the negatively charged gellan coating layer. Consequently, it decreased particle size and increased pore size in the outer part of the particles, which was associated with a reduction in the retention of bioactives. These findings bring important contributions to particle engineering: A new process for particle production was proposed, in which hydrogels were produced by dripping the polysaccharide into the protein bath to be externally gelled, without previous crosslinking with salts.