Biopolymer interactions on emulsion-filled hydrogels: chemical, mechanical properties and microstructure

Bioactive carrier systems produced from natural and biodegradable compounds offer diverse applications in the food and drug sector, whether for protection, controlled delivery, texture modification or insertion of lipid compounds into aqueous systems. This study aimed to produce emulsion-filled hydrogels by sonication followed by ionic gelation, containing potato starch as the main compound (gelatinized or native), a low alginate concentration, and gelatin in the continuous phase. Emulsion-filled hydrogels were evaluated regarding chemical and physical structure, as well as morphology of hydrogels after simulated digestion. Slight intensity differences were observed between the FTIR spectra of hydrogels, reflecting water absorption, amorphous and crystalline structures. The chemical characteristics of hydrogels influenced the microstructure and stress at fracture. Hydrogel produced with gelatinized starch was harder than hydrogel with non-gelatinized starch. Regarding digestion assay, we postulated that alginate-gelatin network was degraded by swelling, while alginate-gelatin-starch gels were associated with an erosion mechanism, since its microstructure remained partially stable, only exposing the oil droplets at surface. These findings can provide different delivery and protection mechanisms, allowing varied applications.