Characteristics of high-internal-phase emulsion gel stabilized by micellar casein–pectin/chitosan oligosaccharide

Abstract

Emulsion gels prepared from single proteins or polysaccharides generally suffer from poor stability, while conventional emulsion gels also exhibit deficiencies such as complicated preparation processes and high production costs. In this study, using micellar casein (MC) as the matrix and anionic polysaccharide pectin (P) or cationic polysaccharide chitosan oligosaccharide (CO) as fillers, we prepared an O/W high-internal-phase emulsion gel with a 75% oil-phase volume fraction via a simple one-step homogenization method. The results demonstrate that the storage stability of the MC-based emulsion gels was significantly enhanced with the addition of P/CO. The average oil droplet size decreased from 42.77 ± 16.15 μm for the MC-based emulsion gel to 22.68 ± 4.31 μm for the MC–P emulsion gel at 6:4 ratio and 27.04 ± 8.07 μm for the MC–CO gel at 9:1 ratio. The water-holding capacity increased from 75.08 ± 1.33% for pure MC gels to 89.62 ± 2.24% for MC–P emulsion gels at a MC-P ratio of 6:4. The incorporation of P also improved the thermal stability of the gels. Furthermore, CO addition exerted a more pronounced enhancement of the pH stability of emulsion gels compared to P, particularly under acidic conditions. The incorporation of P or CO increased the viscosity and viscoelasticity of the MC-based emulsion gels. Hydrogen bonds and electrostatic interactions were the main interactions maintaining the strength of the MC–P-based emulsion gels and MC–CO gels, respectively. The findings of this study not only provide a reference for the preparation and application of emulsion gels stabilized by MC–P/CO, but they also offer new insights into the mechanisms by which intermolecular interactions regulate the stability and rheological properties of MC-based emulsion gels.