Investigation of the formation mechanism and β-carotene encapsulation stability of emulsion gels based on egg yolk granules and sodium alginate.

The formation mechanism of heat-induced egg yolk granules (EYGs)/sodium alginate (SA) emulsion gel was studied under pH 6.2 and 7.5. Particle size, water holding capacity, LF NMR, and protein solubility revealed that pH 7.5 increased the surface charge of EYGs and enhanced non-covalent interaction with SA, and hydrogen bonding dominated of the gel formation process. Microscopy and rheological analysis indicated that samples with 0.75% SA had the smallest particle size and highest G', with chain-like oil droplets. Excess SA (1%) led to depletion flocculation due to SA structural rearrangements around oil droplets caused by the increase in negatively charged, causing uneven network structure. The in vitro release property and storage stability of β-carotene loaded in the EYGs/SA emulsion gel showed that SA increased storage stability and decreased bioaccessibility of β-carotene with delayed digestion rate. These results provide a theoretical basis for the nutrient delivery system in gel foods.