Abstract: In this study, β-carotene-loaded protein emulsion was prepared and then used to prepare hydrogel microparticles cross-linked with different concentrations of Ca2+. The influence of Ca2+ crosslinking on the basic properties and stability of hydrogel microparticles was investigated. It turned out that there were no significant differences in the particle size of hydrogel microparticles cross-linked with different concentrations of Ca2+. Both the viscosity and gel strength of hydrogel microparticles increased with the increase of Ca2+ concentration. The cross-linked hydrogel microparticles had better centrifugal stability. There was an obvious phase separation in the emulsion at pH 3–5, while the hydrogel microparticles were relatively stable to at pH 3–7. A slight phase separation occurred in the cross-linked hydrogel microparticles with a low concentration of Ca2+ (0–2 mmol/L) at high salt levels (> 2 mol/L NaCl). However, the cross-linked β-carotene-loaded hydrogel microparticles with 2–4 mmol/L Ca2+ concentrations were stable at different salt levels. In the storage experiments, the retention of β-carotene in the hydrogel microparticles was higher than in the emulsion, and it was improved by Ca2+ cross-linking.

Key words: β-carotene, emulsion, hydrogel microparticles, stability