Abstract: Response surface methodology was used to optimize the preparation of β-carotene-loaded zein nanospheres by supercritical anti-solvent technique. The effects of the ratio between β-carotene and zein, temperature, and pressure as well as interactions among them on β-carotene loading and embedding rate were investigated, and the morphology, particle size and structure of β-carotene-loaded zein nanospheres were characterized by SEM, DLS and XRD. The results indicated that core/wall ratio had the most significant effect on β-carotene loading and embedding rate, sequentially followed by pressure and temperature. β-carotene loading reached its maximum level of 8.73%, when the β-carotene/zein ratio was 1:10, the temperature 55 ℃, and the pressure 8 MPa. β-carotene showed a maximum embedded rate of 85.4% under the following conditions: β-carotene/zein ratio of 1:30, temperature of 35 ℃, and pressure of 16 MPa. The structure of β-carotene-loaded zein particles was a matrix, the average particle size was about 150 nm with a narrow distribution, and the spherical degree was high.

Key words: supercritical CO2, β-carotene, zein, response surface methodology