Dispersing hydrophobic natural colorant β-carotene in shellac particles for enhanced stability and tunable color

Color is one of the most important visual attributes of food and is directly related to the perception of food quality. The interest in natural colorants, especially β-carotene that not only imparts color but also has well-documented health benefits, has triggered the research and development of different protocols designed to entrap these hydrophobic natural molecules to improve their stability against oxidation. Here, we report a versatile microfluidic approach that utilizes single emulsion droplets as templates to prepare microparticles loaded with natual colorants. The solution of β-carotene and shellac in the solvent is emulsified by microfluidics into droplets. Upon solvent diffusion, β-carotene and shellac co-precipitates, forming solid microparticles of β-carotene dispersed in the shellac polymer matrix. We substantially improve the stability of β-carotene that is protected from oxidation by the polymer matrix and achieve different color appearances by loading particles with different β-carotene concentrations. These particles demonstrate great promise for practical use in natural food coloring.