Mechanism of multicyclic β-carotene impregnation into corn starch aerogels via supercritical CO2 with mathematical modeling

Abstract

β-carotene, a natural dye renowned for its antioxidant and provitamin A activities, is hindered from direct use in food and drug products due to its susceptibility to oxidation, easy isomerization under light, heat, or acidic conditions, as well as its low water solubility and oral bioavailability. In this study, we addressed these challenges by loading β-carotene into corn starch aerogels via supercritical carbon dioxide (sc-CO2) and assessed its loading contributions through adsorption during contact time and precipitation during depressurization. The loading process was studied under two cycles at pressure of 30 MPa, temperature of 40 °C, depressurization rate of 0.4 MPa/min, and co-solvent (ethanol) mass percentage of 1.2 %. Experiments found adsorption minimally contributed to impregnation, while precipitation became the primary loading mechanism. The subsequent work focused on a mathematical model describing β-carotene loading into corn starch aerogels via precipitation, using the law of conservation of mass and classical nucleation theory. The model shows that using pure CO2 results in a loading efficiency of 0.10 mg β-carotene/g aerogel, while with CO2 and 1.2 % ethanol as the co-solvent, the loading efficiency increases threefold to 0.30 mg β-carotene/g aerogel.