Supercritical antisolvent micronisation of synthetic all-trans-β-carotene with tetrahydrofuran as solvent and carbon dioxide as antisolvent

BACKGROUND: Supercritical antisolvent (SAS) micronisation of synthetic trans-β-carotene was studied using tetrahydrofuran (THF) as solvent and supercritical carbon dioxide (CO₂) as antisolvent, with the objective of increasing its bioavailability and facilitating its dispersion in oil and emulsion formulations as a result of its smaller particle size. The micronised powder was analysed by scanning electron microscopy and high-performance liquid chromatography. Micronisation experiments were performed in order to evaluate the effects of temperature (308.15-333.15 K), pressure (6.5-13 MPa) and concentration of the liquid solution (6-9 g L⁻¹). The effect of the supercritical CO₂/THF flow ratio in the range between 4 and 44 (on a mass basis) was also analysed. Determinations of equilibrium concentrations of β-carotene in the CO₂/THF mixture were also performed.RESULTS: The particle size obtained ranged from 1 to 500 μm, with mean particle diameters around 100 μm. Three types of morphology were found in the precipitated powder: crystalline with superficial pores and leaf-like appearance; crystalline with regular shapes and blade-like edges; and crystalline without superficial pores and leaf-like apearance. The Peng-Robinson equation of state was used to calculate the density of the CO₂/THF binary mixture, and the solubility of β-carotene in this mixture was correlated with its density.CONCLUSION: The use of the SAS technique to micronise β-carotene proved to be efficient, and the absence of degradation in the micronised powder allows the industrial application of this technique. Copyright