Precipitation and encapsulation of β-carotene in PHBV using carbon dioxide as anti-solvent

Abstract

The main objective of this work was to investigate the application of supercritical carbon dioxide as anti-solvent for the encapsulation of β-carotene in poly(hydroxybutirate-co-hydroxyvalerate) (PHBV) with dichloromethane as organic solvent using the Solution Enhanced Dispersion by Supercritical fluids (SEDS) technique. For the precipitation experiments with pure compounds the parameters investigated were the concentration of β-carotene (4 and 8 mg mL −1) and PHBV (30 mg mL −1) in the organic solution, pressure (from 80 to 200 bar), solution flow rate fixed at 1 mL min −1, anti-solvent flow rate at 40 mL min −1 and constant temperature of 313 K. Pure β-carotene precipitation indicates that an increase in pressure led in most cases to particles with larger sizes, while the opposite trend was verified for pure PHBV precipitation. The morphology of precipitated PHBV particles was spherical and was not influenced by increasing pressure. The morphology of β-carotene microparticles changed from plate-like to leaf-like particles when raising operational pressure, but was not influenced by its concentration in the organic solution as verified by micrographs of scanning electronic microscopy (SEM). For the co-precipitation experiments it was evaluated the effect of β-carotene concentration (2–30 mg mL −1) in the organic solution, at fixed parameters: PHBV concentration (30 mg mL −1) in organic solution, temperature at 313 K, pressure at 80 bar, solution flow rate at 1 mL min −1 and anti-solvent flow rate at 40 mL min −1. The encapsulation data showed that increasing the concentration of β-carotene, keeping fixed the PHBV content, results in higher percentage of solute encapsulated, increasing the encapsulation efficiency.