Phase behavior and process parameters effect on grape seed extract encapsulation by SEDS technique

Grape seed extract (GSE) was encapsulated in biocompatible poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) using the solution enhanced dispersion by supercritical fluids (SEDS) technique. In order to help selecting the appropriate operating conditions for the encapsulation mechanism, the fluid phase behavior of pseudo-ternary carbon dioxide (CO2) + dichloromethane (DCM) + GSE systems was studied employing a static synthetic method. The investigated SEDS operating parameters were in the following range: pressure (8-12 MPa), temperature (308-318 K), GSE to PHBV mass ratio (1:1-1:3), with concentrations of organic solution formed by GSE (6.67-20.00 kg m−3) in DCM, and fixed PHBV 20.00 kg m−3 in DCM. The organic solution flow rate was fixed at 1.67 × 10−8 m3 s−1 and the antisolvent flow rate at 3.33 × 10−7 m3 s−1. The effect of operating parameters on particle size, particle morphology and encapsulation efficiency was checked. The best result was obtained at 8 MPa, 308 K, GSE to PHBV mass ratio of 1:1, with concentration of GSE and PHBV, both of 20.00 kg m−3, leading to spherical particles with the smallest size of ∼0.70 μm and encapsulation efficiency of 66.01%. SEM-EDS micrographs showed that, besides spherical particles, agglomerated particles were observed at temperatures higher than 308 K, which might be due to a more favorable extract re-dissolution at higher temperatures.