Estragole quantity optimization from fennel seeds by supercritical fluid extraction (carbon dioxide–methanol) using a Box–Behnken design : characterization of fennel extracts

Abstract

Oleoresin extraction from fennel seeds using a supercritical fluid extraction (SFE) was carried out. Box–Behnken experimental design was used to optimize the SFE variables: pressure (10, 17.5, and 25 MPa), temperature (313.15, 323.15, and 333.15 K) and time of extraction (1, 2.5, and 4 h). Different percentages of methanol (0, 3, and 6%) were also evaluated to improve the extraction of the corresponding volatile compounds. Besides volatile profile characterization of fennel seeds, the amount of estragole was determined (by gas chromatography-flame ionization detector (GC-FID)) due to its recent concern in being considered a potential carcinogen agent. The optimal values of SFE variables for methanol extracts were high levels of pressure (24 MPa), 333.15 K of temperature, 3.41 h of extraction time, and an intermediate value of methanol percentage (3%), obtaining an optimal value of 1320 ± 260 mg of estragole/kg dry plant. The volatile profile of the methanol extracts was evaluated by gas chromatography–mass spectrometry (GC–MS) obtaining mainly, terpenes, phenyl derivatives, and fatty acids.