Solvent free microwave extraction of Elletaria cardamomum L.: A multivariate study of a new technique for the extraction of essential oil

The solvent-free microwave extraction (SFME) of cardamom essential oil (Elletaria cardamomum L.) was studied. A multivariate study based on a central composite design (CCD) was used to evaluate the influence of three major variables affecting the performance of the solvent-free microwave extraction of cardamom seed. The yield and the composition of the essential oils from the dry cardamom seeds obtained by SFME were determined, and compared with those obtained by the traditional hydro-distillation (HD). Statistical treatment of the results provided by the CCD revealed that the selected parameters: extraction time, irradiation power and moisture content of the seeds were significant. The essential oils were analysed by gas chromatography–mass spectrometry (GC–MS). Essential oils provided by SFME are dominated by the oxygenated fraction which is the more valuable and composed of highly odoriferous aromatic compounds. Cardamom seeds treated by SFME and HD were observed by scanning electronic microscopy (SEM). Micrographs provide more evidence of the destruction of cardamom seeds treated by SFME, in contrast to conventional hydro-distillation.