| dc.description.abstract | This project dealt with the acquisition of supercritical carbon dioxide (scG02) derived
extracts from Melissa officinalis. The actuality of such extracts lies in the diversity of its
components, which are relevant to the pharmaceutical, cosmetic, fragrance/flavour and
food industries.
Extractions were performed on selected dried plant material using a laboratory-scale
supercritical fluid extractor. The runs were executed according to an orthogonal, rotatable
statistical design in order to optimise conditions (pressure, temperature, duration) for a
maximum yield of extract by computer-assisted surface response analysis.
The relationship between the yield of extract and the principal process parameters enabled
conclusions to be drawn about the mechanism of extraction. The volatile components are
physically desorbed from the plant matrix as a result of the diffusivity of low-density (gas-like)
sc-CO2, whereas the non-volatile components are chemically dissolved on account of
the solvent strength of high-density (liquid-like) sc-CO2.
An equation based on a dimensionless grouping of variables was derived to mathematically
describe the extraction process in terms of all major contributing process parameters.
The extracts were analysed by GC/MS and GC-GC/TOF-MS. A total of 204 components
were identified, many of which correspond with those extracted by traditional methods and
which are reported in the literature.
The analytical results prove that component-rich botanical extracts can be obtained with sc-
CO2 as extractant. In addition, the fluid warrants solvent free extracts and clean technology
for sustained environmental protection. | |
