Grapefruit flavedo (Citrus paradisi Macf.) was extracted by different
methods: hydrodistillation; and solvent extraction using pentane, etha
nol and supercritical carbon dioxide (SC-CO2) at two fluid densities.
The composition of the distillates and oleoresins were compared. Monot
erpene hydrocarbons decrease in SC-CO2 extracts at 87-90% with respect
to their quantity in pentane extracts (95%) and in hydrodistillates (
97%); these levels in monoterpene hydrocarbons were related to the lim
onene content, the most representative compound in grapefruit essence.
Sesquiterpenes, aldehydes, alcohols and esters increased their GC are
a percentage in SC-CO2 extract at a high density of the solvent, with
respect to the hydrodistillate and the pentane extract. Very interesti
ng was the high increase in nootkatone concentration in the SC-CO2 ext
racts; this grapefruit essence component was 4.72% in the extract at 8
MPa, and it was 5.19% in that at 25 MPa; the ketone was very low in t
he hydrodistillates (0.22-0.26%). The monoterpene hydrocarbon concentr
ations, expressed as g of component in 100 g of extract, showed a decr
ease in SC-CO2 oleoresins. Oxygenated, sesquiterpenes and particularly
nootkatone increase their amount in SC-CO2 extracts. (C) 1998 John Wi
ley & Sons, Ltd.