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Influence of operation variables on quality parameters of olive husk oil extracted with CO 2 : Three‐step sequential extraction
Author(s) -
de Lucas A.,
Rincón J.,
Gracia I.
Publication year - 2003
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-003-0674-4
Subject(s) - extraction (chemistry) , chromatography , supercritical fluid , materials science , response surface methodology , pomace , yield (engineering) , fraction (chemistry) , supercritical fluid extraction , saponification , hexane , solvent , chemistry , mathematics , pulp and paper industry , metallurgy , food science , organic chemistry , engineering
Abstract Supercritical CO 2 extraction is a viable alternative process for the extraction of high‐quality oil from olive husk (also known as olive pomace), a residue obtained in the production of olive oil. We analyzed the effect of pressure (100–300 bar), temperature (40–60°C), solvent flow (1–1.5 L/min), and particle size (0.30–0.55 mm) on four important quality parameters of the oil extracted with CO 2 : tocopherol concentration, extinction coefficients at 232 and 270 nm, and saponification value. Response surface methodology was used to obtain mathematical expressions related to the operating variables and parameters studied. Results from these experiments were also used to design a three‐step sequential CO 2 extraction procedure to obtain a higher‐quality extract. The optimal operational sequence consisted of a first extraction step at 75 bar for 1 h using 1% (vol/vol) ethanol modifier, followed by a second extraction stage at 350 bar for 2.5 h without ethanol and a third step, also at 350 bar, for 2.5 h but using ethanol. These extraction conditions obtained an intermediate fraction of oil with 64% yield and all normal parameters according to European Commission food legislation. This fraction is suitable without any further refining. On the contrary, the oils obtained by hexane extraction and by conventional supercritical CO 2 extraction at optimal conditions are suitable for human consumption after further refining. This last finding may result in improved economics of the sequential CO 2 extraction process compared to the conventional extraction method with hexane.