Deacidiﬁcation of olive oil by countercurrent supercritical carbon dioxide
extraction: Experimental and thermodynamic modeling
, Andrés M. Hurtado-Benavides
, Guillermo Reglero
, Tiziana Fornari
, Elena Ibáñez
Francisco J. Señoráns
Sección Departamental Ciencias de la Alimentación, Facultad de Ciencias, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain
Facultad de Ingeniería Agroindustrial, Universidad de Nariño, Pasto, Colombia
Instituto de Fermentaciones Industriales, CSIC, Juan de la Cierva, 3, 28006 Madrid, Spain
Received 17 March 2008
Received in revised form 8 July 2008
Accepted 13 July 2008
Available online 19 July 2008
Supercritical ﬂuid extraction
Group contribution equation of state
Supercritical carbon dioxide was used as an extractive solvent to remove free fatty acids from cold-
pressed olive oil. Crude oil of different acidity content (from 0.5 to 4.0 wt%) was extracted in a packed
column at 313 K and pressures of 180, 234 and 250 bar. The group contribution equation of state was
employed to simulate the separation process, representing the oil as a simple pseudo-binary oleic
acid + triolein mixture. Despite the simple representation of oil composition to simulate the deacidiﬁca-
tion process, a satisfactory agreement between the experimental and calculated yields and acidity of raff-
inates was obtained. The thermodynamic model was employed to study a continuous countercurrent
multistage extraction process which yielded a rafﬁnate having acidity lower than 0.7 wt%, when crude
olive oil with different FFA content was processed.
Ó 2008 Elsevier Ltd. All rights reserved.
Olive oil is commercially obtained by cold-pressing processes.
Depending on biological, meteorological, agricultural factors or
processing conditions, the crude oil obtained contains different
amounts of free fatty acids (FFA). These substances are also suscep-
tible to oxidation, leading to rancidity and conferring an undesired
ﬂavor to the oil. Therefore, high amounts of FFA in the oil must be
absolutely avoided. Furthermore, the lower the FFA content in the
virgin olive oil, the higher is its commercial value. According to the
European Union regulations (the major world producer of olive
oil), cold-pressed olive oil with FFA content greater than 2.0%
(lampante olive oil) is not acceptable for human consumption,
and reﬁning or deacidiﬁcation is required prior to blending with
virgin olive oil. Additionally, high valued olive oil (extra virgin olive
oil) must contain less than 0.8% of FFA (European Council Regula-
tion No. 1513/2001).
Therefore, the deacidiﬁcation of crude olive oil is important not
only for consumer acceptance but also because it has the maxi-
mum economic impact on production. The removal of FFA from
crude oil is, therefore, a crucial step in olive oil production since
it predominantly determines the quality of the ﬁnal product. The
well-known adverse effects of chemical or physical reﬁning pro-
cesses on the oil quality reduce its market value (Bondioli et al.,
1992). New alternative deacidiﬁcation processes proposed are re-
esteriﬁcation, solvent extraction, biological deacidiﬁcation, mem-
brane technology and supercritical ﬂuid extraction (SFE). Each of
these alternatives has its own advantages and drawbacks (Bosle
and Subramanian, 2005).
SFE using carbon dioxide is a low temperature and a relatively
pollution free operation. Its high selectivity permits the removal
of FFA from the oil with minimum loss of neutral oil: triglycerides
and unsaponiﬁable matter (tocopherols, sterols and vitamins).
Thus, when this technique is applied, the deacidiﬁcation process
can be carried out without signiﬁcant loss in yield or the nutri-
tional properties (Brunetti et al., 1989).
Brunetti et al. (1989) have investigated the extraction of fatty
acids from fatty acid + triglyceride mixtures using supercritical
carbon dioxide (SC-CO
). Experiments were carried out on samples
with different FFA content (from 2.6 up to 20 wt%) at pressures of
20 and 30 MPa and temperatures of 313 and 333 K. Besides the
limitations concerned with the use of batch equipment, they con-
cluded that the SFE was particularly suitable for deacidiﬁcation of
olive oils with FFA content lower than 10%, since the selectivity
factor for fatty acid extraction increases as the concentration of
FFA in the crude oil decreases. On the other hand, Simoes and
Brunner (1996) evaluated the possibility of using SC-CO
ify olive oil using a commercial oil containing squalene (around
0.7 wt%), FFA (from 3 to 15 wt%) and triglycerides. Experimental
0260-8774/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
* Corresponding author.
E-mail address: elena@iﬁ.csic.es (E. Ibáñez).
Journal of Food Engineering 90 (2009) 463–470
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