3.2.3 Squalene and Sterols
The contents of squalene and sterols were illustrated in Table 3.
According to the literature, the content of squalene in olive oils
ranged from 1100 mg/kg to 8390 mg/kg (Beltrán et al., 2016). The
contents were higher than previously reported in both varieties (Salvo
et al., 2017). Significant differences were found in the contents of
squalene between varieties and tree ages. Koroneiki oils contained
notably higher squalene than Coratina oils. The amount of squalene was
changed along with the growth of the age depending on variety, first
decreased and then increased in Coratina oils while first increased and
then decreased in Koroneiki oils. The highest content of squalene was
present in 7-year-old Koroneiki oil and 7-year-old Coratina oil was the
one with the least squalene. The influences of varieties and tree ages
on the content of sterols were generally smaller than on squalene.
Squalene is considered as a precursor of sterols and triterpenoids. The
less amount of squalene signified that more squalene has been converted
to other phytomolecules.
The mean content of sterols in Coratina oils was 1174 mg/kg, a little
higher than that in Koroneiki oils. The variation of the content of
total sterols with tree age was in the opposite with the change of
squalene. The content of sterols first increased and then decreased in
Coratina oils while first decreased and then increased in Koroneiki
oils. In comparison with the same varieties from other countries, the
contents of total sterols were at or just below the average in the
present study (Aparicio and Luna, 2002). But the contents of total
sterols in all samples still reached the standard requirement
(> 1000 mg/kg) for EVOO. The result squared with the
theory, as the increased sterols may derive from squalene.