Concerning the effect of the temperature, our results showed
that the olive lipase activity decreases at temperatures lower and
higher of 35 C. Instead, the lipase of oil palm, a tropical plant, is
clearly less stable at temperatures below 35 C [31], whereas for
karanda fruit lipase the authors reported a temperature optimum
of 30 C and a heat stability [25]. According to Cruz et al. [7] and
Shimizu et al. [42], our results suggest that olive lipases may be
inactivated by a heat treatment or simply be less active during the
extraction phases (which easily determine a temperature above
40e45 C of the olive paste/emulsion) so that the lipase action has
a limited effect on triacylglycerol hydrolysis. Anyway, we did not
observe any effect on lipase activity after a storage of olive fruits at
45 C for 24 h (data not shown), whereas Shimizu et al. [42]
reported a reduction in TGA hydrolysis following the storage of
olive fruits at 40 C for up to three weeks.