Whole Lyophilized
Olives as Sources of Unexpectedly
High Amounts of Secoiridoids: The Case of Three Tuscan Cultivars
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Abstract
The
phenolic profiles of three typical Tuscan olive cultivars,
Frantoio, Moraiolo, and Leccino, stored in different conditions (fresh,
frozen, and whole lyophilized fruits), have been compared during the
ripening period. Our main goals were to evaluate the phenolic content
of whole freeze-dried fruits and to test the stability of the corresponding
cake in oxidative-stress conditions. The comparison of fresh and whole
freeze-dried fruits from the 2012 season gave unexpected results;
e.g., oleuropein in lyophilized fruits was up to 20 times higher than
in fresh olives with values up to 80.3 g/kg. Over time we noted that
the olive pastes obtained from lyophilized olives contained highly
stable phenolic compounds, even under strong oxidative stress conditions.
Finally, it was also observed that the cake/powder obtained from unripe
freeze-dried olives was very poor in oil content and therefore quite
suitable for use in nutritional supplements rich in phenolic compounds,
such as secoiridoids, which are not widely present in the human diet