Bioactive compounds derived from plants are secondary metabolites that can act through
various bioactivities, namely as antioxidant, antimicrobial, anti-inflammatory, anti-hypertensive,
and hypoglycemic agents. Combined with the pressure generated by consumers for more natural
products with beneficial effects on health, these compounds may be suitable candidates to act as
preservatives in food products. For this purpose, the extraction process becomes essential for the
acquisition of a quality extract with efficiency and with the desired final properties. Therefore,
the main objective of this work was to perform the optimization of the extraction yield of olive
leaves (Olea europaea L.), by applying response surface methodology (RSM) and employing dynamic
maceration as extraction technique. Three factors were analyzed: time (F1), temperature (F2), and
solvent (F3), ranging from 5 to 120 min, 25 to 100 C, and from 0 to 100% ethanol, respectively. The
study used the Box Behnken design, relying on 17 individual randomized runs. The response was the
dry weight of the extract (Y1), which ranged from 21.1 to 90.5 mg. The optimization studies pointed
to the increase of yield with the increase of time and temperature, but inversely by applying higher
time and lower temperature values and higher temperature and lower time values. The highest yield
of the dry extract was achieved at 120 min (F1), 25 C (F2), and 87% (F3) of ethanol:water. Future
studies will be carried out to analyze the preservative effects of incorporating olive extract in foods,
as well as analysis of other response for optimizing the best food preserving extract.
The authors are grateful to the Foundation for Science and Technology (FCT,
Portugal) for financial support through national funds FCT/MCTES to the CIMO (UIDB/00690/2020).
Acknowledgments to the Project financed by the European Fund for Regional Development (Fundo
Europeu de Desenvolvimento Regional (FEDER)) through the Programa Operacional Regional
Norte 2020, within the “PlantCovid” project, NORTE-01-02B7-FEDER-054870. M.C. Pedrosa thanks
“PlantCovid” project for her scholarship. S. Heleno and M. Carocho thank FCT for their individual
employment program-contract (CEECIND/00831/2018, CEECIND/03040/2017). L. Barros also
thanks the national funding by FCT, through the institutional scientific employment program-contract
for her contract.
This research was funded by the Foundation for Science and Technology (FCT, Portugal)
and the European Fund for Regional Development (Fundo Europeu de Desenvolvimento Regional
(FEDER)) through the Programa Operacional Regional Norte 2020, within the “PlantCovid” project
(NORTE-01-02B7-FEDER-054870). The authors are grateful to the Foundation for Science and Technology (FCT,
Portugal) for financial support through national funds FCT/MCTES to the CIMO (UIDB/00690/2020).
Acknowledgments to the Project financed by the European Fund for Regional Development (Fundo
Europeu de Desenvolvimento Regional (FEDER)) through the Programa Operacional Regional
Norte 2020, within the “PlantCovid” project, NORTE-01-02B7-FEDER-054870. M.C. Pedrosa thanks
“PlantCovid” project for her scholarship. S. Heleno and M. Carocho thank FCT for their individual
employment program-contract (CEECIND/00831/2018, CEECIND/03040/2017). L. Barros also
thanks the national funding by FCT, through the institutional scientific employment program-contract
for her contract.
