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).
M.C. Pedrosa and F. Fernandes thank FCT for their PhD grants
(2021.04531.BD, SFRH/BD/145467/2019), S. Heleno and
M. Carocho thank FCT for their individual employment
program-contract (CEECIND/03040/2017, CEECIND/00831/2018), and L. Barros, M. I. Dias, and R. Calhelha also thank
FCT through the institutional scientific employment programcontract
for her contract.
The plant kingdom is an endless source of molecules that can be applied in almost all realms of society.
The food industry has profited from the use of plants and their derived materials for many decades.
Recently, the food industry has been looking into plants to find different ways of either preserving, coloring
or sweetening foods. In this work, leaf extracts of Arbutus unedo L. obtained by dynamic maceration
and ultrasound assisted extraction with prior optimization of their extraction conditions through the
response-surface methodology, were incorporated in quark cheese as natural preservatives and analyzed
over 8 days of shelf-life. Both extracts showed antioxidant activity with no toxicity towards primary cell
lines at the maximum tested concentration, as well as antibacterial activity, especially against Gram-positive
strains. After their incorporation in quark cheese, no significant changes were observed in the nutritional
profile and physical traits of the quark cheeses, while the microbial load was highly reduced in the
cheese, especially using the extracts obtained from dynamic maceration. Thus, leaf extracts of A. unedo
can be promising candidates for use in the food industry as natural preservatives.
