The exploitation of bioactive compounds trom agri-food by-products has been
attracting an increasing interest from different industries within a circular economy
context since several of compounds may have health properties or be used as
natural colorants or preservatives. So far, several studies have been developed on
the characterization of red wine grape pomace and its components (seeds, skins,
and stems). However, less attention has been paid to other by-products, such as
grape pomace from white wine, the residues after distillation, wine lees, and
diatomaceous earth, the latter used in the filtration of wine and corresponding to
about 250 tons/year of waste in Portugal. In this work, samples of these by-products
were evaluated for their chemical composition by HPLC-DAD-ESI-Msn and
bioactivities (antioxidant activity by TBARS, DPPH, and reducing power assays, and
antimicrobial activity against eight bacteria and two fungi). Fifteen non-anthocyanin
phenolic compounds were found, including 5 phenolic acids, 4 flavan-3-0Is, 2 0-
glycosylated flavanols, 3 flavanol aglycones, and one unknown. In the red wine byproducts
12 anthocyanins were detected, most being malvidin derivatives. Wine
lees and white grape pomace before distillation presented the highest contents of
phenolic compounds. Ali samples showed antibacterial and antifunga! activity
against most of the tested microorganisms, with red and white grape pomace and
diatomaceous earth having the best bacteriostatic activity, while the lees stood out
against fungi. Ali samples showed promising antioxidant capacity, with very good
results obtained on TBARS for the white pomace after distillation and diatomaceous
earth. Overall, the results show that besides grape pomace other wine industry byproducts
are also good sources of bioactive compounds with high potential for
exploitation.To Campelo for the winemaking residues. To projecl "BacchusTech - Inlegrated Approach for
lhe Valorization of Winemaking Residues" (POCI-01-0247-FEDER-069583) and national
funds FCT/MCTES to CIMO (UIDB/00690/2020). L. Barros, M. Dias, S. Heleno Ihank FCT,
P.L, for Iheir scienlific employmenl program-contractinfo:eu-repo/semantics/publishedVersio
