The recovery of raw materials offers an opportunity for
applying
the principles of circular bioeconomy. The phenolic composition of
three underused wine byproducts (skin, seed, and bunch stem) was analyzed
through UHPLC-QqQ-MS/MS to evaluate the intercultivar variability
comparing red and white grape cultivars from La Rioja (Spain) and
the influence of the winemaking, comparing conventional fermentation
and carbonic maceration. We observed that the red skin, especially
from Graciano, is rich in anthocyanins, whereas the white skin contains
mainly phenolic acids, flavonols, and flavan-3-ols, with Maturana
Blanca being the richest variety. Seeds are rich in flavan-3-ols and
lignans with Maturana Blanca and Viura, respectively, the richest
cultivars. Stems contain high amounts of flavan-3-ols, lignans, and
stilbenes, with the red cultivars of Garnacha and Tempranillo being
the richest samples. Carbonic maceration has a negative effect on
the phenolic amount compared to conventional fermentation. In synthesis,
we observed that each type of byproduct from red or white grape cultivars
has a particular phenolic composition that can result in obtaining
different ingredients with particular phenolic composition for target
applications.