Study of Phenolic Compounds of Grape Pomace

Abstract

The article presents experimental data on the component composition of the phenolic complex of aqueous-alcoholic extracts of sweet and fermented pomace of Cabernet Sauvignon, Merlot, Saperavi, Krasnostop Anapskiy, Dostoyny and Alkor red grape varieties. In extracts of sweet pomace, the presence of various concentrations of flavones, anthocyanins, procyanidins, oxycinnamic and hydroxybenzoic acids has been revealed. Flavonoid monomers are represented by anthocyanins, quercetin, (+)-D-catechin, (-)-epicatechin. Monomers of non-flavonoids are represented by hydroxy acids - caftaric, cautaric, and gallic. As for oligomeric polyphenols, the presence of bВ₁, В₂, В₃, and В₅ procyanidins has been revealed.The presence of resveratrol stilbene has been registered as well. The greatest amount of most of the components of the phenolic complex, including resveratrol, was found in extracts from the Krasnostop Anapsky and Saperavi grape varieties, while the smallest amount was found in Merlot. In fermented pomace, the concentration of all groups of phenolic compounds, especially procyanidins and anthocyanins, was less than in sweet pomace, while the presence of myricetin, myricetin-3-glycoside, peonidin-3-O-(6'-acetyl-glycoside), and cyanidin-3.5-O-diglycoside malvidin- 3-O- (6'-p-coumaroyl glycoside) has not been registered. All extracts had antioxidant activity, the value of which depended on the grape variety and the technology for obtaining pomace. The highest value of antioxidant activity was registered in the extract of sweet pomace of KrasnostopAnapsky and Saperavi grape varieties.