Identification and Quantification of Phenolic Compounds in Grapes

Grapes are a major source of phenolic compounds. Phenolic compounds play an important role in the quality of grapes and wines, and the antioxidant activity of grapes has been positively correlated with their phenolic composition. This work was focused on the identification of phenolic compounds in the fruit extracts of 'Norton', also known as 'Cynthiana' grapes (Vitis aestivalis). Identification and quantification were performed using high performance liquid chromatography-mass spectrometry (HPLC-MS TOF) with an electrospray ionization interface in negative mode ion. Detection was carried out at 280 and 320 nm. Cactechin, epicatechin, isoremnetin, siringic acid, caffeic acid, gallic acid, protocatechuic acid, miricetyn, hidroxybenzoic acid, quercetyn, stilbenes, such as resveratrol, pteroestibene, transpiceid, piceatannol and E-viniferin were identified in the extract, and caffeic acid, gallic acid, protocatechuic acid, miricetyn, hidroxybenzoic acid and quercetyn were also quantified. The major concentrations found were of epicatechin, caffeic acid and catechin, followed by protocatechuic acid, hidroxybenzoic acid, gallic miricetyn and quercetyn corresponding to 1.9065, 1.4506, 1.2131, 0.2424, 0.0835, 0.0529, 0.0297, 0.0030 ug/g dry weight, respectively.