Investigation on phenolic and aroma compounds of table grapes from Romania

The chemical composition of Romanian table grape varieties was determined to evaluate their phenolic and aroma profiles because they are factors useful for the variety characterization and consumer acceptance. Two white table grapes ('Aromat de Iasi' and 'Timpuriu de Cluj') and two red table grapes ('Napoca' and 'Somesan') were studied. The phenolic composition of berry skins and seeds was determined using spectrophotometric methods. The profile of anthocyanins and hydroxycinnamoyl tartaric acids (HCTs), and the content of trans-resveratrol were determined in the skins using high-performance liquid chromatographic (HPLC) methods. Free volatile compounds were quantified by gas chromatography/mass spectrometry (GC/MS). A different phenolic and aromatic composition was found in the varieties studied. Among white grapes, 'Aromat de Iasi' stands out for the great number of aroma compounds, and 'Timpuriu de Cluj' showed high contents of polyphenols, particularly oligomeric flavanols in skins and seeds (1,171 and 1,189 mg kg-1, respectively) and total skin HCTs (181.6 mg kg-1). The red variety 'Napoca' had high contents of total anthocyanins (380 mg kg-1) and total skin HCTs (183.2 mg kg-1), and it is characterized by high percentages of acylated anthocyanin derivatives (28.5%) and trans-caffeoyltartaric acid forms (58.8%). 'Somesan' grapes showed high contents of free volatile compounds, particularly of 1-hexanol, (Z)-3-hexen-1-ol and (E)-2-hexenoic acid (167.0, 59.4 and 167.0 μg kg-1). These results may contribute to the knowledge of Romanian table grapes perspective and to a better exploitation of these varieties.