Phytochemical Composition and Content of Red-Fleshed Grape Accessions

Red-fleshed grapes are important breeding resources, and study of the content and composition of phenolic compounds in red-fleshed grapes is lacking. In this study, the profiles of phenolic compounds in the whole berry, flesh, and peel of thirteen red-fleshed grape (Vitis) accessions were determined for two consecutive years. The content of total phenolic compounds ranged from 4.795 to 29.875 mg g(-1) FW (fresh weight) in berry, from 1.960 to 12.593 mg g(-1) FW in flesh, and from 17.067 to 60.182 mg g(-1) FW in peel. As expected, anthocyanins were the main phenolic compounds, accounting for 90.4, 89.4, and 94.1% of the total phenolic compounds in berry, flesh, and peel, respectively. Flavanols accounted for 36.2% of the non-anthocyanin phenolic compounds in berry, 35.3% in flesh, and 38.3% in peel. In comparison, flavonols accounted for about 11.6, 5.7, and 15.8% of the non-anthocyanin phenolic compounds in berry, flesh, and peel, respectively. Hydroxycinnamic derivatives were the most abundant non-anthocyanins and accounted for 53.8, 56.1, and 44.3% of non-anthocyanin phenolic compounds in these three tissues. The content of phenolic compounds in peel was significantly higher than that in flesh and whole berry. A significant variation in the content of total and individual phenolic compounds was observed among different red-fleshed grapes, suggesting that genetic background was an important factor affecting the accumulation of these phenolic compounds. This work represents the most comprehensive characterization of phenolic compounds profiles in red-fleshed grapes.