Phenolic compounds and antioxidant properties of different grape cultivars grown in China

Skins and seeds of 18 grape cultivars belonging to Oriental and North American Vitis Species/hybrids, and Vitis vinifera were analysed for health beneficial properties. Four phenolic compound parameters (total phenols, flavonoids, flavan-3-ols and anthocyanins) and three antioxidant property parameters (DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, ABTS [2,2-azino-di-(3-ethylbenzothialozine-sulphonic acid)] radical scavenging and FRAP (ferric reducing antioxidant power)) were measured. Principal component analysis (PCA) was used for this evaluation and results showed that both phenolic compounds and antioxidant properties in the seeds and skins varied among the cultivars investigated. V. vinifera “Cabernet Sauvignon” had the highest values of phenolic compounds and antioxidant properties in seeds followed by Muscadines, while the lowest appeared in the Oriental Vitis species. As expected, these values of the Euro-Asian or Euro-American hybrids fell between the parents. However, far less variation of these values was observed in the skins among different grape cultivars investigated. Interestingly, even the total phenolic contents in the berries of two cultivars are similar, distributions of phenolic compounds in seeds and skins varied greatly among them. Additionally, significant correlations among different antioxidant assays in both seeds and skins were observed. These antioxidant properties were also found highly correlated to the main phenolic compounds.