Differential Content of the Total Polyphenols and Flavonoids in Three Romanian White Grape Cultivars

Among 60 vining species growing almost exclusively in the Northern hemisphere, only the grapevine (Vitis vinifera L.) (Vitaceae) is the single species largely used in the global wine industry. Grapes are important sources of antioxidants, such as phenolic compounds. The antioxidant activity of these polyphenols is considered much higher than that of the essential vitamins, thus contributing significantly to the dietary benefits of grapes (1). In addition, phenolics are the most important fraction involved in quality parameters of wines. It has been reported that the unique mix of phe-nolic compounds has many biological activities, including cardioprotective, anti-inflammatory, anti-carcinogenic, antiviral and antibacterial properties attributed mainly to their antioxidant activity (2). The major components of grape skins and seeds include phenolic acids, flavonoids and stilbenes. These grape seed and skin constituents have been shown to have health functional activities (3). In this context, the main aim of this study is to investigate the content of total polyphenols and fla-vonoids in three grape cultivars from the Cotnari vineyard (Romania) and provide information about their accumulation in skin, pulps and seeds. Three samples of mature white grape cultivars (Grasă de Cotnari, Fetească and Tămâioasă) were collected from the Cotnari vineyard during harvesting period (vintage September, 2014). The components of grape cultivars (from three different plants) were dried at 60°C and measured until constant weight. The samples of grape berry seeds, skins and pulp were extracted with methanol; the supernatants were collected and used for extraction. Total poly-phenolics and flavonoids, in the selected extract samples were determined (4, 5). The content of total phenolics from methanolic extracts of grapes cultivars varies within seeds, skin and pulp components (Table 1). From all of these, the highest content of phenolics was recorded in seeds, in all three investigated cultivars; in pulps and skins, there are no significant differences among the three cultivars. However, for the skin of Tămâioasă cultivar, only a slight increase was detected, comparatively with skins and pulps of the two other cultivars. In the case of flavonoids, the same pattern was identified , as in the case of polyphenols accumulation. Thus, the highest content was recorded in the case of seeds, followed by skins and pulps, consequently. Within the three cultivars, no important differences were measured; Grasă de Cotnari shown a small increased value in terms of seeds, while Tămâioasă cul-tivar displayed a slight increase in skins and pulps. Overall, there was no considerable …