Antioxidant Activity and Phenolic Content of Seed, Skin and Pulp Parts of 22 Grape (Vitis vinifera L.) Cultivars (4 Common and 18 Registered or Candidate for Registration)

Abstract

Total phenolic contents and antioxidant activities of pulp, seed and skin of 22 grape varieties (7 white and 15 red) grown in the Marmara region of Turkey were determined (common, registered or candidate cultivars). The total phenolic contents of grape pulp, seed and skin parts ranged from 9.26 to 62.29, from 162.29 to 326.18 and from 96.61 to 167.42 mg gallic acid equivalents/100 g fresh weight, respectively. Seasonal changes were noticeable in the total phenolic contents and antioxidant activities of different grape parts. The antioxidant activity of grape seeds of registered or candidate cultivars was the highest, followed by skins and pulps. The antioxidant activities of grape skins were higher in red varieties than in white varieties. The results indicated that registered and candidate red or white grape cultivars may have high amounts of phenolics and possess a superior antioxidant activity in comparison to popular cultivars, such as Bilecik Irikarasi, Hamburg Misketi, Alfons and Isabella. Practical Applications Grapes are an important commercial commodity because they can be consumed fresh or processed into many food products such as juice, jams, raisins and wine. Chemical properties of grapevines are one of the most important factors that determine the industrial use of grape berries. A great deal of diverse phenolic compounds is located in the skins, pulp and seeds of grapes. The antioxidant activity of different parts of grapes has been studied in popular and hybrid varieties; however, studies should also be continued on hybrid varieties to determine better grape berries with high antioxidant activity and phenolic content. Berries with better quality in terms of antioxidant activity may present great potential for the food industry as well as health-conscious consumers.