Phenolics content and antioxidant capacity of Chilean grapes cv. Pais and Cabernet Sauvignon

Grapes (Vitis vinifera L.) are a source of phenolics and exhibit a high antioxidant capacity. In this study, the total phenolics content and the antioxidant capacity of ground grapes, juice, and skin fractions of two varieties of red grapes widely produced in Chile (Cabernet Sauvignon and Pais) were analyzed and specific phenolics (caffeic acid, gallic acid, resveratrol and catechin) were determined. The total phenolics content and antioxidant capacity were higher in Cabernet Sauvignon grapes vs. Pais, mainly in the skin fraction. The predominant phenolic species in all grape fractions was catechin, except in the skin of Cabernet Sauvignon, where resveratrol prevailed. Phenolic acids were not detected in grape juices, probably due to the absence of skin. Significant high correlations between specific phenolics, total phenolics content and antioxidant capacity were observed. The study presents practical data on some relevant chemical characteristics of grape fractions that are associated to potential health benefits.