Abstract:

In this paper, the skins of Centennial Seedless from four main table grape-producing areas in Yunnan province
were analyzed for chemical composition and antioxidant activities of polyphenols from grape skins were evaluated. The
experimental results showed that the basic chemical components of grape skins varied with growing environment. Dry
matter and total sugar contents of grape skins from Yuanmou region were significantly higher than those of grape skins
from four other regions, which may be related to the higher intensity of sunlight in Yuanmou. The lipids in grape skins had
a high content of unsaturated fatty acids. Arabinose, galactose, glucose, and galacturonic acid were the main monosaccharides in
grape skins. Their contents in the descending order were glucose > arabinose > galacturonic acid > galactose. Proanthocyanidin
and polyphenol contents in grape skins from four producing areas were significantly different with significantly higher levels in
Mile than in the other regions, which may be related to the lower elevations. Rutin and catechin were the main phenolic acids in
grape skins. The antioxidant activity of polyphenols-rich skin extracts of grapes from four producing regions were evaluated by
1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS＋·) radical scavenging capacity
and reducing power (FRAP) arrays, and it was shown that the polyphenols in grape skins had high antioxidant activity with IC50
values of 12.95–14.68, 8.63–11.11 and 29.35–34.60 μg/mL respectively.

Key words: grape skin, chemical components, antioxidant activity