Study of resveratrol and antioxidant activity in Georgian brand red wines and a number of foreign red wines.

Today wine pricing is guided by content of useful substances such as resveratrol and catechines. Resveratrol [3,4',5-trihydroxystilbene (RESV)] is a compound found in the skin of red grapes and is a constituent of red wine. Clinical investigation demonstrated that resveratrol lowers the levels of catecholamines, inhibits lipid peroxidation of low-density lipoprotein; it has anti-inflammatory, antioxidant activity etc. In Georgia the highest concentration of resveratrol has been reported in wines prepared from Saperavi grapes. Resveratrol contents and antioxidant activity of Georgian brand red wines made from Saperavi grape variety and of foreign red wines available on Georgian market were assessed and compared. It was found that resveratrol content distinguishes foreign wines, particularly the French wine from the Georgian brand red wines. The research showed that resveratrol content is higher in non-brand Kakhetian style Saperavi (6.24 mg/ml) than in European or other Georgian brand wines. Proportion of trans-resveratrol is higher in "Saperavi" by "Badagoni" (94.5%), French wine (93.83%) and Saperavi by "TbilGhvino" (93.49%). Given that trans-resveratrol is characterized by higher biological activity and medical importance than cis-resveratrol, their proportion may be an important criterion to measure healing properties of wine. In terms of antioxidant activity, Georgian wines are like foreign wines. It is concluded that Georgian brand wines with few exceptions are behind the foreign wines in several parameters. Since polyphenolic substances define wine price through their positive effects on human health, more detailed studies on polyphenolic content of Georgian wines are needed.