Background and methodology:
Grapes and wine contain large amounts of phenolic compounds. Moderate wine consumption reduces the risk of coronary heart disease. Phenolic compounds present in red wines cause an increase in serum total antioxidant capacity, and thereby inhibit low-density lipoprotein (LDL) oxidation. Compared to conventionally grown grapes, organic grapes contain unadulterated phenol free from residues of chemical treatments. Among fruit grapes, must and pomace are a valuable source of phenolic antioxidants. This study compared the level of phenol content and antioxidant potential in organically grown grapes, pomace (the solid remains after grapes are pressed for juice), must (fresh-pressed grape juice), and wines.
Findings:
The total phenol content and its capacity to increase antioxidant activity (AOA) and inhibit LDL were highest in pomace, grape, and must, respectively. For wines, similar results were found in red wines made from Cabernet Sauvignon, Merlot, and Zinfadel, respectively. Taking into account the grape color, the total phenol content and the antioxidant potential was 46 percent or more for red wines and only 3 to 6 percent for white wines. The study found positive correlation between total phenol content and AOA.
Reference:
Yildirim, H. K., Akcay, Y. D., Guvenc, U., Altindisli, A., and Sozmen, E.Y. (2005). Antioxidant activities of organic grape, pomace, juice, must, wine and their correlation with phenolic content. International Journal of Food Science and Technology, 40(2): 133-142. Available on-line at: http://dx.doi.org/10.1111/j.1365-2621.2004.00921.x