Free and Conjugated Myricetin, Quercetin, and Kaempferol in Bulgarian Red Wines

The moderate consumption of red wines is associated with a reduced risk of coronary heart disease and cancer. It is well known that red wines are a rich source of flavonoids, especially of flavonols. The data on flavonol content in Bulgarian food and beverages are extremely rare. Eleven red wines traditionally consumed in Bulgaria were analyzed for free and conjugated flavonols: myricetin, quercetin, and kaempferol. They were determined before and after acid hydrolysis using RP-HPLC with UV detection. The results show that Gamza wines have very low flavonol level (<1.0–4.0 mg/L). The total flavonol content for Merlot wines was 5.3–13.9 mg/L; for Cabernet Sauvignon wines, 9.3–13 mg/L; and for the Mavrud wine 14.8 mg/L. The maximum flavonol content was found in Melnik wines (12.2–16.9 mg/L). The results were compared with data from other surveys and will be included in the National Database of Food Composition.