Influence of winemaking techniques on the resveratrol content, total phenolic content and antioxidant potential of red wines

In this paper, the influence of winemaking techniques and cultivars on the resveratrol content, total phenolic content and antioxidant potential of red wines was studied. Wines were made from the cultivars Merlot, Cabernet Sauvignon, Pinot Noir and Prokupac. Applied winemaking technologies included thermovinification and separation of must from pomace. The analysis of trans- and cis-resveratrol in wines was performed by HPLC, while the total phenolic content and antioxidant potential was determined by spectrophotometric methods. The total resveratrol content in analysed samples ranged from 0.35 to 4.85 mg/l; Merlot wines had the highest average resveratrol content, while the lowest was found for native cultivar Prokupac. Although the resveratrol content depended on grape variety, correlation between the winemaking technology applied and the resveratrol level in wines was not observed. The total phenolic content (TPC) varied from 544.4 to 1410.4 mg/l expressed as gallic acid equivalents, and the antioxidant potential, assayed by DPPH in terms of SC50 (mean scavenging concentration), ranged from 0.58 to 2.91 μl/ml. Obtained results showed that thermovinificated wine samples had higher amount of phenolic compounds. Significant negative correlation was observed (p < 0.05) between the total phenolic content and SC50, but there was no significant correlation (p > 0.05) between the resveratrol content and SC50 or TPC. This study could contribute to the establishment of optimal conditions for producing red wines which contain more beneficial phenolic compounds.