A comparison of methods used to define the phenolic content and antioxidant activity of Croatian wines.

摘要

The concentrations of phenolic antioxidants and antioxidant activities were determined for 3 different vintages of red varietal Plavac mali wines (Grgich), white varietal Posip wines (Grgich) and white varietal Zlahtina wines (Grskovic). Two different tests, the spectrophotometric Folin-Ciocalteau and redox derivative potentiometric titration with electrogenerated chlorine, were used to quantify phenolic antioxidants and express them in gallic acid equivalents. Of the wines tested, Plavac mali (2003 vintage) showed the highest phenol contents (~5 g/litre). All six white wines showed approximately ten-times lower phenolic levels than red wines (190-380 mg/litre), as they do not contain anthocyanins and other pigments. The change in the free radical scavenging ability of the same set of wines was evaluated according to the Brand-Williams assay. Red wines showed higher free radical scavenging ability (by 8-times) than white wines. The free radical scavenging ability of white wines decreased with time (older vintage), whereas that of red wines increased due to the formation of condensed tannins..