White Wines by Color imetr ic Assays

For evaluation of flavonoid phenols in the low concentration range in white table wines, four colorimetric assays have been compared: (a) reaction with Folin-Ciocalteu reagent before and after precipitation of flavonoids in HCI-methanal (FC); (b) reaction with vanillin (VAN); (c) reaction with 4-(dimethylamino)-cinnamaldehyde (DAC); and (d) a rapid browning test at 60°C in oxidative medium (POM). There was a highly positive correlation between concentration units obtained by FC, VAN, and DAC, while POM is poorly correlated to concentration units. VAN and, to a lesser extent, FC lead to an overestimation of flavonoid content. DAC displays highest sensitivity and reproducibility. It appears most suitable for appreciation of oxidative aging potential in routine control.