Comparison of procedures for reducing astringency carry‐over effects in evaluation of red wines

The intensity of astringency of red wine increases when a single wine is sipped repeatedly or during evaluation of several red wines in one session. The effectiveness of different rinses in reducing or preventing the build‐up of astringency was evaluated using time‐intensity (TI) methodology. Trained subjects continuously rated the intensity of an astringent red wine using a sip and spit protocol. Ten s after the wine was sipped, it was expectorated. Ten s later, a rinse was sipped, which was spat out after another 10 s. Judges rated until astringency was no longer perceived. Between wine‐rinse combinations, subjects rinsed twice with de‐ionised water for 20 s. Intensity ratings at maximum intensity and at 5 s intervals were extracted from the TI curves and subjected to analysis of variance. Pectin (1 g/L) reduced astringency more effectively than water, polyvinylpyrrolidone (PVP) (4 g/L), gelatin (6 g/L), or ovalbumin (4 g/L) (Experiment 1). Low (1g/L) and high (5 g/L) concentrations of pectin and a high (1 g/L) concentration of carboxymethylcellulose (CMC) decreased astringency significantly more than rinses of Polycose, (5 and 40 g/L), CMC (0.01 g/L) or water (Experiment 2). In a third Experiment, unsalted crackers were shown to be more effective in decreasing astringency than water, although the pectin (5 g/L) rinse was superior to crackers and water. For the inter‐stimulus rinse protocol to be most effective, it was found to be important to remove the residuals from each ‘rinse’ by extensive water rinses before tasting the next wine.