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

Abstract

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.

Efficacy of Various Palate Cleansers with Representative Foods

“…The apparent discrepancy in findings is likely due to the difference in stimuli used. It is possible that the tea of the current investigation was less astringent than the wines used by Colonna et al (2004) and Ross et al (2007) and that the relatively lower level of astringency created a type of ceiling effect, making it impossible to differentiate the relative effectiveness of pectin solution, spring water, and table water crackers reported in the other investigations.…”

“…The current investigation found that pectin solution, spring water, and table water crackers were all equally effective at preventing changes across replicates for tea. In contrast, Colonna et al (2004) found that for red wine a pectin solution reduced astringency more effectively than crackers or water and that crackers were more effective than water. Similarly, Ross et al (2007) reported that crackers were more effective than a pectin solution and water at reducing perceived astringency of wine.…”

“…Both Pickering and Robert (2006) and Findlay et al (2007) used a pectin solution as a palate cleanser when testing astringent wines, and Colonna et al (2004) indicated that it was superior to water at reducing astringency buildup. The efficacy of a 5-g/l pectin solution was thus assessed, with 5 oz (∼148 ml) of the solution being served in 9-oz (∼266 ml) translucent plastic cups (Plastic Drinkware, Gordon Food Service, Columbus-Hilliard, OH, USA).…”

“…Ross et al (2007) conducted an investigation and found the unsalted crackers to be the most effective at reducing astringency buildup while water was the least effective. In other studies, the findings of Colonna et al (2004) and Brannan et al (2001) suggested that pectin and CMC solutions were the most effective palate cleansers for astringent stimuli.…”

Charge related astringency of chitosans

“…Three samples were evaluated during each session using the Williams Latin Squares method to reduce carryover effects (Schlich, 1993). After each sample, panelists went through the following rinse protocol to reduce carryover: a sip of water, a CMC rinse (0.55% w/w CMC), a bite of cracker (Ross, Hinken, & Weller, 2007), then and finally a sip of water (Brannan, Setser, & Kemp, 2001;Colonna, Adams, & Noble, 2004). …”