- Peer Reviewed Paper – Astringent sub-qualities elicited by red wine: the role of ethanol and pH Palmina DeMiglio , Gary J. Pickering*, and Andrew G. Reynolds Cool Climate Oenology and Viticulture Institute, Brock University, St. Catharines, L2S 3A1, Canada; * = corresponding author [email: gpickeri@brocku.ca] Abstract: The objectives of this study were to characterize the effects of pH and ethanol on the astringent sub- qualities of red wine. This was achieved using a de-alcoholized red wine, one portion of which was adjusted to pH values of 3.2, 3.4, 3.6 and 3.8, and another portion to ethanol concentrations of 0%, 6%, 12%, and 15% v/v. Four further treatments were adjusted to pH 3.4 or 3.6 and with ethanol concentrations of 12% or 15% v/v. The wines were assessed sensorially and seventeen terms were identified, through panel consensus, to describe the astringent/mouth-feel qualities: velvet, aggressive, silk/satin, dry, fleshy, unripe, pucker, viscosity, abrasive, heat, chewy, acidity, grippy/adhesive, bitter, balance, overall astringency, and mouth-coat. Flavour profiling techniques were used to train the panel and measure the intensity of these attributes. Ethanol and pH affected a number of these attributes. Decreasing pH values (averaged across all ethanol concentrations) gave an increase in the overall astringency of the wine. The combined treatments of ethanol and pH (pH 3.4 and 3.6; 12% and 15% ethanol) did not have an effect of the perception of the astringent sub-qualities of the wine. These findings have implications for how processing decisions, such as optimum grape maturity, may affect wine quality. Introduction : Astringency is often defined as a drying, roughing and puckering mouth-feel sensation (American Society for Testing and Materials, 1989) which increases in intensity upon repeated exposure (Guinard et al., 1986a). Mouth-feel refers to sensations, in the mouth that are mediated by the trigeminal nerve (Jackson, 1994). It also includes the tactile perception of foods or beverages From: DeMiglio, P., Pickering, G.J., and Reynolds, A.G. (2002). Astringent sub-qualities elicited by red wine: the role of ethanol and pH. IN Cullen, C.W., Pickering, G.J., and Phillips, R. (eds). Proceedings of the International Bacchus to The Future Conference, St Catharines, Ontario, May 23 rd – 25 th , 2002, 31-52 (ISBN: 0-9682851-1-2).