Beer astringency assessed by time-intensity and quantitative descriptive analysis:: Influence of pH and accelerated aging

pH and oxygen are usually considered as the main factors influencing the organoleptic stability of beer. Polyphenols from malt and hop contribute to several characteristics of beer flavor, but their incidence on astringency is rarely mentioned. In this work, effects of pH (3.0 and 5.0) and accelerated aging (0 or 5 days at 40 degrees C with low or high level of oxygen in the bottle) on astringency were measured by two sensory analysis methods: quantitative descriptive analysis and time-intensity analysis. In addition, the polymerization degree of polyphenols was determined for the different samples in this study. Whatever the sensory technique used, a trained panel showing high repeatability identified pH as the only factor having a significant effect on astringency. Accelerated aging, even with high level of oxygen in the bottle, does not significantly modify perception of this sensation compared with the 4 degrees C-stored beer, probably because the variation of polymerization degree of polyphenols was not sufficient to be detected by the panelists. (C) 2005 Elsevier Ltd. All rights reserved.