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K. J. SIEBERT1, A. Maekawa, and P. Y. Lynn. (1) Food Science & Technology, Cornell Univ., New York State Agricultural Experiment Station, 630 W. North St., Geneva, NY 14456-1371 The astringency of polyphenols results from their combination with and precipitation of salivary proline-rich proteins (PRP), which reduces lubrication in the mouth. Acids have long been known to enhance polyphenol astringency and many acids in water have been described as astringent. It was recently shown that polyphenols are normally present in saliva and that reducing saliva pH intensifies PRP-polyphenol interaction. The interaction, as assessed by light scattering, is maximal near pH 4.4 and declines at both higher and lower pH. This interaction intensification appears to be responsible for the astringent sensation produced by acids. It may also be possible to demonstrate lower astringent sensations with higher acid concentration. The object of this study was to further investigate the possibility that acids intensify interactions between salivary PRPs and salivary polyphenols, resulting in increased astringent sensation. Sensory tests were carried out with HCl solutions of varying strength. Controlled volumes were administered to panelists who rated both astringency and sourness. A number of panelists consumed two cups of green tea per day and at various times contributed saliva samples for total polyphenol analysis via the Folin-Ciocalteu method. Most panelists found a sample other than the highest acid concentration to be the most astringent, but this did not achieve statistical significance. Consuming green tea led to markedly higher salivary polyphenol levels in all panelists. The time lag between initial tea consumption and the increase in saliva polyphenol content varied with individuals, as did the highest level achieved. It appears that the sensation of astringency produced by acids results from intensification of interactions between salivary polyphenols and salivary PRP. This accounts for the astringency sensation caused by acids whether or not polyphenols are present in a sample.
Session 97, Sensory Evaluation: Analytical testing
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