SENSORY ASTRINGENCY OF 5-O-CAFFEOYLQUINIC ACID, TANNIC-ACID AND GRAPE-SEED TANNIN BY A TIME INTENSITY PROCEDURE

The astringency of 5-O-caffeoylquinic acid (5-CQA) was investigated by a time-intensity technique alongside those of tannic acid and grape-seed tannin. Significant differences were recorded between 5-CQA and the other phenolic solutions for the intensity of the response, its persistence (or overall duration), its fading (or decline from maximum intensity to zero), and for the total gustatory response (or total area under the time-intensity curve). In each case, 5-CQA elicited a weaker response than either grape-seed tannin or tannic acid. Nevertheless, overall, panellists recorded a response for 5-CQA that was qualitatively similar to those for tannic acid and grape-seed tannin, which are traditionally accepted as astringents. This phenomenon occurred, despite 5-CQA having a molecular mass of 354 and containing only one 1,2-dihydroxyphenyl residue, which would place it outwith the traditional definition of an astringent. The requirements appropriate to vegetable tanning may not therefore apply to oral astringency.