EFFECTS OF VISCOSITY ON THE BITTERNESS AND ASTRINGENCY OF GRAPE SEED TANNIN

To examine the separate effects of viscosity and sweetness on astringe ncy, aqueous solutions of grape seed tannin (GST) were thickened with carboxymethyl cellulose (CMC) from 2 to 45 cP (experiment 1) or sweete ned with 0 to 1.8 g/L aspartame (experiment 2). Trained subjects conti nuously rated astringency and bitterness in duplicate. Subjects mere c ategorized by the salivary flow induced by citric acid and ability to taste n-propyl thiouracil (PROP). In experiment 1, maximum intensity a nd total duration of astringency were significantly decreased as visco sity rose, although time to maximum intensity of astringency was not a ffected. Maximum intensity and total duration of bitterness were not s ignificantly affected by increasing viscosity; however, the onset of b itterness was significantly delayed. In experiment 2, increasing sweet ness had no affect on any astringency parameter, although maximum inte nsity of bitterness was significantly decreased. Neither PROP nor sali vary flow-status had any effect on perception of bitterness or astring ency in either experiment. Copyright (C) 1996 Elsevier Science Ltd