Protein binding and astringent taste of a polymeric procyanidin, 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose, castalagin, and grandinin.
The objective of the present investigation was to examine the oral astringency and protein-binding activity of four structurally well-defined tannins, namely, procyanidin [epicatechin16(4-->8)catechin], pentagalloyl glucose (1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose), castalagin, and grandinin, representing the three main structural categories of tannins, the proanthocyanidins, the gallotannins, and the ellagitannins. Astringency threshold and dos/response were determined by the half-tongue test using a trained human panel. Protein-binding stoichiometry and relative affinity were determined using radioiodinated bovine serum albumin in precipitation or competitive binding assays. Procyanidin and pentagalloyl glucose were perceived as highly astringent compounds and had relatively steep dose/response curves, but castalagin and grandinin had a lower mass threshold for detection. In vitro, procyanidin was the most effective protein-precipitating agent and grandinin the least. Increasing the temperature increased protein precipitation by the hydrolyzable tannins, especially grandinin. All four polyphenols had higher relative affinities for proline-rich proteins than for bovine serum albumin.
Hofmann
Thomas
T
Institut für Lebensmittelchemie, Corrensstrasse 45, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany.
Glabasnia
Arne
A
Schwarz
Bernd
B
Wisman
Kimberly N
KN
Gangwer
Kelly A
KA
Hagerman
Ann E
AE
D000328:Adult; D044946:Biflavonoids / Q000737:chemistry / Q000378:metabolism*; D001713:Biphenyl Compounds / Q000737:chemistry / Q000378:metabolism*; D002392:Catechin / Q000737:chemistry / Q000378:metabolism*; D002396:Catechols / Q000737:chemistry / Q000378:metabolism*; D011232:Chemical Precipitation; D004305:Dose-Response Relationship, Drug; D005260:Female; D006027:Glycosides / Q000737:chemistry / Q000378:metabolism*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D047348:Hydrolyzable Tannins / Q000737:chemistry / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008297:Male; D044945:Proanthocyanidins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013649:Taste
D044946:Biflavonoids; D001713:Biphenyl Compounds; D002396:Catechols; D006027:Glycosides; D006576:Heterocyclic Compounds, 4 or More Rings; D047348:Hydrolyzable Tannins; D007457:Iodine Radioisotopes; D044945:Proanthocyanidins; C479598:grandinin; D012710:Serum Albumin, Bovine; C084709:vescalagin; C435084:pentagalloylglucose; C017674:procyanidin; D002392:Catechin