Cereal Chem 56:310 - 313.  |  VIEW ARTICLE
Grain Sorghum Condensed Tannins. I. Isolation, Estimation, and Selective Adsorption by Starch.

A. B. Davis and R. C. Hoseney. Copyright 1979 by the American Association of Cereal Chemists, Inc. 

The biologically active condensed tannins and other polyphenolics were extracted from bird-resistant grain sorghum and methyl alcohol after preextraction of the whole grain with water-saturated butanol. The condensed tannins were separated from other polyphenolics with Sephadex LH-20; the polyphenolics were eluted with 95% ethyl alcohol and then the condensed tannins were eluted with 50% acetone. A nonbird- resistant sample gave no condensed tannins by the above procedure. The phadebas alpha-amylase procedure used in conjunction with procine pancreatic alpha-amylase provided a simple, rapid, and reliable method for determinging the biologically active condensed tannins in both ground grain samples and extracted materials. The three varieties of bird-resistant grain sorghum differed little in terms of inhibition per unit weight of isolated condensed tannins. Condensed tannins isolated from three varieties of bird-resistant grain sorghum were absorbed by starch. The amount of tannins bound by starch varied both with the source of tannins and with the starch species. Data suggested the presence of at least two fractions in condensed tannins of grain sorghum; an alpha-amylase inhibiting fraction, which was absorbed on starch, and an inhibiting fraction, which was not absorbed on starch.