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Variability in tannin content, chemistry and activity in a diverse group of tannin containing sorghum cultivars†
Article first published online: 25 SEP 2012
Published 2012. This article is a U.S. Government work and is in the public domain in the USA
Journal of the Science of Food and Agriculture
Volume 93, Issue 5, pages 1233–1241, 30 March 2013
How to Cite
Kaufman, R. C., Herald, T. J., Bean, S. R., Wilson, J. D. and Tuinstra, M. R. (2013), Variability in tannin content, chemistry and activity in a diverse group of tannin containing sorghum cultivars. J. Sci. Food Agric., 93: 1233–1241. doi: 10.1002/jsfa.5890
- Issue published online: 20 MAR 2013
- Article first published online: 25 SEP 2012
- Accepted manuscript online: 28 AUG 2012 05:58AM EST
- Manuscript Accepted: 28 AUG 2012
- Manuscript Revised: 18 JUN 2012
- Manuscript Received: 15 MAR 2012
- protein digestibility;
Tannins are large polyphenolic polymers and are known to bind proteins, limiting their digestibility, but are also excellent antioxidants. Numerous studies investigating the functional properties of sorghum tannin have been conducted by comparing grain samples from different sorghum lines without considering the other intrinsic characteristics of the grain. The purpose of this study was to remove the confounding intrinsic factors present in the endosperm so the effect of the tannins could be evaluated utilizing a unique decortication/reconstitution procedure.
The tannin content of the 14 cultivars tested ranged from 2.3 to 67.2 catechin equivalents. The bran fractions were studied for their impact on protein binding and antioxidant capacity. Protein digestibility by pepsin ranged from 8% to 58% at the highest tannin level addition. Protein binding ranged from 3.11 to 16.33 g blue bovine serum albumin kg−1 bran. Antioxidant capacity ranged from 81.33 to 1122.54 µmol Trolox equivalents g−1 bran. High-performance size-exclusion chromatography detailed molecular size distributions of the tannin polymers and relationship to tannin functionality.
The tannin content and composition play a significant role in determining tannin functionality. These differences will allow for selections of high-tannin sorghums with consideration of the biological activities of the tannins.