title: Variability in tannin content, chemistry and activity in a diverse group of tannin containing sorghum cultivars.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: USDA-ARS CGAHR, Manhattan, KS 66502, USA.
authors.forename: Rhett C
authors.initials: RC
authors.lastname: Kaufman
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Herald
authors.forename: Scott R
authors.initials: SR
authors.lastname: Bean
authors.forename: Jeff D
authors.initials: JD
authors.lastname: Wilson
authors.forename: Mitch R
authors.initials: MR
authors.lastname: Tuinstra
mesh_terms: D000963:Antimetabolites / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D055598:Chemical Phenomena; D018556:Crops, Agricultural / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000032:analysis / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion; D056625:Endosperm / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D005433:Flour / Q000032:analysis*; D007615:Kansas; D055595:Mechanical Phenomena; D008970:Molecular Weight; D010434:Pepsin A / Q000037:antagonists & inhibitors / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D059748:Proteolysis; D012639:Seeds / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism; D045868:Sorghum / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism; D013045:Species Specificity; D013499:Surface Properties; D013634:Tannins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism
chemical_list: D000963:Antimetabolites; D000975:Antioxidants; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D010940:Plant Proteins; D013634:Tannins; D010434:Pepsin A