title: Nutrient retention and fate of iron-binding phenolic compounds during the injera processing of tannin-free and high-tannin sorghum.
abstract: BACKGROUND
  Traits such as bird-, insect- and mould-resistance are the focus in selecting improved sorghum varieties, but this often increases the tannin content, which can negatively affect iron bioavailability. The grain characteristics, nutrient retention, and the fate of iron-binding polyphenols (IBPs) during injera processing, an Ethiopian traditional fermented pancake, were investigated using agriculturally improved tannin-free (TFC) and high-tannin (HTC) sorghum cultivars.
  
  
  RESULTS
  The HTC had significantly higher IBP contents than the TFC (P < 0.05). Decortication led to iron (24-27%), calcium (18-43%), IBP (catechol 35-41%, galloyl 35-42%), and tannin (12-35%) losses. Sourdough fermentation reduced the IBP and tannin concentrations in HTC, but had no effect on the IBP concentrations in TFC. The modified injera processing that included pre-soaking resulted in the highest IBP reductions (galloyl 73% and catechol 71%).
  
  
  CONCLUSIONS
  Nutrient retention in HTC and TFC processing was different. Including a pre-soaking step during injera processing of HTC could counter the negative effects of IBP on iron absorption, while benefiting from the agronomic features of HTC.
authors.affiliation: College of Natural Sciences, Addis Ababa University, Center for Food Science and Nutrition, Ethiopia.
authors.forename: Yohannes
authors.initials: Y
authors.lastname: Seyoum
authors.affiliation: College of Natural Sciences, Addis Ababa University, Center for Food Science and Nutrition, Ethiopia.
authors.forename: Negussie
authors.initials: N
authors.lastname: Retta
authors.affiliation: College of Natural Sciences, Addis Ababa University, Center for Food Science and Nutrition, Ethiopia.
authors.forename: Kaleab
authors.initials: K
authors.lastname: Baye
mesh_terms: D001682:Biological Availability; D005285:Fermentation; D005511:Food Handling / Q000379:methods*; D007501:Iron / Q000378:metabolism* / Q000493:pharmacokinetics; D010636:Phenols / Q000032:analysis* / Q000378:metabolism; D059808:Polyphenols / Q000032:analysis / Q000378:metabolism; D045868:Sorghum / Q000737:chemistry*; D013634:Tannins / Q000032:analysis*
chemical_list: D010636:Phenols; D059808:Polyphenols; D013634:Tannins; D007501:Iron
keywords: calcium; decortication; injera; iron; polyphenols; sourdough fermentation