Adetunji, Adeoluwa IyiadeDuodu, Kwaku GyebiTaylor, J.R.N. (John Reginald Nuttall)2015-03-232015-03-232015-05Adetunji, AI, Duodu, KG & Taylor, JRN 2015, 'Inactivation of tannins in milled sorghum grain through steeping in dilute NaOH solution', Food Chemistry, vol. 175, pp. 225-232.0308-8146 (print)1873-7072 (online)10.1016/j.foodchem.2014.11.102http://hdl.handle.net/2263/44099Steeping milled sorghum in up to 0.4% NaOH was investigated as a method of tannin inactivation. NaOH steeping substantially reduced assayable total phenols and tannins in both Type III and Type II sorghums and with Type III sorghum caused a 60–80% reduction in a-amylase inhibition compared to a 20% reduction by water steeping. NaOH treatment also reduced starch liquefaction time and increased free amino nitrogen. Type II tannin sorghum did not inhibit a-amylase and consequently the NaOH treatment had no effect. HPLC and LC–MS of the tannin extracts indicated a general trend of increasing proanthocyanidin/ procyanidin size with increasing NaOH concentration and steeping time, coupled with a reduction in total area of peaks resolved. These show that the NaOH treatment forms highly polymerised tannin compounds, too large to assay and to interact with the a-amylase. NaOH pre-treatment of Type III sorghums could enable their utilisation in bioethanol production.en© 2014 Elsevier Ltd. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Food Chemistry. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Food Chemistry, vol. 175, pp. 225-232, 2015. doi : 10.1016/j.foodchem.2014.11.102.BioethanolAlpha-amylase inhibitionNaOH steepingMilled tannin sorghumTannin inactivationPostprint Article