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Condensed Tannins in Traditional Wet-Cooked and Modern Extrusion-Cooked Sorghum Porridges

¹Cereal Quality Laboratory, Soil & Crop Sciences Department, Texas A&M University, College Station, TX 77843-2474. ²Department of Food Science, University of Pretoria, Pretoria 0002, South Africa. ³Department of Applied Biology and Biochemistry, National University of Science and Technology, Bulawayo, Zimbabwe. ⁴Present address: Council for Scientific and Industrial Research, P.O. Box 395, Pretoria, 0001, South Africa. ⁵Corresponding author. Phone: 979-845-2925. Fax: 979-845-0456. E-mail: lrooney@tamu.edu ⁶Deceased.

The profile and quantities of condensed tannins (CT) in foods are affected by processing due to their highly reactive nature, which may affect their antioxidant activity and the nutritional value of the foods. The objective was to compare the quantity and profile of condensed tannins in traditional wet-cooked and modern ready-to-eat extrusion-cooked sorghum porridges. CT were analyzed using normal-phase HPLC with fluorescence detection and their content was compared to CT and total phenols determined with standard colorimetric assays. Both the traditionally prepared and instant porridges had significantly reduced CT polymers (DP > 8), with retentions of 38 and 9%, respectively, of the CT present in the whole grain. Oligomer (DP 2–8) and monomer (DP 1) contents in traditional porridges were not significantly different from those of grain. In extruded porridges, the oligomers were reduced and the monomer content was increased. The extractable CT oligomers and monomers in the extrusion-cooked sorghum porridges may be more biologically available because extrusion appears to increase their availability.