UP’s part of WP 2 The Whole Gory Story (but fortunately for all concerned in a very shortened form)

Extraction of sorghum with aqueous ethanol (70%) + sodium hydroxide and sodium metabisulphite yields pure kafirin Addition of Sodium Hydroxide improves the yield of kafirin, also makes it more soluble, less prone to gelation gives it better film forming properties No NaOHWith NaOH

Method for casting free-standing films with aqueous ethanol

A plasticiser combination of equal parts: Glycerol, Polyethylene glycol 400 and Lactic acid found to be satisfactory for making kafirin films Brittle filmPlasticised film

Glacial Acetic Acid, Lactic Acid and Aqueous Isopropanol identified as alternative food compatible solvents for kafirin

Extraction of sorghum with Glacial Acetic Acid after pre-soaking with Sodium Metabisulphite gives high yield of pure kafirin

Kafirin can be extracted from both white and red sorghum bran

Free-standing films can be made from kafirin extracted from sorghum bran

Tannic acid (a Hydrolysable Tannin) and Sorghum Tannin (Condensed Tannin) can cross-link with kafirin

SCT TA Kafirin films with modified properties can be made from kafirin cross-linked with tannic acid or with sorghum tannin Modified films have increased tensile stress and decreased tensile strain and oxygen permeability Water barrier properties unaffected

Kafirin films made with different levels of Glycerol, Polyethylene Glycol 400 and lactic acid Principal Component Analysis showed that the most effective Plasticisers for kafirin films are the Associated Moisture, Glycerol (G) and Polyethylene Glycol (PEG) Lactic Acid (LA) is an essential component of plasticised kafirin films, but probably as solvent rather than a plasticiser

Glucono delta-lactone (GDL) when present with lactic acid was found to have potential as a kafirin film plasticiser GDL (% relative to protein wt) Stress (N/mm 2 ) Strain (%)

Journal papers Emmambux, M.N. and Taylor, J.R.N Sorghum kafirin interaction with various phenolic compounds. J. Sci. Food Agric. 83: Da Silva, L.S. and Taylor, J.R.N Sorghum bran as a potential source of kafirin. Cereal Chemistry 81: Emmambux, M.N., Iannace, S. and Stading, M Cereal biopolymer films, coatings and other industrial products. Chemical Technology (1): Taylor, J., Taylor, J.R.N., Dutton, M.F. and De Kock, S Identification of kafirin film casting solvents. Food Chemistry (In press). Emmambux, M.N., Stading, M. and Taylor, J.R.N Sorghum kafirin film property modification with hydrolysable and condensed tannins. Journal of Cereal Science (In press) Da Silva, L.S. and Taylor, J.R.N Physical, mechanical and barrier properties of kafirin films from red and white sorghum milling fractions. Cereal Chemistry (In press) Gao, C., Taylor, J., Wellner, N., Byaruhanga, Y.B, Parker, M.L., Mills, C. and Belton, P.S. (2004). Effect of preparation conditions on protein secondary structure and biofilm formation of kafirin. Journal of Agricultural and Food Chemistry (In press)

Deliverables D4: Kafirin protein from sorghum bran, Report: Extraction of kafirin from red and white sorghum milling fractions. L S da Silva, December 2002 D5: Screening of food-compatible non-ethanol kafirin extraction methods. J Taylor, December D6: Casting of free-standing kafirin films and investigation into film preparation and film properties using food compatible non ethanol solvents. J Taylor December 2002 D16: Modified kafirin films (cross-linked, plasticised and combined cross-linked and plasticised) J Taylor, August 2004 D17: Sorghum kafirin film property modification with hydrolysable and condensed tannins. M N Emmambux, M Stading and J R N Taylor, August 2004 D21: The physical properties, including biodegradability of modified kafirin protein films. J Taylor, M N Emmambux, H van Eck, Y B Byaruhanga and J R N Taylor, August 2004 (actually part of WP3)

Exhibitions Sorghum Protein Films. Science at the World Summit on Sustainable Development, CSIR, Pretoria, August 2002 Sorghum and Sorghum Protein Biofilms. University of Pretoria Open Day, May Out of Africa: Sorghum the Sustainable Cereal. Royal Society Summer Science Exhibition, London, July 2003