The development of a biorefining strategy for the production of biofuel from sorghum milling waste

The potential of using sorghum milling waste for the development of a biorefining strategy for the production of bioethanol was investigated. Both red and white sorghum were processed using a traditional Nigerian wet-milling process to sorghum flour. The sorghum milling waste, sorghum bran, was hydrolysed using both enzymatic and dilute acid hydrolysis to produce a generable fermentation feedstock. The hydrolysates were subsequently investigated for fermentative biofuel production. Following a hydrolysis step, a medium containing ˜61 g/L glucose was obtained. Trace presence of inhibitors was detected in the hydrolysates and sufficient nitrogen content to support microorganism growth and bioethanol production. In test bioethanol production experiments using the sorghum milling waste derived hydrolysates only, 24.35 g/L bioethanol was produced by a yeast Kluyveromyces marxianus, equivalent to a yield of 0.15 g bioethanol per g of sorghum milling waste.