Attempts to detoxify sorghum bran hydrolysates for the production of itaconic acid from sorghum bran

High-value chemicals are produced mainly from the fractionation of fossil which contributes to global warming. A major hurdle toward the renewable production of these chemicals is the high cost of raw materials, usually simple sugars. This work thus investigates for the first time, the potential for the production of itaconic acid (IA) from sorghum bran, an abundant food processing waste. Pretreatment optimisation experiments indicated 5% solid loading rate was most efficient in sugar release. Dilute acid and enzymatic hydrolyses liberated up to 73.8 g/L of glucose converted by Aspergillus terreus DSM 826 for IA production by submerged fermentation. General inhibitors such as HMF and furfural were elucidated; while the individual and collective impact of inhibitors specific to sorghum bran, and itaconic acid fermentation were investigated in glucose medium. It was observed that high amounts of tannin inhibited IA yield by up to 94.375% while sodium sulphate was found to be beneficial to IA production. Attempts were made to remove the inhibitors in a step-wise manner, using chemical and electrophoretic separation. Relatively low IA yields were obtained, and this can be ascribed to the complex nature of the substrate, particularly since IA fermentation is sensitive to trace amounts of various substances. Yields of 3.63 ± 0.3 g/L were obtained by the addition of 0.1g of tannic acid to glucose medium while over 10 g/L were obtained from bran hydrolysates. Itaconic acid fermentation is thus feasible from sorghum bran hydrolysates; even though more work needs to be done to improve yields.