Sorghum as whole-crop feedstock for integrated production of fermentable sugars.

Abstract Fermentable sugar production from whole crop of three preselected varieties of sorghum was investigated. In addition to the free sugars in extracted juice, starch and cellulose found in grain and stalks (leaves) were enzymatically degraded to produce glucose using commercially available amylases and cellulases. Low temperature alkali pretreatment of the lignocellulosic residues was performed to improve the enzymatic digestibility of the biomass. Results showed that glucose yield from enzymatic hydrolysis of starch and cellulose reached 95% and 90%, with sugar concentration reaching 23% and 11% (w/v), respectively. Fermentable sugar and ethanol production potential of the three varieties was evaluated according to the experimental data in combination with the biomass yield data from the field experiment. Based on the present conversion platform, maximum ethanol yield in one crop cycle from the three varieties could reach 42.9, 75.4 and 76.9 L/a, respectively.