Enhanced enzymatic hydrolysis and ethanol production from cashew apple bagasse pretreated with alkaline hydrogen peroxide

Abstract

The effect of combinations and ratios between different enzymes has been investigated in order to assess the optimal conditions for hydrolysis of cashew apple bagasse pretreated with alkaline hydrogen peroxide (the solids named CAB-AHP). The separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes were evaluated in the ethanol production. The enzymatic hydrolysis conducted with cellulase complex and β-glucosidase in a ratio of 0.61:0.39, enzyme loading of 30FPU/gCAB-AHP and 66CBU/gCAB-AHP, respectively, using 4% cellulose from CAB-AHP, turned out to be the most effective conditions, with glucose and xylose yields of 511.68mg/gCAB-AHP and 237.8mg/gCAB-AHP, respectively. Fermentation of the pure hydrolysate by Kluyveromyces marxianus ATCC 36907 led to an ethanol yield of 61.8kg/tonCAB, corresponding to 15g/L ethanol and productivity of 3.75g/(Lh). The ethanol production obtained for SSF process using K. marxianus ATCC 36907 was 18g/L corresponding to 80% yield and 74.2kg/tonCAB.