Avaliação da produção de etanol a partir da fibra do caju pré-tratada em microondas

Abstract

Nowadays, there is great interest in exploring alternative energy sources to maintain the sustainable growth of society. Cashew apple bagasse, lignocellulosic by-product in Brazil with no commercial value, is obtained from cashew apple process to juice production. In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant structures of the cashew fiber is studied. Results showed that, after enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, being the best result achieved after pretreatment with 1.0 mol.L-1 of NaOH (73 ± 8 mg.g-1 CAB-M) when 2% (w/v) of CAB-M was used. On enzymatic hydrolysis step, improvement on solid percentage (16 % w/v) and enzyme loading (30 FPU.gFTP -1) increased glucose concentration to 15 g.L-1. The fermentation of hydrolyzate by Saccharomyces cerevesiae resulted in ethanol concentration and productivity of 7.20 g.L-1, and 1.44 g.L-1.h-1, respectively. The results demonstrate that microwave-assisted alkali pretreatment is able to remove recalcitrant structures of CAB and to improve its enzymatic digestibility.