Acid and enzymatic hydrolysis of the residue from Castor Bean (Ricinus communis L.) oil extraction for ethanol production: Detoxification and biodiesel process integration

Abstract

The starch hydrolysis process of Castor Bean Cake by (CBC) acid or enzymatic combination of alpha-amylase, glucoamylase and pullulanase was evaluated and followed by fermentation. The chemical hydrolysis resulted in 27.3 g L-1 of sugars with 33.4% of hydrolysis efficiency. The generated hydrolyzate was fermented yielding 11 g L-1 of ethanol (Y P/S=0.48 g g-1). The best enzymatic hydrolysis condition was as follows (per gram of CBC): 200 μL of α-amylase, at 90 °C; 200 μL of glucoamylase and 100 μL of pullulanase, both at 60 °C, which yielded 75 g L-1 of total reducing sugars corresponding to 91.4 % of hydrolysis efficiency. These sugars were subsequently converted to 34.5 g L-1 of ethanol. The acid hydrolysis process was also capable to allow the detoxification of the Castor Bean Cake. ©2008 Sociedade Brasileira de Química.