Ethanol production from castor bean cake (Ricinus communis L.) and evaluation of the lethality of the cake for mice

The castor bean cake is rich in starch (48 +/- 0.53%) and bears a problem linked to the occurrence of a toxic protein (ricin). The chemical hydrolysis (ratio solid:liquid = 1:6; H2SO4 = 0.1 mol L-1; 120 degrees C; 40 min) generated a medium with 27 g L-1 of reducing sugars (hydrolysis efficiency = 32%). The hydrolyzed product was fermented and produced 11 g L-1 of ethanol (volumetric productivity=1.38 g L-1 h(-1) and ethanol yield on substrate consumed=0.45 g g(-1)). In vivo experiments (DL50) revealed a reduction of roughly 240 times in the CBC toxicity (2.11 mu g g(-1)).