Optimization of bioconversion of cassava to sugar for bioethanol production

Abstract

Cassava is one of the potential raw materials for bioethanol industry. Two steps involved in the starch hydrolysis are liquefaction and saccharification. The susceptibility of enzyme for hydrolysis was studied. Two enzymes were used in this study, which are alpha amylase (BAN 480L) and amyloglucosidase (AMG 300) for liquefaction and saccharification. Among various concentration of starch (15-40 % w/v) tried for maximum liquefaction; slurry made with 35% substrate concentration proved optimal. Liquefaction in shaking water bath at 85 °C, 20 min, pH7 and 0.30%( v/w) alpha amylase was an optimum condition for the liquefaction. The conditions for the saccharification of liquefied starch were optimized to be 60°C. pH 5. 0.25% (v/w) amyloglucosidase producing 2.71mg/ml glucose in 60 min. Supplementation of divalent ions Ca2+ and Mg2+ in the liquefaction and saccharification showed no effect. Finally glucose was found to be the main hydrolysis product of cassava starch.