Production of glucose from cassava starch: Statistical approach

Abstract

Bioethanol is obtained from cassava through a process fermentation of glucose syrups, produced in two step enzymatic process: liquefaction and saccharification. Liquefaction is carried out with the enzyme a-amylase (BAN480L), which fragments the starch into regularly sized chains, resulting in dextrin, maltose, maltriose and maltopentose. The amyloglucosidase enzyme (AMG300) acts in the saccharification stage, in which glucose syrups are obtained from hydrolyzed starch. The work attempts to study and optimize liquefaction and saccharification process. Two factors (time and enzyme concentration) affecting in liquefaction process while four factors (time, enzyme concentration, pH and temperature) affecting in saccharification process based on the preliminary study. The performance of a- amylase in liquefaction was determined by dextrinizing activity (D.A.) while the performance of amyloglucosidase was based on glucose concentration. A two-level factorial was initially carried out. The statistical analysis showed that both time and enzyme concentration significantly affects in liquefaction process while for the saccharification process, pH and temperature gave a significant effect. Hence a detail study was carried out using central composite design (CCD) in response surface methodology (RSIvi) to get a highest production of glucose. The optimal condition for liquefaction for 35% cassava starch slurry was by using 0.35% a-amylase in sodium acetate buffer (pH 7) at 85°C for 12.5 min respectively. The optimal conditions for saccaharification were found to be at 65°C, pH 4.5, using 0.2% amyloglucosidase in 40 min respectively. A model adequacy was very satisfactory, as coefficient of determination were 0.9747 and 0.9795 for liquefaction and saccharification.