Non-cooking methods on bitter cassava (Manihot glaziovii) starch hydrolysis as initial process for bioethanol production

Abstract

Bioethanol is derived from vegetable raw materials through hydrolysis and fermentation processes. The conventional hydrolysis process requires high energy consumption and increases the slurry viscosity so that it can reduce the ethanol yield. The development of a non-cooking method for starch hydrolysis is considered as more efficient technology. The purpose of this study was to study the effect of substrate concentration (100, 200, 300 g/L) and enzyme concentration (0.5, 1, 1.5% w/w) on reducing sugar production and to study the effect of fermentation time on bioethanol production. The hydrolysis and fermentation processes were carried out for 18 and 78 hours, respectively. StargenTM 002 and Saccharomyces cerevisiae were also used in the hydrolysis and fermentation processes. The results showed that the use of a substrate concentration (200 g/L) along with 1.5% (w/w) enzyme induced the increase percentage of reducing sugar of 37.24%. The reducing sugar (41.94 g/L) was then fermented for 78 hours. The optimum time for bioethanol production (14.22% v/v) was 60 h and was constant up to 78 hours.