초록
The development of bioethanol production is being widely discussed both the development of methods and materials used. One of potential raw material for bioethanol production is white sorghum (Sorghum bicolor). It thrives in tropical countries and has fairly high starch content about 65%-71% typically. Thus, it can be used as raw material of bioethanol production. During this process, a simultaneous saccharification and fermentation reaction (SSF) produces more ethanol than conventional processes. The purpose of this study is to determine proper method for producing bioethanol from this raw material by comparing SSF reaction of NaOH-treated white sorghum seeds to untreated sorghum seeds. Beads biocatalyst was prepared by co-immobilization method of glucoamylase by the yeast (Saccharomyces cereviceae) in Na-Alginate 6%. They were varied with variable concentrations of yeast 5%, 7%, 9% and 25%, 35% of glucoamylase enzyme. The biocatalyst is more stable, producing more bioethanol and reducing contamination. The results indicated that white sorghum seeds with 0.1M NaOH treatment produced more bioethanol than untreated sorghum seeds using beads biocatalyst with concentration of yeast 9% and 35% of enzyme. Maximum production of ethanol was 11.48% with the value of K<SUB>m</SUB> and V<SUB>m</SUB> are -0.0014g/mL and 0.00245g/mL.hour respectively. By overnight soaking in 0.1M NaOH solution, the purity of the starch in the white sorghum seeds increased.