Ethanol Production From Onggok Using Crude Extract of Alfa Amylase, Glucoamylase and Saccharomyces cerevisiae

• Main Author: Rosita
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/34839
• Institution: Institut Teknologi Bandung

Bioethanol is an alternative fuel premium mixture because it can save fuel utilization and reduce air pollution. Bioethanol is made from biomass containing sugar, starch, and cellulose. Onggok is a byproduct from tapioca flour processing industry which contains 60-70% starch and is a potential bioethanol raw material. This research was aimed to use onggok as bioethanol raw material using crude extract of alpha amylase and glucoamylase from Aspergillus niger, Aspergillus oryzae, and Rhizophus oryzae in saccarification process and alcohol fermentation by Saccharomyces cerevisiae. Substrate optimization on crude enzyme production was aimed to determine the optimum substrate to produce enzyme with the optimum activity of alpha amylase and glucoamylase. The media compositions that was used in the crude enzyme production were rice bran, onggok, and basal medium with composition (1) 100 % rice bran, (2)100% rice bran with basal medium, (3)100% onggok with basal medium and (4) 90% rice bran with the 10% onggok and basal medium. The highest activity of alpha amylase crude enzyme was obtained from A. oryzae on day 2 with 385,14 U/mL, the second was A.niger with activity of 373,14 U/ml on day 2 on 100%:rice bran and basal medium, third R.oryzae with glucoamylase activity of 363,45 U/ml on day 5 with medium composition of 90% rice bran : 10% onggok with basal medium. Based on these result, the medium composition of 90% rice bran : 10% onggok : basal medium and medium composition 100% rice bran with basal medium were not significantly different (p>0,05) in producing alpha amylase crude enzyme and the activity of alpha amylase from A. niger and A.oryzae were not significantly different (p>0,05). The highest activity of glucoamylase was obtained from R.oryzae on day 3 with activity 479,02 U/mL using medium composition 90% rice brand: 10%onggok and basal medium. The second highest activity of glucoamylase was A.niger with 230,79 U/mL using 100% onggok basal medium, and the third was A.oryzae of 222,65 U/ml on day 9 using 100% onggok with basal medium. Based on the result all optimization medium to produce of glucoamylase enzyme were significantly different (p<0,05) and the activity of glucoamylase of A.niger, A.oryzae, and R.oryzae were significantly different (p<0,05). The next step was the optimization of saccharification on onggok substrate using crude extract of A. oryzae alpha amylase and R. oryzae glucoamylase. This optimization was aimed to determine the optimum saccarification time length which produced the lowest starch concentration by alpha amylase activity and the highest reduction sugar by glucoamylase activity. Based on the result, the optimum time of A.oryzae alpha amylase crude extract was obtained on the 27th hour with 11,4% of starch reduction, while R.oryzae glucoamylase crude extract was obtained on the 15th hour and produced 21,58 mg/mL of reduction sugar with 6,47% of saccharification efficiency. When glucoamylase of R.oryzae used on 27th hour after alpha amylase of A.oryzae, on 36th hour was produced 139,20 mg/mL of reduction sugar with 41,77% of saccarification efficiency. The next step was the solid alcoholic fermentation of sugar from onggok hydrolysis with Saccharomyces cerevisiae for 5 days. The highest ethanol was obtained on day 4 (7,89% v/v) with 6,6 % v/v/day of day rate. On this step, 87,5% of reduction sugar was converted in ethanol.