The Efficiency of Using Oil Palm Frond Hydrolysate from Enzymatic Hydrolysis in Bioethanol Production

Abstract

Present study aims to use oil palm frond (OPF) hydrolysate obtained from enzymatic hydrolysis as feedstock for ethanol production. Pretreated OPF was used in this study. Optimization of ethanol production was performed using central composite design of response surface methodology. TAPPI Standard Methods were used to analyze the chemical composition of the pretreated OPF. The results obtained indicated that the biomass contains 63.68% of cellulose, 21.92% of hemicellulose and 14.4% of lignin content. Enzymatic hydrolysis of pretreated OPF showed that the highest reducing sugar of 2444.6 µg/g was obtained when the biomass was hydrolysed using cellulase (40 U/g) and hemicellulase (10 U/g) for 150 min at 50 °C. The kinetic study indicated that the specific growth rate of S. cerevisiae HC10 during ethanol production was 0.034 h−1 with about 20.39 h of doubling time. The biomass yield coefficient and ethanol yield coefficient obtained were 0.1623 g cell/g sugar and 0.1191 g ethanol/g sugar, respectively. The highest ethanol yield was 79.4%. Fermentation profile for ethanol production demonstrated that the highest ethanol (7.23 g/L) was detected at 24 h of fermentation process. Under optimized conditions of inoculum, 30 mL; hydrolysate, 78.85 mL; pH, 4.50; and incubation time, 94.01 h, the highest ethanol yield was 13.79 g/L. The results obtained from this study proved that OPF hydrolysate obtained from enzymes hydrolysis has high potential to be used as feedstock for ethanol production.