The effect of adding NaOH and fermentation time on Robusta coffee husk (Coffea canephora) bioethanol production with SSF (Simultaneous Sachraffication and Fermentation) method

Robusta coffee husk is one of the largest agricultural wastes and contains lignocellulose as a raw material for bioethanol production. Lignin in Robusta coffee husk can interfere with the enzymatic hydrolysis process, so a delignification process using NaOH solution is needed to remove it. This research aimed to determine the effect of adding NaOH and fermentation time on the bioethanol production from Robusta coffee husks using the SSF (Simultaneous Saccharification and Fermentation) method. Removal of lignin using NaOH with various concentrations of 6, 8, and 10% and fermentation time for 24, 48, 72, 96, and 120 hours. The cellulose, hemicellulose, and lignin contents in the delignification results were tested using the Chesson method. The saccharification and fermentation steps used cellulase enzymes and Saccharomyces cerevisiae. Bioethanol levels were analyzed using GCMS. The results showed that the optimal concentration of NaOH to remove lignin was 10% which generated 17.40% lignin content, 20.81% cellulose, and 3.79% hemicellulose. The highest bioethanol content was 100% obtained with a fermentation time of 72 hours. The data showed that adding of NaOH and fermentation time affected bioethanol production.