Hydrolysis Process of Red Sorghum Grains for Producing Bioethanol

Abstract

As part of the effort to continuously enhance the development and utilization of bioenergy/bioethanol and to ensure its sustainability, using sorghum as a raw material for bioethanol production requires a study to obtain efficient hydrolysis conditions and achieve optimal bioethanol conversion. This research method is divided into two main parts: samples with pretreatment and without pretreatment. The pretreatments used NaOH solution (0.05% and 0.1%); soaking temperatures at 35,40 and 45^oC; and soaking time at 30, 60, 90, and 120 minutes. The liquefaction and saccharification results with pretreatment showed a greater decrease in viscosity values after both liquefaction and saccharification, and the RS and DE results also demonstrated an increasing trend compared to samples without pretreatment. It is due to the presence of protein bodies in sorghum that inhibited hydrolysis without applying the pretreatment. The best result on the reduced sugar (RS) value achieved was 10.43%, and the DE value was 67.90%. Thus, the optimum operational condition was achieved with a sample with 0.05% NaOH soaking for 90 minutes at 45°C (A9). Subsequently, fermentation was carried out on sample A9 with pretreatment and sample without pretreatment (A0/B0). The alcohol obtained from fermentation with pretreatment was 9.5%, with a fermentation ratio (FR) of 86.97%. Meanwhile, the alcohol yield from fermentation for the sample without pretreatment was 8.9%, with an FR of 83.02%.