Efficient approach for bioethanol production from red seaweed Gelidium amansii

•Autoclaving treatment of GA can improve the glucose and ethanol conversion yield.•Autoclave-treated GA sample for 60 min is suitable for bioethanol production.•SSF recorded a 10.2% higher ethanol conversion yield than SHF.

Gelidium amansii (GA), a red seaweed species, is a popular source of food and chemicals due to its high galactose and glucose content. In this study, we investigated the potential of bioethanol production from autoclave-treated GA (ATGA). The proposed method involved autoclaving GA for 60 min for hydrolysis to glucose. Separate hydrolysis and fermentation processing (SHF) achieved a maximum ethanol concentration of 3.33 mg/mL, with a conversion yield of 74.7% after 6 h (2% substrate loading, w/v). In contrast, simultaneous saccharification and fermentation (SSF) produced an ethanol concentration of 3.78 mg/mL, with an ethanol conversion yield of 84.9% after 12 h. We also recorded an ethanol concentration of 25.7 mg/mL from SSF processing of 15% (w/v) dry matter from ATGA after 24 h. These results indicate that autoclaving can improve the glucose and ethanol conversion yield of GA, and that SSF is superior to SHF for ethanol production.