Astrilia Damayanti, Zuhriyan Ash Shiddieqy Bahlawan, Irene Nindita Pradnya, Andri Cahyo Kumoro, Nauroh Nadzifah, Hisam Mansur, Ikliliya Zahwa Maulidiya, Abdurrahman Kholish Faizi
High-gravity (HG) fermentation is a pivotal strategy for enhancing bioethanol concentration and reducing distillation costs. However, maintaining cell viability and fermentation efficiency over multiple cycles remains a significant challenge during scale-up. This study investigates the performance and operational stability of Saccharomyces cerevisiae immobilized in calcium alginate beads for HG glucose fermentation. The system was evaluated across 13 repeated batch cycles in both a laboratory-scale and a 2-L bench-scale Stirred-Tank Bioreactor (STR). Results demonstrated that the immobilized system achieved peak performance at an initial glucose concentration of 172 g/L, maintaining an average ethanol yield of (86.51 ± 1.41)% and a mean volumetric productivity of (0.40 ± 0.01) g/L·h across 13 repeated batch cycles. While scaling up to the 2-L STR, the beads remained structurally intact, without fragmentation, under hydrodynamic shear, maintaining consistent metabolic activity throughout the process. The findings demonstrate the high operational stability of the immobilized cell system, with potential for industrial applications, and provide a technical framework for the scaling-up of HG bioethanol production while maintaining consistent yield and structural integrity across 13 repeated cycles. © 2026 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/
Department of Chemical Engineering, Faculty of Engineering, Universitas Negeri Semarang, Kampus Sekaran, Gunungpati, Semarang, 50229, Indonesia; Department of Chemical Engineering, Faculty of Engineering, Universitas Diponegoro, Jl. Prof. H. Soedarto, SH Semarang, 50275, Indonesia
