Characterization of yeast extract co-product bioethanol from empty palm oil bunch Muhamad Sahlan, Charion Gibreth Hannes, Yanni Sudiyani, Heri Hermansyah and Anondho Wijanarko E3S Web Conf., 67 (2018) 03039 Published online: 26 November 2018 DOI: 10.1051/e3sconf/20186703039