Pengoptimuman Pengeluaran Bioetanol Menggunakan Strain Yis Tempatan yang Diasingkan dari Malaysia Melalui Sel Yis Terkurung dalam Bebola Alginat

Research in production of bioethanol has been accelerating since the world faced depleting fossil fuels. To obtain high ethanol yield and fermentation rate, response surface methodology (RSM) was applied to study the effect of medium and alginate-ST1 yeast cell beads toward production of bioethanol using local yeast strain called ST1. Bioethanol was produced by immobilized ST1 yeast grown in local brown sugar (LBS) using shake flask mode at 30˚C for 6 hour and the effect of LBS concentrations, ratio of alginate (ST1) beads to the medium volumes and the beads size were investigated. Firstly, 2<sup>3</sup> full factorial design (first order model) was carried out to identify the significant effect prior to second-order model; central composite design (CCD) can be proposed. The first order model analysis showed that the selected parameters are significant in glucose utilization and bioethanol production. The total bioethanol production was 5.30 g/L under optimum conditions, an increase of 14.16% compared to the production before optimization, which was 4.73 g/L. The CCD results showed that the optimum conditions for bioethanol production were at a ratio of 125 g/L LBS for LBS concentration, 0.47 for the ratio of alginate beads to medium volume, and 0.33 cm for alginate bead size. Overall, this study demonstrated the successful immobilization of ST1 yeasts in alginate, which improved the effectiveness and productivity of bioethanol production. This approach offers a more sustainable solution, as the yeast cells can be reused, thereby shortening the harvesting process and contributing to a more efficient bioethanol production system.