Optimization of Bioethanol Yield from Liquid Pineapple Waste using Immobilized Saccharomyces cerevisiae var. ellipsoideus in PVA-Alginate-Sulfate Matrix

¹ School of Agricultural Science and Biotechnology, Faculty of Bioresources and Food Industry, Universiti Sultan Zainal Abidin, Besut Campus, 22200 Besut, Terengganu, Malaysia
² Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, Skudai, 81310 Johor Bahru, Johor, Malaysia

^* Corresponding author: azimah@utm.my

Abstract

The increasing significance of bioethanol as a viable alternative to fossil fuels is driven by the depletion of conventional energy sources and the urgent need to reduce greenhouse gas emissions. Utilizing industrial or food wastes for bioethanol production is highly promising due to their rich sugar content. This study explores the feasibility of producing bioethanol from liquid pineapple waste using immobilized Saccharomyces cerevisiae var. ellipsoideus ATCC560 within PVA-alginate-sulfate beads. The novelty of this work lies in the post-immobilization treatment of beads with boric acid, sodium alginate, and sodium sulfate, which enhanced bead stability, improved yeast activity, and increased ethanol yield. A statistical approach with a 2-level, 3-factorial design was employed, considering four variables: initial inoculum (3-6 g), temperature (30-50 °C), pH (4.5-5.5), and agitation speed (100-200 rpm). Additionally, Field Emission Scanning Electron Microscope (FESEM) analysis was performed to examine bead morphology. The optimal conditions for bioethanol production were identified, yielding a maximum concentration of 10.0438 g/L at pH 5.5, 30 °C, and 200 rpm using 3 g of beads. FESEM analysis verified the efficiency of this technique by confirming the successful immobilization of S . cerevisiae var. ellipsoideus within the matrix. This study highlights the potential of immobilized S. cerevisiae var. ellipsoideus to produce bioethanol from liquid pineapple waste, providing an environmentally friendly and sustainable approach to renewable energy production.