Elaeis guineensis (E. guineensis) oil palm tree (OPT) presented a novel biomass source, with its OPT sap demonstrating the potential for bioethanol production due to its rich sugar content. The increasing waste of the OPT necessitated exploring ways to maximize its utilization and functionality, making bioethanol production a pertinent avenue for sustainable resource utilization. This study aimed to compare the bioethanol yield concentration production in optimized conditions and non–optimized conditions based on response surface methodology (RSM) data from Box–Behnken design (BBD). This study also investigated the viability of felled E. guineensis OPT sap for bioethanol production on the effect of sugar composition and fermentation conditions. Analysis revealed significant variations in fructose, glucose, and sucrose levels across different trunk segments, with sucrose notably higher in some areas. Using Saccharomyces cerevisiae (S. cerevisiae) Kyokai no. 7 in a 2L bioreactor, the study employed repeated batch fermentation to explore the efficiency of bioethanol yield production across 13 cycles under optimized and non–optimized conditions. The optimized fermentation conditions included a felled E. guineensis OPT sap medium with an initial pH of 6.50, supplemented with 6.80 g/L of peptone and 13.28 g/L of corn steep liquor (CSL) at 30°C. The non–optimized conditions were similar but conducted at room temperature. The maximum bioethanol yield concentration of 35.65 g/L, averaging 23–35 g/L per cycle, highlighted the effectiveness and stability of repeated fermentation under optimized conditions, with the bioethanol yield ranging from 3–4 volume/volume percentage (v/v %). The optimized condition significantly improved bioethanol concentration (38.42 %) and volume content (28.67 %), enhancing production efficiency. Bioethanol yield production was markedly improved under optimized conditions, as confirmed by statistical analysis, while non–optimized settings yielded unstable reported data. This research highlighted the importance of controlled environmental conditions and optimized fermentation processes. The study underscored the potential of felled E. guineensis OPT sap as a biomass source for bioethanol, suggesting promising avenues for the scale–up of bioethanol production in the future.
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