Postharvest losses of tropical fruits represent an underexplored feedstock for renewable fuels. This study evaluates the feasibility of converting discarded Carica papaya L. var. Maradol pulp into fuel-grade ethanol via batch fermentation and fractional distillation. Peeled fruit (4.0 kg) was pasteurized, adjusted to 22 °Brix with brown sugar, and inoculated at 1 × 106 cells mL?1 with Saccharomyces cerevisiae Ethanol Red™. Triplicate fermentations were performed at 30 ± 0.2 °C for 192 h, and kinetic parameters were determined by HPLC, GC-FID, and a modified Gompertz model. Soluble sugars declined from 205 to 17 g L?1 within 96 h, yielding 92.3 ± 1.8 g L?1 ethanol. Volumetric productivity and ethanol yield reached 1.04 ± 0.05 g L?1 h?1 and 0.46 ± 0.01 g g?1, respectively—90 % of the theoretical maximum. Distillation with a 64–78 °C heads cut produced a 95.4 ± 0.6 % v v?1 ethanol distillate, with methanol, water, Sulphur, and acidity within ASTM D4806 limits. The process delivered 68.4 ± 1.3 g ethanol kg?1 fresh fruit (? 1.45 MJ kg?1) and vinasse with a C:N ratio of 8.1, suitable for fertigation or anaerobic digestion. Kluyveromyces marxianus showed thermotolerance and moderate yields, while Pichia kudriavzevii achieved higher concentrations. Native isolates like Lactobacillus plantarum, Acetobacter tropicalis, and wild Saccharomyces spp. support co-culture strategies. These results position Maradol papaya waste as a viable, low-cost substrate for decentralized bioethanol production and circular bioeconomy systems.
circular bioeconomy; ethanol yield; fuel quality; process kinetics; tropical fruit residues
Duque-Dussán, E., Figueroa-Varela, PA., Munoz-Salazar, S. (2026): High-Efficiency Bioethanol Production from Maradol Papaya Waste: Batch Fermentation and Fractional Distillation. Scientia Agriculturae Bohemica, 57, 1, DOI: 10.7160/sab.2026.570102