Optimisation of Bioethanol Production from Musa Paradisiaca Peels Using Box-Behnken Response Surface Methodology

Abstract

This study investigated the use of ripe plantain peel waste (Musa paradisiaca) as a lignocellulosic substrate for bioethanol production using Saccharomyces cerevisiae. The study characterised plantain peel and optimised acid hydrolysis and subsequent fermentation conditions using Box-Behnken response surface methodology. Ripe plantain peels collected in Uyo Local Government Area, Akwa Ibom State, Nigeria, were washed, dried, milled, and pretreated before dilute sulphuric acid hydrolysis. A three-factor, three-level Box-Behnken design comprising 20 experimental runs was used for both hydrolysis and fermentation. Hydrolysis was evaluated using acid concentration, reactor temperature, and reaction time, while fermentation was optimised using pH, fermentation time, and acid concentration. Sugar content of the hydrolysates was estimated using the Brix method. The optimum hydrolysis conditions were 80 °C, 0.5% (v/v) acid concentration, and 10 min, with R² = 0.8021 and adjusted R² = 0.6240. The fermentation model was highly significant, with R² = 0.9716 and adjusted R² = 0.9461. The maximum reported bioethanol yield was 32.7042% (v/v) at 1.0% acid concentration, pH 5.0, and a fermentation period of 2 days. However, the hydrolysis model exhibited significant lack of fit (p = 0.0002), indicating that its predictive performance should be interpreted cautiously. Overall, the findings demonstrate the potential of plantain peel waste as a renewable lignocellulosic substrate for bioethanol production and provide a statistical basis for further optimisation and validation of the process.