Valorization of Unripe Plantain (Musa paradisiaca) Peel for a Renewable Bioethanol Production

Abstract: The increasing demand for sustainable alternatives to fossil fuels has stimulated interest in lignocellulosic biomass as a renewable feedstock for bioethanol production. This study assessed the potential of unripe plantain (Musa paradisiaca) peels as a lignocellulosic substrate for bioethanol production, with emphasis on physicochemical composition, reducing sugar recovery, inhibitor reduction and ethanol yield. Fresh unripe plantain peels were washed, sundried, milled and subjected to combined pretreatment using a combination of 10% formic acid and 5% tetraoxosulphate vi acid at 121oC for 30min, followed by acid hydrolysis. The physicochemical composition of the raw and pretreated biomass were determine using standard methods. The raw unripe plantain peel contained 54.34% carbohydrate, 28.60 cellulose, 17.40% hemicelluloses and 13.80% lignin. Following acid pretreatment, cellulose increased to 48.63.%, while hemicelluloses and lignin decreased to 8.63% and 7.46% respectively, indicating effective disruption of the biomass structure. The acid hydrolysis of the pretreated biomass produced a hydrolysate with 21.59g/l reducing sugars, corresponding to 51.80% sugar recovery. Detoxification of the hydrolysate using overliming and activated at 1:3 and 3:1 ratios reduces the inhibitor index by 40,98% and 54.76% respectively, with 3:1 ratio showing greater detoxification efficiency. Fermentation of the hydrolysate using yeast produced an ethanol concentration of 3.82g and 14.86% yield for undetoxified sample, 6.43g and 38.91% yield at 1:3 ratio, and 8.42g and 50.18% at 3:1 detoxification ratio. The findings demonstrate that unripe plantain peels possesses considerable potential as a renewable lignocellulosic feedstock for bioethanol production. Valorization of unripe plantain peel waste contributes to waste management, renewable energy generation, and sustainable biofuel development.

Keywords: Lignocellulosic biomass, Renewable energy, unripe plantain peels, Fossil fuel, Bioethanol