Comparative studies on the saccharification of banana peels by acid, enzyme and steam were carried out to examine the potential of banana waste for ethanol fermentation by Saccharomyces cerevisiae var. ellipsoideus. Hydrolysis of the substrate using 2·5% sulphuric acid at 15 psi for 15 min enhanced the reducing sugar content more than ten-fold. The maximum saccharification was 26·7% and 28·3% (wt basis) and 56·4% and 59·9% (CH2O basis) with 2·5% acid at 10 and 15 psi for 15 min. Further increases in sulphuric acid concentration and treatment duration had adverse effects on the hydrolysis. Steaming without pressure enhanced the saccharification six-fold, but steaming under pressure (at 10 psi) for 30 min gave better saccharification.
Maximum saccharification was achieved by hydrolysing banana-waste cellulose with a cellulase enzyme from Trichoderma reesei QM 9414. A yield of 1·38 and 0·78% (v/v) and 44·5 and 61·1% ethanol (mg g−1 reducing sugars) was achieved from cellulose and acid hydrolysed (2·5% at 15 psi for 15 min) banana peels, respectively.