bio-conversion of apple pomace into ethanol and acetic acid: enzymatic hydrolysis and fermentation

enzymatic hydrolysis of cellulose present in apple pomace was investigated using process variables such as enzyme activity of commercial cellulase, pectinase and β-glucosidase, temperature, ph, time, pre-treatments and end product separation. the interaction of enzyme activity, temperature, ph and time had a significant effect (p < 0.05) on release of glucose. optimal conditions of enzymatic saccharification were: enzyme activity of cellulase, 43 units; pectinase, 183 units; β-glucosidase, 41 units/g dry matter (dm); temperature, 40 °c; ph 4.0 and time, 24 h. the sugars were fermented using saccharomyces cerevisae yielding 19.0 g ethanol/100 g dm. further bio-conversion using acetobacter aceti resulted in the production of acetic acid at a concentration of 61.4 g/100 g dm. the present study demonstrates an improved process of enzymatic hydrolysis of apple pomace to yield sugars and concomitant bioconversion to produce ethanol and acetic acid.