COMPARISON OF ACID AND ALKALI CATALYTIC EFFICIENCY DURING ENZYMATIC SACCHARIFICATION OF CORNCOB AND LACTIC ACID PRODUCTION

Corncob is an agriculture waste found to consist of 38.9% cellulose and 43.4% hemicellulose on dry solid (w/w %) basis and thus considered a potential source for fermentable sugars. These sugars can potentially be extracted through combined chemical pretreatment and enzymatic saccharification. The present study is aimed to optimized the pretreatment process by using variety of alkali and acids includingH2SO4, HCl, H3PO4, C2H2(COOH)2, CH3COOH, NaOH, NH3OH and H2O as a catalyst at different temperatures and reaction time ranged from 100–130°C and 0.5-5h, respectively. The pretreated biomass was then hydrolyzed with cellulose enzyme (Accellrase 1500) for production of fermentable sugars. The H3PO4 and C2H2(COOH)2 treated material showed 88+1% hydrolysis yield while NaOH and NH3OHyielded 95.0%. The order of catalytic effectiveness on enzymatic hydrolysis remained as NaOH NH3OH H3PO4 C2H2(COOH)2 HCl H2SO4 CH3COOH H2O. Acids also bequeath 30-42gL^-1 of reducing sugars during pretreatment step, while alkali degrades them. Pure glucose obtained from H2SO4 and HCl treated materials while mixture of xylose and glucose was obtained from alkali treated material. The resulting sugars obtained from enzymatic hydrolyzate were successfully fermented into lactic acid by using L. acidophilus, with above 90.0% conversion efficiency and 0.78 gL^-1h^-1 lactic acid productivity obtained from maleic acid treated enzymatic hydrolyzate.