Alkali Impregnation and Steam Explosion of Cogon Grass for Improved Enzymatic Saccharification

Abstract

Process parameters for the alkali-impregnation of cogon and its combination with steam explosion were evaluated and optimized using Response Surface Modeling (RSM). Dried cogon (10% w/v) was impregnated in diluted base (1, 2, 3% (w/w) NaOH) at different ranges of temperature (50, 85,120 °C) and time (15, 32.5, 50 min), and then subjected to enzymatic saccharification using 60 FPU/g Accelerase 1500TM. The concentration of reducing sugar released was measured using Nelson-Somogyi Colorimetric Method. The RSM showed that the optimum condition, predicting 10% Reducing Sugar Yield (RSY), was treatment of 10 % (w/v) cogon with 1.5% NaOH (w/v) at 73 °C for 15 min. Upon validation, done in triplicates, 13+1.0% RSY was obtained. The optimally-impregnated cogon was subjected to a steam explosion treatment to improve its saccharifiability. The factors varied were temperature (170 to 225 °C) and exposure time (250 to 800 s). Upon saccharification of the steam-exploded samples, the RSM indicated that the best steam explosion condition, predicting 14% RSY, was 225 °C and 800 s. Upon validation, 15+0.5% RSY was obtained. Steam explosion improved the saccharifiability of NaOH-impregnated cogon by 15%.