Optimization of enzymatic saccharification of mixed rice biomass to produce fermentable sugar

Abstract

Conversion strategy of lignocellulosic biomass into fermentable sugar by alkaline pretreatment is one of the most feasible routes. The objective of this study was to investigate the optimization of enzymatic saccharification process condition that exploits the use of alkaline pretreatment for increment of sugars production. Commercial cellulase known as Celluclast® 1.5L is a new technology has been introduced in order to meet optimization process condition and analyzed by employing Central Composite Design (CCD) in Response Surface Methodology (RSM) using Design Expert Version 7.5.1 (StatEase, USA). In this study, the process condition parameters for enhancing sugars production in alkaline pretreatment were: autoclaved at temperature 121°C under sodium hydroxide concentration 1.0% (w/v) within 20 min. Optimum process condition of enzymatic saccharification will have the optimum at pH 5.53, temperature at 50 °C, enzyme loading at 0.8 mL and substrate loading at 0.24 g producing 4.149 g/L reducing sugars concentration at efficiency of saccharification yield by 85.50%. Temperature and pH showed more significant effect for enhancement of sugars compared enzyme loading and substrate loading. It was evident that composition of hemicellulose, cellulose and lignin of the mixed rice biomass were affected by the alkaline pretreatment condition based on Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM) analysis. FTIR showed alteration in functional group while the SEM micrographs showed a marked change on pretreated sample when compared with untreated sample.