Extraction of hemicellulose from sugarcane bagasse to obtain pentoses and xylooligossacharides

Abstract

The aim of this project is to obtain xylooligossacarides (Xo), by chemical and enzymatic hydrolysis of sugarcane bagasse. First stage, the hemicellulosic fraction of the sugarcane bagasse will be extracted with 1M NaOH and then precipitated with 95% v/v ethanol in order to isolate it from the soluble lignin. The non hydrolysed material (cellulignin) will be dried and kept for further analyses. The hemicellulose will be also hydrolysed by enzymes from Aspergillus niger and Thermoascus aurantiacus, which will be produced in our laboratory, using wheat bran as carbon source in semi-solid fermentation. In this stage, xilanases concentration and upstate percentage that maximize xylobiose (X2) and xylotriose (X3) production will be evaluated using the statistical analysis. Evaluation of the reaction at different times will allow a study on the behavior of the type Xo and xylose formed and on the Xo to xylose conversion. In a second stage, the bagasse will be autohydrolysed in a 50 L stainless steel reactor with agitation system, where the factors will be evaluated: percentage of solids, time and temperature in the Xo formation. The obtained Xo will be separated in gel filtration columns, using a series of three columns, loaded with gel Superdex 75, Superdex 75 (HR 10/30) and Superdex 200 (HR 10/30), respectively. The cellulignins obtained after autohydrolysis of the bagasse, as well as those obtained from the alkaline extraction will be characterized and submitted to hydrolysis by a commercial cellulase. The susceptibility of the three substrates to the cellulases action will be evaluated, since each one will present a different composition and cellulose/lignin ratio. (AU)