Fermentable sugar production from rapeseed straw by dilute phosphoric acid pretreatment

Rapeseed straw, as an agricultural residue, does not compete with food use and it can be used as a feedstock for bioethanol production. In this work, previously to enzymatic hydrolysis, phosphoric acid was used to pretreat this raw material and the influence of the main parameters was evaluated on the enzymatic hydrolysis yields and hemicellulosic sugars recovery in liquid fractions. Experimental design and response surface methodology were applied using pretreatment temperature (146.36-213.64 degrees C), time (4.77-55.23 min) and phosphoric acid concentration (0.32-3.68%, w/v) as factors. Considering maximization of the enzymatic hydrolysis yield as optimization criterion, results show that 87% of the glucose content in the raw material can be released by enzymatic hydrolysis at 202 degrees C, 5 min and 0.32% H3PO4, which is equivalent to 41.1 g sugars/100 g rapeseed straw. (C) 2013 Elsevier B.V. All rights reserved.