Intensification of delignification using steam explosion combined with enzymatic hydrolysis for enhanced fermentable sugar production

Abstract

Soybean hull is an agro-industrial residue widely generated due to the high productivity of soybean. This residue has high holocellulose content, which makes it feedstock for the production of fermentable sugars through the enzymatic hydrolysis process. This study evaluated the enhancement in fermentable sugar production from soybean hull through pretreatment by steam explosion before enzymatic hydrolysis. The steam explosion was evaluated by varying the reaction time of 2.5, 5, and 10 min at 180 °C and 5 MPa. Enzymatic hydrolysis was assessed from the activity of the enzyme filter paper unit (15 and 30) and load of the soybean hull in natura and soybean hull pretreated (1 % w/v and 2 % w/v). The results showed that steam explosion produced fermentable sugar (3.88 g/ 100 g), a difficultly quantified and reported result, in addition to recalcitrance reduction of the biomass, intensifying the total sugar yield in enzymatic hydrolysis. The highest sugar yield in enzymatic hydrolysis with soybean hull pretreated was 97.55 g/ 100 g, at 15 enzyme filter paper unit and 1 % load of the soybean hull. Steam explosion and enzymatic hydrolysis combined produced a maximum of 101.43 g/ 100 g, about 2.72 times than only enzymatic hydrolysis under the same conditions.