Integrated treatments of steam explosion and enzymatic hydrolysis to produce energetic and industrial products from lignocellulosic biomasses

In this work the authors have evaluated the steam explosion effect on vine-shoots in different process conditions as well as the integration of steam explosion pretreatments with the enzymatic hydrolysis in order to improve the simple sugar production from lignocellulosic biomasses. Steam explosion treatments (SE), increasing the severity index (SI) between 2.94 and 4.28, show; i) an increment of the pentose and total sugar amounts int he soluble fraction; ii) a decrease of the ethanol insoluble residue (EIR) associated with an increase of cellulose amount as a consequence of the degradation of pectin, hemicellulose and, probably, lignin. Furthermore, the SE pretreatment improves enzymatic hydrolysis. In fact, treatments with cellulolytic enzymes alone are poorly efficient, decreasing the EIR from 85.47 to 79.68% of dry weight (d.w.) and consequently the cellulose amount from 19.55 to 17.17% d.w. The integration of these two treatments reduces the amount of EIR from 85.47 to 37.26 g% of d.w. and the one of cellulose from 19.55 to 7.71 g% of d.w. These results show the synergistic effect that the steam explosion has on enzymatic hydrolysis of cellulose.