Enhancement of the enzymatic digestibility from sugarcane bagasse by moderate alkaline/sulfite-chemithermomechanical treatment

Sulfite process is able to remove lignin from a large variety of plants and it has been known to produce pulps with high yields and better mechanical properties. In addition, the lignocellulosics pretreatment with SO₃^-2 ions makes residual lignin sulfonated and hydrophilic, enabling cell wall’s porosity and enzymes access to cellulose chains. Sugar cane bagasse is recalcitrant to enzymatic digestion, which hinders the efficient conversion of its polysaccharides into fermentable sugars. Alkaline-sulfite pretreatment was used to overcome the sugar cane bagasse or cellulignin recalcitrance. Chemical and structural changes that occurred during the pretreatment were correlated with the efficiency of the enzymatic digestion of the polysaccharides. Most of the delignification occurred within 30 min of pretreatment, whereas sulfonate groups continued to be incorporated into the residual lignin. The selectivity (% lignin removed/yield drop) for the different pretreatments was lower at the beginning of cooking. On the other hand, there was a considerable increase in selectivity for the harshest sulfite pretreatment. In this presentation, we will compare the effect of lignin sulfonation and hemicelluloses removal at different pretreatments strategies on the enzymatic hydrolysis of sugarcane bagasse.