Liquid hot water pretreatment of sugarcane bagasse and its comparison with chemical pretreatment methods for the sugar recovery and structural changes

► Liquid hot water process has no chemical addition but a good sugar recovery. ► Ultrastructural change of cell wall was observed for different pretreated samples. ► Lignin can migrate within and out of the cell wall in the hydrothermal pretreatment. ► A combined pretreatment with liquid hot water and aqueous ammonia was proposed.