Enhanced bioethanol production from pretreated corn stover via multi-positive effect of casein micelles

► Casein, a phosphoprotein, used as an enzyme-aid or lignin-blocker of corn stover (CS). ► Effect of casein tested on dilute acid, lime, alkali, extrusion and AFEX pretreated CS. ► Casein increased the glucose and ethanol yield up to 31.9% and 33.7%, respectively. ► Application of casein reduced the fermentation time by up to 48 h. ► Increased enzyme recycling with casein increased the sugar yield by 25.5% in 2nd cycle.