Improved Enzymatic Hydrolysis of Corn Stover by Green Liquor Pretreatment and a Specialized Enzyme Cocktail

Abstract

An effective strategy for sugar production from corn stover was established through a combination of green liquor pretreatment (8% total titratable alkali charge, 40% sulfidity, 140 °C, and 1 h) and enzymatic hydrolysis with a specialized enzyme cocktail. Green liquor pretreatment was demonstrated as an effective first step for sugar production due to the selective removal of lignin (39.70%), high carbohydrate recovery yield (81.53%), and obvious enhancement of enzymatic hydrolysis after pretreatment. When a specialized enzyme cocktail (cellulase, β-glucosidase, and xylanase at a ratio of 1:1.88:6.61, supplemented with 0.05 g of PEG 6000 per g of glucan) was applied, near-theoretical hydrolysis yield was achieved (glucan hydrolysis yield of 93.53% and xylan hydrolysis yield of 86.00%). A total fermentable sugar production of 50.14 g was obtained per 100 g of dry corn stover, including 36.08 g of glucose and 14.06 g of xylose.