This disclosure provides lignin-based enzymatic hydrolysis enhancer that includes ethanol-soluble, partially sulfonated lignin. Some embodiments provide a lignin-based enzymatic hydrolysis enhancer comprising AVAP® lignin. Certain embodiments provide a lignin-based enzymatic hydrolysis enhancer comprising AVAP® lignin and lignosulfonates. In some variations, a process for producing a lignin-based enzymatic hydrolysis enhancer comprises fractionating biomass with an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin; recovering the lignin; and generating a lignin-based enzymatic hydrolysis enhancer comprising the lignin. Surprisingly, the lignin-based enzymatic hydrolysis enhancer is experimentally able to enhance glucose yields by 10% or more.