Pretreatment and enzymatic saccharification of corn fiber.

Corn fiber consists of about 20% starch, 14% cellulose, and 35% hemicellulose, and has the potential to serve as a low-cost feedstock for production of fuel ethanol. Several pretreatments (hot water, alkali, and dilute acid) and enzymatic saccharification procedures were evaluated for the conversion of corn fiber starch, cellulose, and hemicellulose to monomeric sugars. Hot water pretreatment (121 degrees C, 1 h) facilitated the enzymatic saccharification of starch and cellulose but not hemicellulose. Hydrolysis of corn fiber pretreated with alkali under similar conditions by enzymatic means gave similar results. Hemicellulose and starch components were converted to monomeric sugars by dilute H2SO4 pretreatment (0.5-1.0%, v/v) at 121 degrees C. Based on these findings, a method for pretreatment and enzymatic saccharification of corn fiber is presented. It involves the pretreatment of corn fiber (15% solid, w/v) with dilute acid (0.5% H2SO4, v/v) at 121 degrees C for 1 h, neutralization to pH 5.0, then saccharification of the pretreated corn fiber material with commercial cellulase and beta-glucosidase preparations. The yield of monomeric sugars from corn fiber was typically 85-100% of the theoretical yield.