The Saccharification of Agricultural Residues: A Continuous Process

Excerpts from the report: Because of the chemical composition and physical properties of agricultural residues, they may find a unique place in the field of industrial saccharification. A continuous process for the saccharification of agricultural residues which makes use of these properties has been developed through a large- scale laboratory stage. This process is a two-stage operation in which the pentosans are first hydrolyzed by dilute acid. The cellulose is then saccharified by a new concentrated acid method which uses less than one fourth the amount of acid required by other known concentrated acid processes. The lignin remains as an insoluble residue. The methods employed enable almost quantitative separation of pentosans and cellulose. The pentosan hydrolysis yields a 15 to 20% xylose solution. The cellulose hydrolysis yields a 10 to 12% dextrose solution. The dextrose, which is obtained in yields of 85 to 90% of theoretical, is readily fermented by A. aerogenes and yeast. Five agricultural residues—corncobs, sugar-cane bagasse, flax shives, oat hulls, and cottonseed hulls—were used in this development. Since optimum reaction conditions as well as yield of products from all five residues were similar, only the data on corncobs will be reported.