Coproduction of Oligosaccharides and Glucose from Corncobs by Hydrothermal Processing and Enzymatic Hydrolysis

Corncobs were subjected to nonisothermal reaction in aqueous conditions to reach temperatures in the range 202−216 °C. The liquors were assayed for composition to assess the conversion of xylan into oligosaccharides and reaction byproducts, whereas the spent solids from treatments were subjected to enzymatic hydrolysis. Enzymatic assays were carried out according to an incomplete, factorial, centered design of experiments, in which the following independent variables were considered: liquor to solid ratio (in the range 6−16 g/g), enzyme to substrate ratio (in the range 6−28 filter paper units/g), and β-glucosidase activity/cellulase activity ratio (in the range 1−9 IU/FPU). The concentration/time data were fitted to an equation selected from the literature, and the model parameters were expressed as a function of the operational variables considered in the experimental design. Under selected conditions, high oligosaccharide yields and near quantitative cellulose conversion into glucose were obtained.