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

Abstract

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 -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.

Furfural production from birch hemicelluloses by two-step processing: a potential technology for biorefineries

“…Xylooligosaccharides (including the ones of low and high DPs) and xylose are the major potential substrates for F production. The kinetic model predicted a maximum xylooligosaccharide concentration of 23.5 g l -1, which is in the range reported in related studies (Garrote et al 2008;Yáñez et al 2009). In this work, these conditions were selected for further operation, which lead to maximum yield of the total F concentration, C5 sugars, and their oligomers and polymers.…”

“…This goal can be achieved by a hot water extraction (also called autohydrolysis, hydrothermal treatment, or water prehydrolysis) (Yáñez et al 2009;Helmerius et al 2010;Gullón et al 2011;Vila et al 2012), which is considered to be an environmentally friendly technology and enables a selective separation of soluble hemicellulose-derived saccharides, while the solid phase residue is enriched in cellulose and lignin. The latter can be further fractionated via autohydrolysis, for example, to produce pulp (Helmerius et al 2010), dissolve pulp (Borrega et al 2013;Testova et al 2014), microcrystalline cellulose (Vila et al 2014), or sugar solutions suitable as fermentation media for the biotechnological manufacture of chemicals or fuels (Garrote et al 2008).…”

Fractionation of Hemicelluloses and Lignin from Rice Straw by Combining Autohydrolysis and Optimised Mild Organosolv Delignification

“…The products that can be obtained include sulphur-free lignin fragments, which are useful for the production of lignin-based high value products due to their high purity, low molecular weight, and easily recoverable organic reagents (Garrote et al 2008;Toledano et al 2012). If applied directly to the lignocellulosic material, the organosolv treatment will yield a liquid stream containing both lignin and hemicellulosederived products that will require major purification for lignin recovery (Harmsen et al 2010).…”

Biorefinery processes for the integral valorization of agroindustrial and forestal wastes Procesos de biorrefinería para la valorización integral de residuos agroindustriales y forestales

“…As general trend, more severe operating conditions led to a decrease in oligomer concentration in liquid phase (due to decomposition reactions) and an increase in glucose concentration in enzymatic hydrolysis. In the severest autohydrolysis conditions, a slight decrease in glucose concentration can be observed in agricultural residues, as with corn cobs, with a decrease of 29.3% of maximum glucose concentration with increasing autohydrolysis maximum temperature from 210 to 2168C (Garrote, Ya´n˜ez, Alonso, & Parajo´, 2008), or with barley husks, with a decrease of 10.1% with increasing autohydrolysis maximum temperature from 210 to 2168C (Ares-Peó n, Vila, Garrote, & Parajo´, 2011). With a typical hardwood, Eucalytpus globulus, no decrease in maximum glucose concentration with increasing autohydrolysis temperature was observed (Romanı´, Garrote, Alonso, & Parajo´, 2010b).…”