Hydrothermal treatment of sugars to obtain high-value products

In the present work, the degradation of different sugars, such as lactose, cellobiose, sucrose, galactose, glucose, fructose and xylose, was performed in batch reactor with subcritical water at temperature of 250 °C and reaction time of 1, 5 and 15 min. The yields of water-soluble phase, acetonesoluble phase, solid residue and gases were determined. The influence of reaction time and difference in sugar structure on the yield of phases and conversion of sugars was studied. Sugars with keto- and furanose structures were less stable than aldo- and pyranose-sugars. The most stable sugars were aldo-hexoses (galactose and glucose). The water-soluble fraction, which is composed of sugars and their derivatives, was analyzed by HPLC using RI and UV detectors. The detected degradation products by HPLC were: 5-hydroxymethylfurfural (5-HMF), furfural, erythrose, sorbitol, 1,6-anhydroglucose, glycolaldehyde, glycerlaldehyde, 1,3-dihydroxyacetone, pyruvaldehyde, formic, levulinic, lactic, oxalic and succinic acids.