Hydrothermal treatment of sugars to obtain high-value products

Abstract

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, acetone-soluble 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.