Purification of oligosaccharides obtained from Pinus pinaster hemicelluloses by diafiltration

The aim of this work was to assess the performance of diafiltration as a method for purification of oligosaccharides obtained by autohydrolysis of Pinus pinaster wood. Pinus pinaster wood hemicelluloses are mainly made up of galactoglucomannans, which were partially hydrolyzed in aqueous treatments (autohydrolysis) performed under suitable operational conditions (isothermal processing at 175 degrees C for 24.5 min). The oligosaccharides present in autohydrolysis liquors obtained under optimal conditions were purified by diafiltration in a dead-end filtration device using a regenerated cellulose membrane (1 kDa MWCO). Continuous diafiltration resulted in increased weight percent of substituted oligosaccharides respect to the total nonvolatile solutes (from 79.2% up to 94.7%), as well as in the selective removal of monosaccharides (the substituted oligosaccharides to monosaccharides ratio increased from 4.3 up to 17.8).