Manufacture and Refining of Oligosaccharides from Industrial Solid Wastes

The waste solid obtained in the malting industry, made up of barley husks, fragments of barley grains, and spent barley grains, was treated with water (autohydrolysis reaction) under optimized conditions to cause the hydrolytic degradation of susceptible saccharides (hemicellulosic fraction of barley husks and starch of grain fragments and spent grains). The major portion of the substrate solubilized in autohydrolysis corresponded to nonvolatile components (NVC), which were made up of hemicellulose-derived products (substituted oligosaccharides and monosaccharides), starch-derived products (glucose and glucooligosaccharides), and other nonvolatile components (ONVC). To increase the mass fraction of saccharidederived compounds in the NVC, concentrated autohydrolysis liquors were extracted with ethyl acetate, and the resulting aqueous phase was subjected to alternative treatments (solvent precipitation, freeze-drying-solvent extraction, and ion exchange). The amount and composition of the phases was determined, and material balances are presented for several operational schemes. Ion exchange resulted in an isolate containing (per 100 kg of NVC) 11.27 kg of monosaccharides, 70.80 kg of oligosaccharides and oligosaccharide substituents, and 17.93 kg of ONVC. The ONVC fraction was mainly made up of acid-soluble lignin and melanoidins.