The purpose of this work was to study the purification and isolation (downstream process) of the beta-glucan extracted from barley in an ultrasound assisted extraction (UAE) process. The co-extracted starch (average concentration 5.2 +/- 0.1 g/L) was hydrolyzed by means of alpha-amylase. The optimization of the hydrolysis length, temperature and enzyme dose led to removal efficiencies higher than 90% (9 min hydrolysis length and enzyme doses of 100 mu L/g at 55 degrees C), compared to the traditional hydrolysis processes (1 h at 95 degrees C). In a second step, a significant intensification of the process has been achieved by dosing the enzyme during the UAE step (7 min at 55 degrees C), resulting in a starch removal of 90%. Dextrins and other oligosaccharides were formed as a consequence of the enzymatic hydrolysis. In order to separate these low molecular weight molecules from the beta-glucan (239 kDa), an ultrafiltration process (polysulfone membrane, nominal MWCO 100 kDa) was tried in a tangential flow cell: diafiltration successfully eliminated more than 45% of the oligosaccharides present in the liquid, providing a significant increase in the concentration of beta-glucan and with the possibility of improving the percentage of elimination. The combination of these three technologies (UAE, enzymatic hydrolysis and diafiltration) allows getting high purity beta-glucan concentrates (greater than 70%). (C) 2014 Elsevier B.V. All rights reserved.