Study of the effect of different pretreatments on the performance of the extraction of β-glucan from barley

The aim of this work is to study the effect of different pretreatments on the extraction of beta-glucan from barley in order to optimize the overall process. Two different treatments were studied separately: ultrasounds, to enhance the final extraction yield, and ethanol to increase the molecular weight of those beta-glucans extracted. Barley flour was boiled with ethanol (80%, v/v), prior to extraction stage, for two hours. According to the results obtained by size exclusion chromatography, this treatment increased the molecular weight of the polymers from 32000 Dalton to 717000 Dalton, leading to much higher viscosity solutions. When the use of ultrasounds as pretreatment was tried, extraction yield was increased dramatically in all the tests carried out (9 different ultrasound conditions were tested). In all cases beta-glucan extraction yield was over 80% (compared to 47,2+/-2,4% obtained when barley was not sonicated). The best result was obtained when barley was sonicated for 30 seconds, at 78% of the total power of the ultrasound equipment (yield 87,7+/-2,5%).