Influence of growth temperature on content, viscosity and relative molecular weight of water-soluble β-glucans in barley (Hordeum vulgare L.)

beta-Glucan content and viscosity of water-soluble beta-glucans have a considerable impact on the digestion of barley. Eight different 2-row barley (Hordeum vulgare L.) cultivars were grown in controlled environment chambers at five different temperatures until maturity. The samples were pearled, milled and analysed for their content of total, insoluble and soluble beta-glucan. The water-soluble fraction was extracted at 37 degrees C, subjected to amylase treatment and freeze-dried. Water-soluble crude beta-glucans were solubilised in distilled water, analysed for viscosity and their purity was checked by nuclear magnetic resonance. Molecular weights were profiled by size exclusion chromatography with RI detection. The content of total beta-glucan varied from 4.0% to 7.4%, and was significantly affected by the growth temperature. An interaction between cultivar and growth temperature was observed for the total beta-glucan content. The extractability was significantly affected by growth temperature, as there was recorded an increasing amount of water-soluble beta-glucan with increasing growth temperature. Both the viscosity and the molecular weight of the water-soluble beta-glucans increased with the growth temperature. (C) 2008 Elsevier Ltd. All rights reserved.