Mixed-linkage beta-glucan from barley, with a cellotriosyl to cellotetraosyl ratio of 2.9, was hydrolysed with two endo-1,4-beta-glucanases (cellulases) and one non-cellulolytic P-glucanase isolated from Trichoderma reesei. The hydrolysates were precipitated in 90% ethanol and the fragments obtained were further treated with lichenase, followed by analysis of the oligosaccharides released. One of the endo-1,4-beta glucanases, Cel 5A (EG II), selectively degraded cellotetraosyl units in the polymer and left the cellotriosyl units unhydrolysed. Blocks of cellotriosyl units were isolated on a larger scale using this enzyme. The isolated blocks were fractionated into four fractions using gel permeation chromatography on Biogel P-6 and the structures of the blocks were analysed by H-1 NMR spectroscopy. The fractions essentially contained cellotriosyl units of different sizes with a 3-linked glucose residue at the non-reducing end and a reducing end linked to two 4-linked glucose residues. The results thus indicated that the enzyme could hydrolyse a 4-linked glucose residue next to the 3-linked residue at the non-reducing terminal but left two 4-linked glucose residues at the reducing end. The isolated blocks of cellotriosyl units had a molecular weight distribution that fits a theoretical model based on random blocks of triosyl units in the mixed-linkage beta-glucan. (c) 2005 Elsevier Ltd. All rights reserved.

beta-(1-->3),(1-->4)-D-Glucan (beta-glucan) was extracted from 93 Swedish and 41 American oat samples using hot water containing CaCl(2) and thermostable alpha-amylase. The samples showed a large variation in both the content of extractable beta-glucan (0.76-3.68%) and the average molecular weight ((1.25-1.78) x 10(6) g mol(-1)). An analysis of the variance of beta-glucan content and the molecular weight of Swedish oat samples grown in 2000 and 2001 was done with cultivar and harvest year as factors. It showed that the extractable beta-glucan content was a heritable trait whereas molecular weight depended more on environmental factors. The American oat samples had a higher average content of extractable beta-glucan (2.24%) and a somewhat higher average molecular weight (1.58 x 10(6) g mol(-1)) than the Swedish oat samples (1.43% and 1.49 x 10(6) g mol(-1)).

Starch was isolated from four new waxy barleys and compared with normal and high-amylose barley starch. The waxy barley samples were selected lines from crosses of Swedish hulled and naked barley cultivars with the cultivar Azhul as donor of the waxy gene. The starches from the waxy barley samples were found to contain 0.7-2.6% amylose when determined iodimetrically by amperometric titration and 0.0-0.9% when determined by size exclusion chromatography after debranching. However, Sepharose CL-213 elution profiles of the starches detected by iodine staining showed that all four waxy samples were free from detectable amounts of amylose. The amylopectin starches were found to contain a small polysaccharide fraction with molecular size smaller than amylopectin, with an iodine staining lambda(max) range of 550-600 nm. The water extractable and acid extractable beta-glucan contents in the waxy barley cultivars were generally found to be higher than those in normal barley.