Publication no. C-1997-0820-03R |  VIEW ARTICLE

Molecular Characterization of Barley beta-Glucans by Size-Exclusion Chromatography with Multiple-Angle Laser Light Scattering and Other Detectors.

B. E. Knuckles (1,2), W. H. Yokoyama (1), and M. M. Chiu (1). (1) Research chemists and chemist, respectively, Cereal Products Utilization Research Unit, USDA-ARS, Western Regional Research Center, Albany, CA 94710. Reference to a company or product by the USDA is only for purposes of information and does not imply approval of the product to the exclusion of others which may also be suitable. (2) Corresponding author. Phone: 510/559-5693. E-mail: <bek@pw.usda.gov> Cereal Chem. 74(5):599-604. Accepted May 5, 1997. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 1997.

Molecular characteristics were determined for mixed-linkage (1-3) (1-4)-beta-D-glucans (beta-glucans) extracted from Azhul, Crystal, Waxbar, and Prowashonupana barleys. beta-Glucans in extracts (with or without alpha-amylase, protease, hemicellulase, or xylanase treatment) were separated from other components by high-performance size-exclusion chromatography and detected with multiple-angle laser light scattering, refractive index, and fluorometry following postrefractive index treatment with Calcofluor. Pretreatment of barley with 70% ethanol (80°C, 4 hr) reduced beta-glucanase activity by ~20%. Hot-alcohol treatment also reduced beta-glucan extraction at 23 and 65°C by 42 and 14%, respectively. Molecular weights of beta-glucans in the first water extract were generally higher than in succeeding water and alkali extracts. Weight average molecular weights ranged from 0.44 × 10(^6) to 2.34 × 10(^6) g/mol after alpha-amylase treatment to remove interfering starch. Interference due to pentosans was not demonstrated using enzyme treatments.