Molecular Characterization of Barley β‐Glucans by Size‐Exclusion Chromatography with Multiple‐Angle Laser Light Scattering and Other Detectors

Abstract

Cereal Chem. 74(5):599-604Molecular characteristics were determined for mixed-linkage (1→3) (1→4)-β-D-glucans (β-glucans) extracted from Azhul, Crystal, Waxbar, and Prowashonupana barleys. β-Glucans in extracts (with or without αamylase, 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 β-glucanase activity by ~20%. Hot-alcohol treatment also reduced β-glucan extraction at 23 and 65°C by 42 and 14%, respectively. Molecular weights of β-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 α-amylase treatment to remove interfering starch. Interference due to pentosans was not demonstrated using enzyme treatments.

Barley β-glucans and arabinoxylans: Molecular structure, physicochemical properties, and uses in food products–a Review

“…Beer, Wood, and Weisz (1997) reported the mean peak M w of 1.6 Â 10 6 and 1.3 Â 10 6 for b-glucans extracted with hot water (90°C) from several US non waxy and waxy barley varieties, respectively. Knuckles, Yokoyama, and Chiu (1997) also observed inter-varietal differences in M w (0.57 Â 10 6 -2.7 Â 10 6 ) for water soluble b-glucans from barley. The elution patterns of b-glucan solutions from the size exclusion chromatography columns indicate a broad distribution of M w , and high ratios of the weight average MW to the number average MW confirm their inherent polydisperse nature.…”

Effect of Purified Oat β‐Glucan on Fermentation of Set‐Style Yogurt Mix*

“…Molecular weight distribution of β‐glucan was measured using size‐exclusion chromatography (SEC) with online postcolumn detection (Wood and others 1991; Knuckles and others 1997; Kim and others 2008). An SEC instrument (Shimadzu, VP series, Tokyo, Japan) equipped with an SEC column (Shodex, KS‐805) maintained at 25 °C was employed.…”

A theoretical framework for β-glucan degradation during barley malting

“…Although the estimates of the PD of the barley bglucans vary considerably between different studies (Jin et al 2004), careful assays of native, undegraded, b-glucans revealed a mol. wt of several hundred thousands to a few millions (Wood et al 1991;Beer et al 1997;Knuckles et al 1997;Irakli et al 2004), corresponding to a PD of 2-15 thousands units. Degradation of highly polymeric b-glucans by b-glucanase involves an initial phase during which the long chains are rapidly cleaved into a polydisperse population of fragments, but production of oligosaccharide end-products is negligible; whereas the subsequent decrease in the PD is slower (Gómez et al 1997;Carbonell et al 1998).…”